ON-AIR FAQ "Solar Studies and Sunny Interactions"

ASTRONOMY   AURORAS   BLACK HOLE    CME (CORONAL MASS EJECTIONS)    CONVECTION ZONE
CORONA   DISTANCE TO THE SUN   DOPPLER SHIFT    ELECTROMAGNET SPECTRUM   FLARES
GALAXIES   HELIOSEISMOLOGY    LIFE CYCLE OF THE STARS   MAGNETISM   NASA
NOAA AND SPACE WEATHER    ROCKETS   SATELLITE DRAG   SATELLITES   SIZE OF THE SUN   
SOLAR ENERGY   SOLAR MAXIMUM    SOLAR PHYSICIST   SOLAR RADIATION    SOLAR WIND
SPACE WEATHER   SPACECRAFT    STARS   SUN   SUNSPOTS    TELESCOPES (GROUND BASED)
TEMPERATURE OF THE SUN    YOHKOH SPACECRAFT

ASTRONOMY (CAREERS IN)

QUESTION:
How much education and experience do you need to get a job (not just an assistant) as an astronomer? Anthony, Grade 6 

ANSWER:
There are different employment opportunities within the astronomical field. You can be a computer programmer, telescope operator, instrument designer and builder and an electronics technician just to name a few. Most of these jobs require at least a bachelor's degree. So you'll be in college for at least four years. Traditionally, to become a scientist requires a Ph.D. This involves more advanced college course work and a special topic which you choose to study and later present. Graduate school can take another 5-6 years. You can get experience while working toward your bachelor's degree. Students are often hired to assist scientists with projects. Of course, the first time you will have no experience. The nice thing is that people are willing to help you get the experience you need. You just have to be willing to put forth the effort to learn. 

SCIENTIST: Detrick Branston, National Solar Observatory, Kitt Peak

AURORAS

QUESTION:
What gives auroras their different colors? 

ANSWER:
Aurora are different colors because the Earth's atmosphere has different elements in it. In particular, when a Nitrogen atom is excited, it gives us blue aurorae. Oxygen can give us red or green, depending on the amount of energy the atom is hit with. I hope this answers your question in sufficient detail.

SCIENTIST: Doug Biesecker, NASA Goddard Space Flight Center

QUESTION:
What can the colors of auroras tell us about them? Rachell, Willard Middle School, Berkeley CA 

ANSWER:
The color of aurorae tell us which elements are creating the beautiful colors. For example, when a nitrogen atom is excited in the atmosphere, it emits a blue light. Oxygen can give us either red or green light, depending on the amount of energy given to the oxygen atom. Other colors are sometimes created by combinations of these colors 

SCIENTIST: Doug Biesecker, NASA Goddard Space Flight Center

QUESTION:
How are auroras different colors at the same time? Darby, Lake Hazel Middle School, Idaho 

ANSWER:
Hi Darby! The different colors are caused by interactions with different atoms present in the Earth's atmosphere. Red and green are caused by interactions with oxygen and blue by nitrogen. If both oxygen and nitrogen are being bombarded by electrons at the same time, you will see all three colors. This means that you will often see pinks, purples and mauves as the colors all mix together in the atmosphere. If you are wondering how oxygen can cause both green and red--well, these are different energy states of oxygen. If it is excited to, what we call the first state, you will see green--if it is very excited then it will reach the second excited state and you will see red. Do you have a little brother or sister? If so, imagine the difference in their energy level if you gave them one bag of M&Ms and ten bags! They would certainly have much more energy with the 10 bags and would probably run around a lot more to get rid of their extra excitement. Green aurora are equivalent to 1 bag of M&Ms
and red aurora to 10 bags. Thanks for your question Nicky 

SCIENTIST: Nicky Fox, NASA Goddard Space Flight Center

QUESTION:
Can magnetism from auroras possibly help cure/relieve some of man's medical problems, i.e. migraines, epilepsy, & pain from arthritis type ailments? How do I find the research of the aurora's "medicinal" effect upon people living at the Poles? 

ANSWER:
The aurorae we see are related to the Earth's magnetic field (what we're seeing are energetic particles traveling along the earth's magnetic field lines), but aurorae are not in themselves magnetic. They are also confined to the upper atmosphere (higher than even a transcontinental airliner would travel) so people would never be able to "feel" the effects of the aurorae. I don't think any serious scientific research has been done on this question, but, hey, check out your favorite Internet browser. And if you do find out that aurorae help relieve migraines, let me know. (I actually suffer from migraines, you see...) Good luck! :) 

SCIENTIST: Meredith Wills, NASA Goddard Space Flight Center

BLACK HOLE


QUESTION:
Is there any possible way to calculate the size of a black hole? Jamie

ANSWER:
Yes. The size of a black hole depends only on how much mass it has. For example, a black hole with the mass of the Sun would have a diameter of 6 kilometers (3.6 miles)

SCIENTIST: Frank Hill, National Solar Observatory, Kitt Peak

QUESTION:
How does NASA detect black holes? Ryan 

ANSWER:
Black holes cannot be seen directly, but bright high-energy radiation in the ultraviolet and X-ray regions of the electromagnetic spectrum is emitted by charged particles undergoing violent acceleration in the neighborhood of the black hole and this can be detected with special telescopes above the Earth's atmosphere. 

SCIENTIST: Harrison Jones, NASA/GSFC, Laboratory for Astronomy and Solar Physics

QUESTION:
Is it true that in their search for black holes, scientists look for massive X-ray emissions? If so, why? What is the nature of a black hole? I was always taught that the matter contained in a black hole would be so dense as to create a gravitational pull strong enough that not even light could escape. Wouldn't that include X-ray "light"? What is the connection between X-radiation and black holes? Finally, if one were to point a camera at a black hole, what speculations exist as to what the resulting image would look like? Thanks; love the show.

ANSWER:
You are right that black holes are so massive that no light, including X-rays, can escape. This naturally makes black holes very hard to see. Our only hope to "see" a black hole is to look for its effects on the material near it. A black hole acts sort of like the drain in your kitchen sink--stuff near it is sucked into it, and the stuff swirls around as it goes in. It's this swirling material draining into the black hole that emits the X-rays, not the black hole itself. If we point a camera at a black hole, we think we would see the swirling material disappearing into a dark region.

SCIENTIST: Frank Hill, National Solar Observatory, Kitt Peak

QUESTION:
What is inside a black hole? Jon

ANSWER:
A black hole is a small volume which is the repository of enormous amounts of matter and energy. One can model the exterior neighborhood of a black hole, outside its event horizon, but the form of its contents is indeterminable.

SCIENTIST: Harrison Jones, NASA/GSFC, Laboratory for Astronomy and Solar Physics

QUESTION:
What is inside a black hole or what makes up the black hole? Brett, Cranbrook MS 

ANSWER:
A black hole is highly concentrated matter. They are thought to be created by the implosion of very large massive stars that suddenly collapse when they run out of fuel in their central core.

SCIENTIST: Frank Hill, National Solar Observatory, Kitt Peak

CME (CORONAL MASS EJECTION)

QUESTION:
About how often do CME's come off the Sun? Arlee and Nicole, Beers Street Middle School 

ANSWER:
During Solar Max, when the Sun is most active, CMEs can come out several times per day. Most of them are not headed towards the Earth, however. Eric Christian 

SCIENTIST: Eric Christian, NASA Goddard Space Flight Center

QUESTION:
How do you know when CME's occur? Chad and Chris, Beers Street Middle School 

ANSWER:
We can observe CME's only after they've started to occur. Although a group of scientists recently discovered that they can predict when certain CME's will occur. However, we cannot predict all CME's and even then it's less reliable than a 5-day weather forecast. When a CME is occurring, we can see them with special telescopes called coronagraphs, which block the bright light from the solar surface so that we can see the fainter atmosphere. 

SCIENTIST: Doug Biesecker, NASA Goddard Space Flight Center

QUESTION:
What is the frequency rate of CME's?

ANSWER:
That depends on where you are on the solar cycle. At solar minimum there is about 1 per day, and at solar maximum there are about 10 per day. At the moment there are about 3 to 4 CME's per day.

SCIENTIST: Jack Ireland, NASA Goddard Space Flight Center

QUESTION:
Could you tell us why the sun has Coronal Mass Ejections? Reba, Hydesville School Hydesville, California 

ANSWER:
That is a very very good question, and one that SOHO is trying to answer just now! What we think happens is that the magnetic field in the solar atmosphere gets twisted up in some way (we don't know how exactly) and when it reaches some kind of critical state (we don't know what that critical state looks like exactly) the magnetic field changes and a CME lifts off. As you can see there is a lot we don't know and that it's a question a lot of us are working on. 

SCIENTIST: Jack Ireland, NASA Goddard Space Flight Center

QUESTION:
CME's sound a lot like brain activity preceding and/or during a grand mal convulsion. Can you comment on this? Do you know what kind of medical comparison & research is being done (if any) using your current solar knowledge? 

ANSWER:
Hmmmm. I don't know very much about the current medical research into grand mal convulsions. What comparisons can be made between medical and solar research? Well, the only thing that springs to mind is tomography. CAT scans take a picture of the inside of the body, but only in thin slices, one at a time. The body is moved along, just a little bit to take another picture. From the series of pictures, a 3-D picture of the body is made using tomographic techniques. Solar physicists are just learning how to apply these techniques to images of the solar corona. In about 5 years, there will be a mission called STEREO, with 2 spacecraft designed to take images which we can use to make 3-D images of the Sun's corona.

SCIENTIST: Doug Biesecker, NASA Goddard Space Flight Center

CONVECTION ZONE

QUESTION:
Why does the convection zone at the equator spin faster then the poles? Morrie, Shawn and Mickey, Willard Middle School, Berkeley CA 

ANSWER:
Any ball spins faster at its equator than at its poles. Try it with a ball in your classroom. If you draw a line straight down the ball from pole-to-pole and spin the ball, everything makes one rotation. However, the equator of the ball must travel a greater distance around than the poles. So it must travel faster. Then there is differential rotation, which is an added effect. The differential rotation occurs because the Sun is not a rigid, solid body. It's a ball of gas. On the ball in your classroom, the line stays as a line no matter how much you spin the ball. On the Sun, if we could draw the same line on the Sun it would actually get dragged out into an arc, with the equator coming first and the areas closer to the pole coming later. 

SCIENTIST: Doug Biesecker, NASA Goddard Space Flight Center

CORONA

QUESTION:
Why is the corona of the Sun hotter than the surface? Garrett, Beers Street Middle School 


ANSWER:
That's a question scientists have been trying to answer for over 30 years. The photosphere (or surface) is at 6000 degrees, while the corona is at 1,000,000 (one million) degrees. There is enough energy in the Sun to heat the corona. However, the big problem is transferring the energy from the solar interior, or surface, up into the corona where it needs to be deposited. We don't know if the energy is moved and deposited by waves or by explosions or whatever. Those are the various methods which scientists have been examining.

SCIENTIST: Doug Biesecker, NASA Goddard Space Flight Center

QUESTION:
Why is it so hard to see the corona from Earth? Yared, Willard Middle School, Berkeley CA 

ANSWER:
Hello, Yared, Your question is a pretty good one! The corona is big and bright, so why shouldn't we see it? The problem is that the sky is so bright during the day that the corona gets washed out. It's there, but you can't see it well against the bright background. Did you know that the stars are up during the day, too? They're just washed out by the brightness of the sky. If you know exactly where to look, you can even spot Venus in the middle of a clear day. The only time that the Sun and corona are up in the sky, but the sky isn't bright, is during a solar eclipse. Then the corona is very clear and dramatic to see. Cheers, Craig 

SCIENTIST: Craig DeForest, NASA Goddard Space Flight Center

QUESTION:
Why is it so hard to see the Corona from Earth? Yared, Willard Middle School, Berkeley CA 

ANSWER:
The corona is so hard to see because it is 1 billion times fainter than the bright solar disk. It's hard to imagine 1 billion times isn't it? Well, it's like trying to see somebody behind the glare of car headlights. You know, like in the movies, the bad guys always get out of their car at night with the bright lights on so you can't see who they are. In order to see the corona, we block out the light from the bright disk (or surface) of the Sun. Then we can see the much fainter corona. Oh, so the physical reason the corona is so faint is that we only see the corona because it scatters the light from the photosphere. But it only scatters a little bit of the light, so it is faint. It only scatters a little bit of the light because the density of electrons and protons in the corona is a lot less than in the photosphere. 

SCIENTIST: Doug Biesecker, NASA Goddard Space Flight Center

DISTANCE TO THE SUN

QUESTION:
How do you measure the distance between Earth and stars? Brayton 

ANSWER:
Brayton, there are different methods used to measure the distance between Earth and stars. One method is called stellar parallax. Extend your arm in front of you and hold up a finger. Now alternately blink your eyes so that while one is closed the other is opened. What do you notice about your finger? Does it appear to shift its position back and forward against objects further away in the room? It is this apparent shift in the position of a star that astronomers measure to determine the distance to the star. Your finger represents the star, the background objects are background stars much farther away, your eyes represent positions of the Earth 6 months apart, and the bridge of your nose is the Sun. Observations are made of the star 6 months apart because that is the furthest distance that two points in the Earth's orbit can be separated. However, parallax only works for the nearest stars, those within about a hundred light years or so. For distant stars we depend on other techniques. For example, the further away a star is, the dimmer it is. That means that dimmer stars tend to be further. This is tricky, because small,
cool stars are also dimmer even if they are at the same distance. The nice thing about this is that cool stars are a different color, more reddish, so you can often tell whether a star is dim because it is small and cool instead of just far away. In the early 1900s, it was known that some stars pulsate. An astronomer named Henrietta Leavitt discovered that the brighter the star the slower it pulsated. This made it possible to determine the distances of galaxies millions of light years from Earth. Star clusters have helped us understand quite a lot of how stars vary in brightness, since they have different kinds of stars and all of the stars in any one cluster are about the same distance from Earth. There are a number of other methods for estimating the distances of stars. Binary stars are pairs of stars that orbit each other. The determination of their distance involves something called "spectroscopy," which uses a remarkable phenomenon called the Doppler effect. 

SCIENTIST: Detrick Branston, National Solar Observatory, Kitt Peak

DOPPLER SHIFT

QUESTION:
What is the difference between a red and blue shift? Joe, Darren and Dan, Beers Street Middle School

ANSWER:
The visible light spectrum spans a wavelength range from about 400 nanometers (1 nanometer = 1 billionth of a meter, abbreviated nm) to about 750 nm. The 450 nm light appears to your eyes as a deep blue color; the 750 nm light appears red. A "red shift" means that a spectral line (a narrow range of wavelengths of light) that is normally observed at say 500 nm is "shifted" towards the "redder" end of the spectrum to a longer wavelength of say 510 nm. Conversely, a "blue shift" means that the same spectral line is observed to be shifted towards the blue end of the spectrum, say at 490 nm. Red or blue shifts observed in spectral lines are typically caused by motion of the light source with respect to the observer. When the light source is moving away from the observer, it appears red-shifted; when the source is moving towards the observer it appears blue shifted. This change in the observed wavelength of a moving source is known as the "Doppler Effect" and it occurs for all kinds of waves, including light waves and sound waves too. For an example with sound waves, note that a car horn sounds different if the car is
approaching you or receding from you: the sound waves are doppler shifted by the car's motion relative to you. As it approaches you the horn sounds higher in pitch (shorter wavelength, analogous to blue shifted light) and as it recedes, the horn sounds lower in pitch (longer wavelength, analogous to red shifted light). So the short answer to your question is: a red shift implies the wave source is moving away from you and a blue shift implies the source is moving towards you. 

SCIENTIST: Tom Berger, Lockheed Martin Solar and Astrophysics Lab

QUESTION:
What is exactly heard coming towards the Earth or going away from the Earth with the doppler shift and how is it tracked? Ashley,
Belleview Middle School, Ms. Lin's 8th grade classroom 

ANSWER:
In astronomy, the doppler shift refers more often to light waves than sound waves. So what is actually measured is the wavelength of light coming to Earth from a distant star or galaxy. If the star or galaxy (or whatever it is that is being observed) is moving towards the Earth, the light will be "blue shifted", ie. it will appear to have a shorter wavelength (or "bluer color") than a non-moving source of the same light. Conversely if the star or galaxy is moving AWAY from Earth, it will appear "red shifted", or longer in wavelength (redder in color) than a non-moving source. Astronomers "track" the motion of distant objects in space by measuring the red or blue shifts of light from different objects. They use an instrument called a "spectrometer" to very carefully measure the wavelength of light from various objects and then compare that measurement to experiments with non-moving light sources in the lab to derive the relative shift of the light. 

SCIENTIST: Tom Berger, Lockheed Martin Solar and Astrophysics Lab

ELECTROMAGNETIC SPECTRUM

QUESTION:
How does the “Angstrom” measure light waves? Galen, Willard Middle School, Berkeley CA 

ANSWER:
Dear Galen, Thank you for your question. An "Angstrom" is a unit which we use as a measure of wavelength. It is named after a Swedish physicist (Anders Angstrom) who studied the Sun in the late 1800's. The wavelength of light is so small that we have to use different units of measurement. An Angstrom is a very small unit (one 100 millionth of a cm) which we need to use to measure the wavelengths of light. 

SCIENTIST: David Alexander, Lockheed Martin Solar and Astrophysics Lab

QUESTION:
Why do ultra violet rays of the Sun, sunburn people? From Mrs. Freeman's Astronomy Class, Meridian, Idaho 

ANSWER:
Hello Mrs. Freeman's Astronomy Class, How's the weather in Idaho? One of the biggest dangers of the Sun for us in our everyday lives is the problem of Sunburn. Much of the ultraviolet radiation from the Sun is stopped by the Earth's atmosphere but a significant amount makes it through and creates a nice market for the makers of sun block. The depletion of the ozone layer is making this problem a lot worse. What happens is that the UV radiation can penetrate the outer layers of the skin and be absorbed. This absorption of the UV is just like absorbing heat and can lead to burns. 

SCIENTIST: David Alexander, Lockheed Martin Solar and Astrophysics Lab

QUESTION:
What are hard and soft x-ray? What/why are they put out during a solar flare? What do they have to do with the Sun? Kay, Willard
Middle School, Berkeley CA 

ANSWER:
Good question, Kay. Hard and Soft are just two different ends of the spectrum of x-rays. Most of the images you're seeing of the corona are soft x-rays. (These would also be the x-rays that the doctor uses when he takes an x-ray of you.) Soft x-rays are emitted by things that have temperatures of between 500,000 and 6 million degrees. Hard x-rays are emitted by things that have temperatures of 6 million to 10 million degrees. You see x-rays emitted during solar flares because the plasma in the corona gets heated up. This happens a couple of different ways. Soft x-rays will be produced when the magnetic fields in the corona get tangled up and rearrange themselves. This produces a lot of energy. Hard x-rays will be produced by particles (say, electrons) that get sped up along magnetic fields and then get stopped all of a sudden. (In this case, they slam into the surface of the Sun, or the photosphere.) A good analogy would be like smashing your car at 60 mph into a brick wall, and thinking of the hard x-rays as the really loud crunching you hear. 

SCIENTIST: Meredith Wills, NASA Goddard Space Flight Center

FLARES

QUESTION:
About how many solar flares are emitted from the Sun in a day? Kay, Willard Middle School, Berkeley CA 

ANSWER:
Dear Kay, That's a very interesting question. As a matter of fact, flares aren't "emitted" from the Sun at all! They are large, hot explosions that happen on the surface. Sometimes when a flare goes off (and sometimes even when there isn't a flare), a thing called a "coronal mass ejection" or C.M.E., happens. A C.M.E. is a bunch of material that gets emitted from the Sun and shoots across the solar system. There is about one C.M.E. per day during the solar minimum activity period. We're just getting into a phase of maximum activity, when we expect several C.M.E.'s per day. Cheers, Craig 

SCIENTIST: Craig DeForest, NASA Goddard Space Flight Center

QUESTION:
What causes solar flares to occur? Carolyn, Willard Middle School, Berkeley CA 

ANSWER:
Dear Carolyn, You just asked one of the toughest questions we have in solar physics. To date we are not entirely sure what causes the eruption of a solar flare. We do know that it has a lot to do with the magnetic field of the Sun and how it develops in an active region. What can happen is that the magnetic field can get twisted as the surface of the Sun moves around and that a twisted field can build up energy (a bit like twisting an elastic band). Eventually, we think, that the amount of extra energy becomes too much for the field to hold on to and so it has to get rid of it. When it does this it does it very quickly and creates a lot of heat, lots of charged particles (electrons and protons) and very fast gas motions. Again, think of the elastic band. If you twist it too much it snaps with a loud noise and a lot of motion (watch your fingers if you try this). Thanks for your question. Maybe someday in the future you will be able to answer this one for yourself. 

SCIENTIST: David Alexander, Lockheed Martin Solar and Astrophysics Lab

QUESTION:
How long do solar flares last? Less then a second, or more? More then a minute or less? An hour? Kay, Willard Middle School,
Berkeley CA 

ANSWER:
Hey, Kay! I get to talk to you again. :) In fact, solar flares come in all shapes and sizes. The biggest ones will last for minutes to an hour or two. Those will probably be tens of times larger than the Earth. But we're finding that, as our telescopes get better, we can see smaller and smaller events. We call these smaller things microflares (which we've only been able to see for the past few years with SOHO) and even smaller than that are nanoflares (which we're not even entirely sure we've seen yet). I think I've seen some nanoflares with the TRACE satellite. Those are about the size of Nebraska and the shortest one I've seen lasted twelve *seconds*. This is really new stuff though. We only first observed them a few weeks ago. Cool, huh? :) 

SCIENTIST: Meredith Wills, NASA Goddard Space Flight Center

GALAXIES

QUESTION:
How many galaxies do we know about in the universe? Christian 

ANSWER:
We think there are several billion galaxies in the universe, but we have not seen them all. 

SCIENTIST: Frank Hill, National Solar Observatory, Kitt Peak

QUESTION:
What are the results of comparing and contrasting the behaviors of the microcosm (atoms and their components), to the behaviors of
galaxies? 

ANSWER:
Galaxies (like everything else in the universe) are composed of atoms, and there are some intriguing similarities between an atom with its electrons orbiting the nucleus, and the solar system with the planets orbiting the sun. However, the physical laws governing the atom are very different from the laws that govern the solar system and galaxies. For atoms, quantum mechanics governs the behavior, while for galaxies and planetary systems, gravity plays the major role. 

SCIENTIST: Frank Hill, National Solar Observatory, Kitt Peak

QUESTION:
How many known galaxies are there and how far away is the nearest one? Erica, Kelly and Lauren, Beers Street Middle School,
Hazlet, NJ 

ANSWER:
Our solar system is located in a spiral galaxy, which we see at night as the Milky Way. In this sense, the nearest galaxy is our own, since we are inside of it. Our galaxy is part of a group of about 20 galaxies known as the Local Group with two other spiral galaxies like our own and many smaller galaxies. The closest of the two spiral galaxies is Andromeda which is about 2 million light years away. Light travels at a finite velocity, the light from the Sun takes about 8 minutes to reach us. A light year is then the distance light travels in one year. The Large and the Small Magellanic Clouds, which are satellite galaxies of our own galaxy, are much closer; they are only about 150,000 and 200,000 light years away. There are millions of galaxies in the universe. When you look at a Deep Field image of the Hubble Space Telescope, you can see hundreds of galaxies in an area of the sky as small as President Roosevelt's eye on a dime held at arm's length. And in order to cover the whole sky with such a tiny image, you would need about 100,000 of these images. 

SCIENTIST: Rudi Komm, National Solar Observatory, Kitt Peak

HELIOSEISMOLOGY

QUESTION:
How did you discover the Sun makes sounds? Robert, Beers Street Middle School

ANSWER:
Scientists always expected the Sun to be a noisy place with sounds created by all the motions in the atmosphere, just like weather on Earth creates noise from winds and storms. We can't "hear" the sounds directly because of the vacuum between us and the Sun but we can measure how the gas is vibrating using the Doppler effect in absorption lines in the Sun's spectrum. The Doppler effect is also used by radar guns to measure velocities but for the Sun we usually use visible light rather than radio waves. In the 1960's Prof. Leighton and his students at CalTech first discovered the 5 minute acoustic noise. Before that, scientists knew about the sounds but not that there was a major "tone". It took a while, but scientists studying these noises finally realized in the 1970's that they could use sounds to study the inside of the Sun. The methods are similar to the way scientists can look inside the Earth using vibrations from earthquakes. But in the Sun, the vibrations are there all the time, we don't have to wait for "sun quakes". However, the math is more complicated and it takes careful measurements for months to get even a fuzzy picture of the Sun's insides. This work is called helioseismology which combines "helio" for the Sun and "seismology" which is the term used for the study of vibrations from earthquakes. 

SCIENTIST: Dick Shine, Lockheed Martin Solar and Astrophysics Lab

LIFE CYCLE OF THE STARS

QUESTION:
Will the Sun consume the Earth? Alex

ANSWER:
In around 5 billion years, the Sun will expand as it runs out of hydrogen as a fuel and switches over to helium. When this happens, the Sun will become so large that its surface will be beyond the Earth's orbit, and the planet will be consumed. 

SCIENTIST: Frank Hill, National Solar Observatory, Kitt Peak

QUESTION:
How hot is a big red giant? John, Jim and Dan, Beers Street Middle School, Hazlet, NJ

ANSWER:
The surface temperatures of red giants range from about 3,000-4,000 Kelvin (6000-8000 degrees Fahrenheit). 

SCIENTIST: Harrison Jones, NASA/GSFC, Laboratory for Astronomy and Solar Physics

QUESTION:
When the sun burns out, will we be able to replace it, or will we perish? Eric, Sean, Anthony and Dennis, Beers Street Middle School,
Hazlet, NJ 

ANSWER:
This is a difficult question to answer because it is hard to tell how advanced our technology will be when our Sun burns out. Our Sun should last for another billion years or so. We have evolved from single cells to the beings we are today in that amount of time. Who knows what we will be like in another billion years. I think that most likely thing to happen would be that we would have developed space travel that will allow us to travel to other stars and so when our Sun burns out, we won't be here anymore. One of the problems we might face is that our Sun will get much much bigger as it burns out. In fact, it will completely destroy Earth and most of the planets. As it dies, it will also get brighter and then dimmer. It might get so bright that it would boil away our atmosphere and Earth would become a dry planet like mars. Who knows? 

SCIENTIST: Rod Viereck, NOAA Space Environment Center

QUESTION:
How many cycles of stars are there? What are they Angela, Jackie,and Marcela, Beers Street Middle School, Hazlet, NJ 

ANSWER:
I'm not sure if this is what you are thinking of so please ask again if you need to--I can think of 3 basic types of cycles that stars go through--a life cycle, a pulsational cycle, and an activity cycle. The life cycle of stars, is roughly similar to the life cycle of plants and animals here on Earth. All stars are born, they grow up, get old, and die. There are basically 2 types of stellar life cycles--those that end with the star exploding into a supernova, and those that end with the star slowly expanding and then contracting. It's the mass of the star that determines what will happen. Some stars have a pulsational cycle--for instance they get brighter and dimmer over periods of time ranging from seconds to years. There are many different types of pulsating or vibrating stars and, in fact, the Sun is one of them. The Sun pulsates with about 10 million different tones of sound, much like a huge musical instrument. The last basic type of stellar cycle is an activity cycle. The Sun is the best known example, the number of sunspots and flares goes up and down with a period of around 11 years. We know of several other stars that have activity cycles as well. 

SCIENTIST: Frank Hill, National Solar Observatory, Kitt Peak

MAGNETISM

QUESTION:
Dear Live From the Sun, If sunspots have a strong magnetic field, then how come the Sun doesn't have an atmosphere? Chris,
Charleston Middle School, Charleston, IL 

ANSWER:
The Sun is made of gas, so it does have an atmosphere, but it is not one that we could breathe in. To hold on to an atmosphere, you need gravity, not magnetic field. Small moons cannot have atmospheres because their gravity is so low that any gases near them would quickly escape into space. 

SCIENTIST: Louis Strous, Lockheed Martin Solar and Astrophysics Lab

QUESTION:
What is magnetism and is it necessary to have magnetism in order to travel with a spacecraft in space? Nastasha, Mike B, and Christie,
Beers Street Middle School, Hazlet, NJ 

ANSWER:
Magnetism just means that a magnetic field is present, either from a permanent magnet (iron) or from electric currents. Electro-magnetism is one of the four basic forces of the universe. The magnetic fields of the Sun and the Earth are caused by moving electrically conductive material inside the Sun and Earth (plasma for the Sun and molten iron for the Earth). You don't need magnetism to travel in space. Eric Christian 

SCIENTIST: Eric Christian, NASA Goddard Space Flight Cente

QUESTION:
Is there any place in our solar system that an object would not be in some type of magnetic field? If you were doing a controlled experiment to find out the effect of a magnetic field on some organisms, what could you do to create no magnetic field for the living things to be in?
Josh, Grade 8, Deer Park Middle Magnet 

ANSWER:
Well, there is no natural occurring place in our solar system where there is no magnetic field. The whole solar system is filled with the magnetic field of the Sun, except around the planets where the planetary magnetic fields dominate. Outside the solar system, which is interstellar space, there is yet another magnetic field. But, we can still do that experiment you wanted to do. Have you ever heard of superconductors? Superconductors are super for lots of reasons. One is that as a super conductor, it can stop magnetic fields. So, if you constructed a hollow sphere or box out of superconducting material, you could make it so that there is no magnetic field inside. So, you could put the living organism inside of a superconducting box. 

SCIENTIST: Doug Biesecker, NASA Goddard Space Flight Center

QUESTION:
Is anyone studying the effects the Sun's magnetism has on humans, such ad moods and health? Thank you Coyote 

ANSWER:
Well, the effects of the length of day have been studied. However, I don't know that there have been any studies of the effect of the Sun's magnetism. It may be that the Sun's magnetic field never makes it to where we are on Earth. The Earth's magnetic field keeps the Sun's field out. Of course, the Sun's field does have an effect on the Earth's field. How important is it? I'm not sure. But we have to also consider the magnetic fields generated by things like power lines. I know that there is a lot of research going on about the effects of high power lines on the people who live near them. That research might tell you something about the effects the Sun's magnetic field might have. Thank you. 

SCIENTIST: Doug Biesecker, NASA Goddard Space Flight Center

NASA

QUESTION:
What is NASA going to do next? What are some of the major projects? Matt, Cranbrook MS 

ANSWER:
Well, NASA is going to do all sorts of things. I'll tell you what I know. But one web site that will tell you a lot is http://spacescience.nasa.gov/ Up next in solar physics are missions called SOLAR-B, STEREO, and SOLAR PROBE. Solar-B will be in conjunction with the Japanese Space Agency and will study the Sun in even finer detail than SOHO. STEREO will consist of two spacecraft, both taking pictures at the same time which will allow us to make 3-dimensional pictures of the Sun. Solar probe will actually fly within 4 solar radii (or 3 million kilometers) of the solar surface. The Hubble Space Telescope is due to be repaired later this year during a shuttle mission. There is a major X-ray Observatory called XMM scheduled to be launched soon as well. And of course, NASA sends at least one mission to Mars every 2
years. 

SCIENTIST: Doug Biesecker, NASA Goddard Space Flight Center

QUESTION:
What is the current plan to inhabit Mars? When will people live there? Philipp, Cranbrook MS 

ANSWER:
There is no current mission planned to take people to Mars. While there are studies to look at doing this in the future, right now there is neither the money, nor the national enthusiasm necessary to do this. So it will almost certainly be 20-40 years in the future before any manned mission heads to Mars, and longer still until we actually start living there. Eric Christian 

SCIENTIST: Eric Christian, NASA Goddard Space Flight Center

NOAA AND SPACE WEATHER

QUESTION:
What does NOAA stand for and what do you have to do with space weather? James and Thomas, Beers Street Middle School,
Hazlet, NJ 

ANSWER:
NOAA stands for National Oceanic and Atmospheric Administration. NOAA is part of the Department of Commerce and we do lots of things related to weather of all kinds. If you ever watch the Weather Channel you will see data that NOAA collects. Actually, the group that I work with is called the Space Environment Center (SEC) and they have been around longer than NOAA itself. I believe that SEC started when the radio communications people discovered that radio waves reflected off the ionosphere were disturbed when the ionosphere was disturbed and these disturbances were caused by solar activity. So almost 10 years before NOAA was formed, there was a group of people here in Boulder studying space weather and trying to predict it. If you consider the atmosphere to be the envelope of gas around Earth, then the atmosphere reaches up into space. Satellites feel the drag of the atmosphere. The upper atmosphere gets ionized by the Sun to create the ionosphere which is one of the major components of space weather. Therefore, space weather is simply an extension of the weather on Earth. 

SCIENTIST: Rod Viereck, NOAA Space Environment Center

ROCKETS

QUESTION:
What is the name of the biggest rocket and how big is it? Frank and Joe, Beers Street Middle School, Hazlet, NJ 

ANSWER:
The biggest rocket ever *designed* was the Sea Dragon, and it would have weighed 20,000 tons! However, the project did not reach completion. The largest rockets we have serve as vehicles which are used to launch projects to space. The Saturn V, which was used to get Apollo to the moon, was enormous too--3000 tons. I am not sure if that was the absolute biggest rocket, but it's the biggest one I've seen! 

SCIENTIST: Barbara Thompson, NASA Goddard Space Flight Center

SATELLITE DRAG

QUESTION:
What is a satellite drag? Beers Street Middle School, Hazlet, NJ 

ANSWER:
What is a satellite drag? This term refers to the resistance, or drag, on the satellite of the atmosphere it is flying through. The atmospheric density changes with height above the Earth's surface, and with time, just as our 'weather' at the surface has highs and lows. We humans can't feel this, but imagine running along a beach, first through the air, and then through the water. We can certainly feel the difference in resistance of the water in comparison to the air on our legs. The water is denser: many more molecules in a given volume. So if the atmosphere through which the spacecraft is flying becomes more dense, it slows down. This resistance is called satellite drag. 

SCIENTIST: Zdneka Smith, NOAA Space Environment Center

SATELLITES

QUESTION:
What is the closest the satellite gets to the Sun in it's orbit and how do you control and fix it without someone there to do the work?
Aaryn, Grade 6, Deer Park Middle Magnet 

ANSWER:
Well, NASA is planning a probe to get as close as 4 solar radii of the Sun, that's 3 million kilometers. How will they fix it? They can't fix anything which breaks unless it can be fixed by remote control. It will probably be controlled by a program which runs automatically. 

SCIENTIST: Doug Biesecker, NASA Goddard Space Flight Center

QUESTION:
What material do you use on a satellite like SOHO that allows remote sensing and is strong enough to protect the instruments inside from the melting SUN? Chad, Grade 6, Deer Park Middle Magnet 

ANSWER:
Hi, Chad, You might think that the Sun is pretty hot where SOHO is -- but it's not much hotter than here on Earth! SOHO is only 1% of the way to the Sun from where we are, so the sunlight is about 2% hotter. That's not much hotter than right here. So it's not a big deal to shield the instruments from being *melted*. But we do have to use the same sorts of special filters to protect the cameras that you would have to use here on Earth. (You wouldn't want to aim your camera straight at the Sun, because the lens concentrates the light and could burn the film!) One kind of solar filter is a piece of glass with a very very thin layer (less than 1/100 the thickness of a human hair) of silver or aluminum on it. The metal reflects most of the light of the Sun but lets a little bit through so that the camera can work. 

SCIENTIST: Craig DeForest, NASA Goddard Space Flight Center

QUESTION:
Can a robot be created to withstand the heat of the sun? Nicole, Shyam, and Chris, Beers Street Middle School, Hazlet, NJ

ANSWER:
There is a spacecraft called Solar Probe that is being designed to get close to the Sun, about 4 times the radius of the Sun. But there is no known material that can actually get down to the surface of the Sun without melting. Even Solar Probe has what's called an "ablative" shield, a material that will start to melt, but won't melt through in the short time that the spacecraft is close to the Sun. Solar Probe is due to launch in 2008 or so. Eric Christian 

SCIENTIST: Eric Christian, NASA Goddard Space Flight Center

QUESTION:
How can you tell which bit of data is coming from which satellite? Don't they all get mixed up in outer space with so many satellites and things sending back data to our Earth? CAMS2, Grade 6, Deer Park Middle Magnet 

ANSWER:
Excellent question! We know because data is sent back in packets which have unique identifiers. What does that mean? Well, the bytes (information) are sent back a little bit at a time. At the front of every packet, there are identifying numbers which are used to sort the packets out. Not only which spacecraft they belong to, but which instrument on the spacecraft, or even the correct order of the packets. 

SCIENTIST: Doug Biesecker, NASA Goddard Space Flight Center

QUESTION:
Is all the information you receive happening the moment you receive it? Lindy Humber, Ms. Hammond's fifth grade class 

ANSWER:
Hi Lindy There are different delays on the different datasets. For example, the images I was showing on the TV show were coming in live with just a few minutes delay, however, we only get about 6 hours of data per day in real time. The POLAR spacecraft has large tape recorders on board which will record all of the data from each of the different instruments on the spacecraft. During the real-time passes, all of this data is played back to a ground receiver and sent to us here at Goddard Space Flight Center. The images of the aurora are displayed in real-time on the web during these passes, but during the time we are not in contact with the spacecraft, they are also recorded and played back later. The data from the other instruments are never available in real-time as the data is much more complex and require more rigorous processing before they can be analyzed. The longest we have to wait for data from the POLAR spacecraft is usually one day, unless there are unforeseen problems. Thanks for your question Nicky 

SCIENTIST: Nicky Fox, NASA Goddard Space Flight Center

QUESTION:
How much testing do you have to do before you know that the instruments you will be sending up in a satellite will really send back the
information you want? Nina, Grade 6, Deer Park Middle Magnet 

ANSWER:
This is really a tricky thing. First you have to calibrate the instrument so that you are sure that when it measures something, you are truly getting the number you think you should. Suppose you want to measure the x-rays that come from a distant star and you want to know precisely how many x-rays that star produces. Before you launch your instrument, you would take it to a calibration facility that can produce x-rays. Then you check to see if your instrument measures the correct number of x-ray photons. Then you want to make sure that your instrument will survive the harsh environment of space and of the launch itself. This is often called “shake and bake” because you literally have to shake it on a shake table and then bake it in a special oven. I have seen instruments fly apart when the shake them on a shake table. Since many instruments can not run in air, they have to be in a vacuum while they are cold and hot. This requires very special testing environments call “Thermal Vacuums” because you can change the temperature while it is in a vacuum. Unfortunately, this is all very hard on instruments, especially ones with sensitive optics and moving parts. So there is a fine line between testing it just enough to make sure it will survive and testing it too much and actually
breaking it. 

SCIENTIST: Rod Viereck, NOAA Space Environment Center

QUESTION:
What was the first transmission from earth that could be received by another planet? Alex, Cranbrook MS 

ANSWER:
Dear Alex, It is not clear what the very first transmission detectable from the Earth would be. What is certain is that nothing before the advent of radio communications at long wavelengths (>10m or so) would escape Earth's atmosphere. This puts a time limit on when the first transmission could occur. The general consensus is that radio waves from Earth now reach out to about 50 light years making early TV shows like "I Love Lucy" a good candidate. I believe in the movie "Contact" it was claimed that radio signals from Nazi Germany were the first to use long enough wavelengths to escape into space. I am not sure how true this is but it would be roughly in the correct time frame. 

SCIENTIST: David Alexander, Lockheed Martin Solar and Astrophysics Lab

SIZE OF THE SUN


QUESTION:
How many Jupiters could fit in the Sun?

ANSWER:
The diameter of Jupiter is 142,800 km. The diameter of the Sun is 1,200,000 km. all you need is the formula for the size of a sphere and you can do the math! 

SCIENTIST: Jack Ireland, NASA Goddard Space Flight Center

QUESTION:
How big is the Sun and do you think that our Earth will become a Big Red Giant in the near future? Mike and Wendy, Beers Street
Middle School, Hazlet, NJ 

ANSWER:
Mike and Wendy, The Sun is pretty big--it's a little over 100 times as big around as the Earth is! But its *volume* is more than a million
times bigger than Earth's! The Sun will indeed get larger over the course of its lifetime. Eventually (about a billion years from now), it will start to
grow and, we think, will eventually engulf the Earth. But that's a *long* time in the future--human beings have only been around for something like
1/1000th of that much time. 

SCIENTIST: Craig DeForest, NASA Goddard Space Flight Center

SOLAR ENERGY


QUESTION:
How many typical houses could be heated by the energy released by the Sun each second? Maximilian 

ANSWER:
The energy that falls onto the surface of the entire Earth is roughly enough to heat a trillion typical houses, meaning houses with an area of about 3,000 square feet. A trillion is a million times a million. This is roughly how many houses it would take to cover the entire surface of the Earth, which, on the average has a fairly comfortable temperature, thanks to our Sun. 

SCIENTIST: Charlie Lindsey, National Solar Observatory, Kitt Peak

SOLAR MAXIMUM


QUESTION:
How do you know the next solar maximum will occur around 2003? Morrie, Shawn, and Mickey, Willard Middle School, Berkeley
CA 

ANSWER:
We know because the Sun is very regular. People have been counting the number of sunspots since about 1740, and we can see that the
sunspots and the solar activity reach a maximum every 11 years. The last solar max was in about 1991/1992 so the next one is due in 2002/2003.
Eric Christian 

SCIENTIST: Eric Christian, NASA Goddard Space Flight Center

SOLAR PHYSICIST


QUESTION:
What does a solar physicist do? Chris and Alan, Beers Street Middle School, Hazlet, NJ 

ANSWER:
The short answer is that solar physicists study the physics of the sun and/or teach the subject to students. But there are many different ways that this is done. Some use computer programs and math to try to understand how the Sun makes all the interesting things we see and to predict what will happen in the future. Predicting flares and other types of solar storms is especially interesting because these can affect satellites and people in space. Others observe the Sun using telescopes on the Earth or satellites. Often this means spending a lot of time designing and building the instruments and spacecraft before being able to use them. We are always trying to get better/sharper pictures and more accurate measurements. Building state-of-the-art instruments and satellites and using them can be very rewarding and exciting, sometimes too exciting when something goes wrong or you find that the money has run out. But the best parts are seeing something that no one has ever seen before and perhaps making an important discovery. Most solar physicists are motivated by curiosity about what is happening on and in the Sun although understanding the Sun, especially the "storms", has practical applications, Solar physicists also seem to spend a lot of time traveling. Besides trips for observing which can take us to mountain tops, the south pole, or even the Space Shuttle (at least two solar physicists, Dr. Acton and Dr. Bartoe, have flown), we also have meetings with our colleagues around the world to share our results. Sometimes in our country and sometimes in
theirs. After a while it seems that you get to visit a lot of interesting places. 

SCIENTIST: Dick Shine, Lockheed Martin Solar and Astrophysics Lab

SOLAR RADIATION


QUESTION:
Can you contain solar radiation in any container? Anthony, Beers Street Middle School, Hazlet, NJ 

ANSWER:
Well not really. Solar radiation is essentially light and light doesn't like to stand still. It is always moving at the speed of light. So if you were to collect it in a bottle, it would hit the walls of the bottle and be absorbed. Even if you could make a bottle out of mirrors, the mirrors absorb a little bit and thus, the radiation would get absorbed. Since light bends in a gravitational field, I suppose you could have a very strong field and light could just go around and around like planets around the Sun. In fact, black holes have such a strong gravitational field that light can not get out. In a way, they are collectors of radiation. Black holes would be a little dangerous to carry around though… and they are much much too heavy to hold. 

SCIENTIST: Rod Viereck, NOAA Space Environment Center

QUESTION:
Earth's atmosphere and the Van Allen belt protects us from solar radiation. It is said that the average human receives about .17 rem per
year on the surface of the Earth. How many rem per year would someone receive outside of the Earth's atmosphere? How many rem per year
would someone receive outside the Van Allen belt? 

ANSWER:
The average dose per year received at sea-level is about 100 mrem (0.1 rem) coming about equally from galactic cosmic ray exposure (which is always present), the body itself (primarily Potassium 40) and from medical exposure. 2) Our partial protection from cosmic ray exposure derives from the atmosphere, and from the Earth’s magnetic field. The van Allen belts are an inclusion in the geomagnetic field and do not constitute part of that protection.. 3) At SST (55,000 - 60,000 ft) altitudes the dose rate increases to about 1 - 2 mrem/hr.with another order of magnitude to the top of the atmosphere. (Actually this value would depend on the latitude of observation because of the effect of Earth’s magnetic field.). A further consideration is that of Solar Cosmic ray event whereupon the Sun occasionally emits a burst of energetic articles which may, on occasion, increase the radiation levels substantially. The largest event of the past 20 years was observed to increase the radiation level at SST altitude to 10-15 mr/hr a factor of 10 or so above its normal background levels, but only for a few hours. Such events are quite rare. 

SCIENTIST: Rod Viereck, NOAA Space Environment Center

QUESTION:
Is there any chemical that can protect us from solar radiation on our skin?
Chris and Mike, Beers Street Middle School, Hazlet, NJ 

ANSWER:
First of all, do you have one in mind? Like the ozone layer in our atmosphere? Or skin creams that we can buy to protect ourselves from sunburn on the beach, on snow, ice etc.? Our pharmaceutical companies are getting pretty good at Sun creams: it's hard to beat zinc oxide, which is cheap, though usually white. I think you mean our atmosphere. The atmosphere in general is great for protecting us from the full impact of the Sun's radiation, which is why we at the Earth's surface do not need much protection. Of course you can look at it the other way; life on Earth as we know it evolved to live happily on the surface of the Earth. Only when we (people) go up in spacecraft, do we need space suits. The ozone layer in the atmosphere is the important layer because it absorbs the ultra violet radiation that causes rapid sunburn. 

SCIENTIST: Zdneka Smith, NOAA Space Environment Center

SOLAR WIND


QUESTION:
Is there wind in space? If so, how fast can it blow? 

ANSWER:
Indeed, there is wind in space and it can blow very fast. The sun is like a big explosion going all the time. All of this energy accelerates particles and they race away from the Sun. This is called the “Solar Wind”. The solar wind is fast… very fast. It usually blows hundreds of kilometers per second. How fast is that? Well 1 kilometer is about 0.6214 miles 1 second is 1/(60 x 60) hours or 0.000278 hours so 1 km/sec x 0.621 miles/km / 0.000278 hours/sec = 2,236 miles per hour Now the solar wind travels at hundreds of km/sec and can actually reach speeds of more than 1000 km/sec which would be more than 2,236,000 miles per hour! Watch Out! How long would it take to reach Earth? Fortunately for us, the wind is not very dense. In fact, there are so few particles that the wind hardly pushes on spacecraft that are out in space. On Earth there are 2.5 x 1019 particles of air per cubic centimeter. That is 2.5 with 19 zeros after it. In the solar wind there are typically 10 or maybe 100 particles per cubic centimeter. So even though the wind is fast, it is not very strong. And on Earth the air is made of mostly nitrogen and oxygen molecules while the solar wind is made of electrons and protons. One oxygen molecule is about the same weight as 32 protons so in addition to having fewer particles in the solar wind, the particles themselves are much lighter. It is strong enough to push spacecraft around a little bit. In fact, there are proposals to use the solar wind to actually sail a spacecraft. In order to have enough force on a spacecraft though, they would make a
sail that would be gigantic. Every big sail boat has a sail that is about 5 by 10 meters or about 50 square meters. The solar sails would be as much
as 1000 by 1000 meters or 1,000,000 (one mill) 
 
SCIENTIST: Rod Viereck, NOAA Space Environment Center

SPACE WEATHER


QUESTION:
What is the difference between Earth and space weather and what is the greatest contributing force that creates space weather? James
and Tom, Beers Street Middle School, Hazlet, NJ 

ANSWER:
We can easily see and feel much of Earth weather. The temperature gets warmer and colder. clouds form and we may get rain or hail. Thunder and lightning can be very threatening if we are outside without proper shelter and protection. We are used to the local seasons. We rarely notice space weather directly with our senses. Most of its effects are high above the Earth, from a hundred kilometers or so all the way to the Sun and out past the edges of the solar system. I can only think of two common parts of space weather that are sensed directly by people. During a total eclipse of the Sun, we can see the visible corona, part of the solar weather. If we live far enough north or far enough south, we can see aurora (northern or southern lights) which is interaction between particles from solar weather and the Earth's upper atmosphere. Just as all of the energy we use on Earth comes from the Sun, the Sun is the greatest contributing force creating space weather. Some of the material high above the Sun flows into space. It is sort of like boiling off the Sun. This creates the solar wind. Like the winds on Earth, the solar wind has different speeds and at different places. Unlike the winds on Earth, magnetic fields strongly control the solar wind. The magnetic field of the solar wind
interacts with the magnetic field of the Earth in complicated, interesting ways. Thanks for your interesting question. Lorne Matheson 

SCIENTIST: Lorne Matheson, NOAA Space Environment Center

QUESTION:
Can you name any spectacular space weather? Mike, John, Crystal and Mellisa, Beers Street Middle School, Hazlet, NJ 

ANSWER:
A very spectacular event is a total eclipse of the Sun. During the eclipse, you can see the corona, which is material leaving the Sun, controlled by the Sun's magnetic fields. This material and magnetic fields are the source of space weather. Another spectacular event is aurora, northern or southern lights, which are the interaction of space weather and the upper atmosphere of the Earth. The aurora is also influenced by the Earth's magnetic field. A spectacular event that couldn't be seen, but had large effects was an electrical power interruption in March of 1989 in eastern Canada. A large area was without electrical power due to rapid changes in the Earth's magnetic field caused by space weather. It often takes hours to get the power generators working again and the electrical power grid reconnected. Miles and miles of no street lights, no traffic lights, no electricity to run the fans for heating our homes, no lights in our homes except for flashlights and candles. Just as snow or ice storms can damage the power lines in our cities, some types of space weather can damage satellites in space. Not all satellite failures are due to space weather. Satellite failure can lead to loss of paging services, loss of good weather predictions, or loss of some television services. This is another
case where we cannot directly see the space weather, only measure some of the changes and watch the effects. Thanks for the good question.
Lorne Matheson 

SCIENTIST: Lorne Matheson, NOAA Space Environment Center

SPACECRAFT


QUESTION:
How many spacecraft has NASA launched? Suzi, Ms.Hammond's class 

ANSWER:
I'm not sure of the exact number, but it's in the thousands. Weather satellites, communication satellites, moon probes, planetary probes, space physics mission, the manned missions--it adds up quickly! 

SCIENTIST: Craig DeForest, NASA Goddard Space Flight Center

STARS


QUESTION:
What is the largest known star? CG McClure 

ANSWER:
Hi, the largest stars are about 100 times the solar mass. The current record holders are seven main-sequence stars located in the R136 cluster at the heart of 30 Doradus Nebula in the Large Magellanic Cloud. These stars have about 155 times the mass of our Sun. 

SCIENTIST: Rudi Komm, National Solar Observatory, Kitt Peak

QUESTION:
Do the stars give off any light in the daytime? 

ANSWER:
Yes, the stars shine during the daytime. But, our Sun is so much brighter that we cannot see them. 

SCIENTIST: Rudi Komm, National Solar Observatory, Kitt Peak

QUESTION:
Do you know how many stars fall each year? Laura and Sukhdeep, Beers Street Middle School, Hazlet, NJ

ANSWER:
Stars do not fall. If you are asking about "shooting stars" or meteors, which are actually small rocks and dust that continually enter the Earth's atmosphere, I think that several million hit the Earth's atmosphere every year. Of these, a few hundred are large enough to survive the fiery trip down to Earth's surface. These are called meteorites. 

SCIENTIST: Frank Hill, National Solar Observatory, Kitt Peak

QUESTION:
How long do stars remain bright? Shannon, Kristy and Jillian, Beers Street Middle School, Hazlet, NJ 

ANSWER:
Dear Shannon, Kristy, and Jillian, Thank you for your very interesting question. How long stars remain bright depends a great deal on
HOW bright they are. The brightest stars burn up their fuel fast, and don't last nearly as long as the dimmer ones. Some start out hundreds of
thousands of times as bright as our Sun. They don't last very long at all, probably not even a million years. What? A million years seems like a long
time? Of course it is for us, but for stars its very short. Our Sun has been around for about 5 BILLION years, and we think that it will continue to
shine about the way it is now for another 4 or 5 billion more years. That is thousands of times longer than the brightest stars that are known. Sad
to say, not even the Sun is expected to last forever. However, 4 billion years is definitely a long time for us, so try not to worry about the Sun
going out at least for a while. 

SCIENTIST: Charlie Lindsey, National Solar Observatory, Kitt Peak

QUESTION:
Why are all stars the same shape? Jamie, Jenna, Steven and Kenny, Beers Street Middle School, Hazlet, NJ 

ANSWER:
Stars and other large gravitationally bound bodies tend to be spherical because gravity is isotropic (the same in all directions). A central
condensation of matter will attract another object with a force acting along the line joining the two objects which depends only on the distance and
the masses of the two objects, not their orientation. It is not quite true that all stars are the same shape. Very rapidly rotating stars are slightly
oblate and close binary stars are distorted by the tidal forces exerted by their companions, sometimes enough that material flows from one star to
another.

SCIENTIST: Harrison Jones, NASA/GSFC, Laboratory for Astronomy and Solar Physics

SUN


QUESTION:
Why is the Sun called Sun instead of Helios. Josh, Lake Hazel Middle School, Idaho 

ANSWER:
There are many names for the Sun in many languages and cultures. Helios is the Greek word, Sol is the old Latin word that the ancient
Romans used, and Sun comes from Middle English, Anglo-Saxon, and German. Since our culture originated in England, we use the word "Sun" 

SCIENTIST: Frank Hill, National Solar Observatory, Kitt Peak

QUESTION:
What cultures worshiped the Sun as a god?

ANSWER:
I am not an expert on ancient cultures, but I know that both the Egyptians and the Mayans did. Many other cultures have as well. Eric
Christian 

SCIENTIST: Eric Christian, NASA Goddard Space Flight Center

QUESTION:
How does the Sun make heavier elements like carbon and iron? 

ANSWER:
The source of the Sun's power is the burning of hydrogen in its core. Hydrogen, the lightest element, is fused into helium and heavier elements, and in the process a lot of energy is liberated. Carbon and Iron are formed as the lighter elements undergo further burning. 

SCIENTIST: Barbara Thompson, NASA Goddard Space Flight Center

QUESTION:
Is all the information you receive happening the moment you receive it? Lindy Humber, Ms. Hammond's fifth grade class 

ANSWER:
Not everything is happening "real-time". On the ACE spacecraft, a lot of the data is stored onboard for a day and then sent down at a
high rate over a few hours. Then it's usually a day or more before most of us scientists actually look at it. Eric Christian 

SCIENTIST: Eric Christian, NASA Goddard Space Flight Center

SUNSPOTS


QUESTION:
What causes sunspots? Sarah and Danielle, Beers Street Middle School 

ANSWER:
Sunspots are caused by strong magnetic fields in the Sun's photosphere (the visible "surface" of the Sun). They look dark because they are cooler than the rest of the Sun (but they are still hot enough to vaporize anything.) The reason they are cooler is because the strong magnetic field partially blocks the heat rising from below. Large sunspots are usually cooler and darker than small ones. Exactly why the magnetic field concentrates to form sunspots is not well understood. 

SCIENTIST: Dick Shine, Lockheed Martin Solar and Astrophysics Lab

QUESTION:
How did Galileo discover sunspots? 

ANSWER:
Galileo saw sunspots by looking at the Sun through the telescope he had just invented. Luckily for him, his telescope was so primitive, he did not blind himself! You should NEVER look at the Sun through a telescope without special filters to protect your eyes! Galileo was not the first person on Earth to see sunspots. There are records of sunspots observed through heavy clouds in China in the 13th century. There is no record of how blind the observers were after this... 

SCIENTIST: Frank Hill, National Solar Observatory, Kitt Peak

QUESTION:
About how many sunspots do you usually see on the Sun? How will this change during Solar Maximum? Kara and Nicole, Beers
Street Middle School 

ANSWER:
Over the course of the 11 year sunspot cycle, the number of sunspots seen on any given day varies from zero (during solar minimum) to over 200 during solar maximum. Of course of those 200 or so sunspots, not all are large round sunspots with penumbra--many are much smaller (only 5-10,000 km in diameter) and do not have penumbral structure. Some scientists refer to these smaller spots as "pores". Right now we are nearing solar maximum and the number of spots visible on any given day is increasing. Today (13-April) there are 6 "active regions" on the Sun's earth-facing hemisphere, each with many sunspots of various sizes. You can view a picture of today's Sun in visible light from the SOHO satellite at http://sohodb.nascom.nasa.gov/cgi-bin/summary_image/990413. Click on the MDI Intensitygram link to see the sunspots.  

SCIENTIST: Tom Berger, Lockheed Martin Solar and Astrophysics Lab

QUESTION:
Are scientists close to discovering how Sunspots happen? Ben, Willard Middle School, Berkeley CA 

ANSWER:
The question of how sunspots happen is similar in some ways to the question of how leopard spots happen. The answer depends on how much detail you want. How do leopard spots happen? This has to do not just with the leopards themselves, but also a lot with their environment. If their prey were blind, or very slow, then leopards did not have to have any camouflage spots. If they lived in the polar regions, then they'd stand out like a sore thumb against the white ice and snow unless they had a white coat and no spots. But then you can ask: why are their prey not slow or blind, and why do leopards live in grasslands and not in the polar regions? And so on: Every answer leads to more questions. To understand leopards, you cannot look at just them, but you have to look at how leopards and their surroundings influence each other. It is the same for sunspots. To understand sunspots, you have to understand their surroundings, too; you have to understand the whole Sun. Solar physicists have discovered very many things about the Sun, and also about sunspots: we know that sunspots look dark because they are cooler than their
surroundings and also very big; we know that sunspots are areas where the magnetic field of the Sun is very concentrated; we know that this magnetic field comes up from deep inside the Sun because the magnetic field helps make the gas that's in it buoyant like a balloon; and we know many more things about them, too; too many to list them all, and each one leads to more questions: Why are sunspots cooler than their surroundings? Why do they get to be as big as they do, and not always smaller or sometimes even bigger? Where does the magnetic field deep inside the Sun come from? Why is the solar cycle 11 years and not 3 or 35? Every time we "discover" the answer to one of the questions about how sunspots happen, more questions pop up. The finish line keeps moving away from us. So, the answer to your question is: Scientists are "sort of" close to discovering how sunspots happen. Scientists have discovered a lot already about how sunspots happen, but they also discovered that there is much more yet to learn. 

SCIENTIST: Louis Strous, Lockheed Martin Solar and Astrophysics Lab

QUESTION:
Are all sunspots the same color? Does the temperature of the sunspots affect what color they are? Charde King, Willard Middle
School, Berkeley CA 

ANSWER:
Hi Charde! Sunspots, dark areas on the solar surface, are concentrated magnetic fields. They are the most prominent visible features on the Sun; a moderate-sized sunspot is about as large as Earth! They occur when strong magnetic fields emerge through the solar surface and allow the area to cool slightly, from 6000 degrees C down to about 4200 degrees C; this area appears as a dark spot in contrast with the Sun (so, yes, the spots appear darker with their lower temperatures). Sunspots rotate with the solar surface, taking about 27 days to make a complete rotation as seen from Earth. Sunspots near the Sun's equator rotate at a faster rate than those near the solar poles. Groups of sunspots, especially those with complex magnetic field configurations, are often the sites of flares. Have a good day and thanks for your question!! Essi 

SCIENTIST: Essi Jones, NOAA Space Environment Center

QUESTION:
What is the worst impact that sunspots have ever had on earth? Ben, Willard Middle School, Berkeley CA 

ANSWER:
Hi Ben! The first thing I should mention is that it is not the sunspots that impact Earth, but in fact it is the solar flares (and other related events) produced by these spots that can have an impact on Earth. We have seen a few events in history that have impacted Earth fairly drastically, but the point that we need to remember is that as technology increases, so do the chances that more systems can be affected by the Sun and its phenomena. I think that one of the most intriguing cases that I've read about is that there are now 4 astronauts that have been up in space (on shuttle missions) and have already received lifetime doses of radiation, due to solar activity! This means that each of these astronauts cannot go back up into space because they have already attained the maximum level of radiation allowable for space flight. This level of radiation can cause radiation sickness and even predetermine cancer. So, this is one of the reasons why it is so important for us here in the Space
Environment Center to monitor the Sun's activities (i.e. so that we can help prevent more astronauts from attaining such high levels of radiation).
Thanks for your question!! Bye! Essi 

SCIENTIST: Essi Jones, NOAA Space Environment Center

QUESTION:
When was the first sunspot observed and what instrument did the use to see it? Song, Beers Street Middle School, Hazlet, NJ 

ANSWER:
Sometimes, when the Sun is very close to the horizon (so it doesn't seem so very bright anymore) with a particularly large sunspot on it, people can see that sunspot without using any instruments (but don't try that at home!). This means that sunspots were probably first observed by some unknown person a very long time ago before humans started to write things down. I have heard of records from ancient China (of about 2000 years ago) that mention "blemishes" of some kind on the Sun, and people think those may have been sunspots, but of course there is no way for us to know for sure. There are also some hints that people in ancient Greece saw sunspots about 2500 years ago, but those are not clear, either. In some cases, people saw a sunspot but thought it was the planet Mercury instead; for instance, Johannes Kepler in 1607. After the telescope was invented in Holland in 1609, proper study of sunspots could begin. The person most often credited with first observing sunspots with a telescope (and recognizing them as spots on the Sun; but don't try this at home either!) was Galileo Galilei from Italy (1564-1642), who is known to have seen them toward the end of 1610, only about a year after the telescope was invented. The Englishman Thomas Harriot
(1560-1621) made a drawing of sunspots he observed on the Sun in December 1610, at about the same time that Galileo observed them. In
those days, there were some more people who claimed to have been the first to have seen sunspots with a telescope, but from the evidence we have available today it appears that credit should be shared by just Galileo and Harriot.

SCIENTIST: Louis Strous, Lockheed Martin Solar and Astrophysics Lab

QUESTION:
When was the first sunspot observed and what instrument did the use to see it? Song, Beers Street Middle School, Hazlet, NJ 

ANSWER:
Ah, sunspots have been known to humans for millennia, the Chinese have records, probably 500 or 1000BC (need to check). These observations can be made 'with the naked eye'; this means using a pinhole to create an image. You can use 2 pieces of paper; make a hole in the center of one, hold it a few inches from the other (outside on a sunny day of course) and look at the image of the sun. By moving the sheets apart, you get a bigger image. Of course all you can see is that the sun has spots, that it is not the 'perfect sphere' that people conjectured in the Dark-Middle Ages. The refinement to our present understanding of sunspots as dark regions with strong, radial magnetic fields probably began last century: I have a reference to a conjecture based on eclipse observations in 1878. The first magnetograph (instrument to measure solar fields based on Zeeman splitting) was built by Babcock at Mt Wilson, CA ~1940. Instruments have been getting better ever since. 

SCIENTIST: Zdneka Smith, NOAA Space Environment Center

TELESCOPES (GROUND BASED)


QUESTION:
How far can the largest telescope see into space? Garrett, Beers Street Middle School 

ANSWER:
The Keck 8-meter telescopes can see about 15 billion light years into space. 

SCIENTIST: Frank Hill, National Solar Observatory, Kitt Peak

QUESTION:
Is the telescope that you use harder to use than the ones we use at home? Does it have similar parts or are all parts different? Victor,
Grade 6, Deer Park Middle Magnet School 

ANSWER:
The main difference between our telescopes and the ones you might have at home is that ours are a *LOT* larger! They also have special instruments, like cameras, filters and spectrographs to collect data with. I think that our telescopes are actually easier to use because we have computers that point the telescope to any object, while you would have to do this by hand with most home telescopes. 

SCIENTIST: Frank Hill, National Solar Observatory, Kitt Peak

QUESTION:
About how many radio telescopes are actively being used to observe the stars? Chris 

ANSWER:
There are around 50 radio telescopes in the world used for astronomy, but some of these (Like the VLA [Very Large Array]) in New Mexico are composed of several smaller telescopes. The VLA has 27 telescopes operating together. 

SCIENTIST: Frank Hill, National Solar Observatory, Kitt Peak

QUESTION:
Which telescope gives the most clear pictures of the Earth? Jeff, Cranbrook MS 

ANSWER:
We usually think of telescopes pointing away from Earth to look at distant planets and stars. We don't have so many telescopes that point at Earth. There is a plan to put a telescope on a satellite that will go out to a place about 1/10th of the way to the Sun and then stay there. The telescope on this satellite will look back at Earth and take continuous pictures. In the days of the Apollo missions to the moon, the astronauts would often take spectacular pictures of the Earth but because they were so close, it did not require a big telescope. They would simply use a normal camera. If you were on the moon, the Earth would be almost 4 times bigger than the moon as viewed from Earth. You can imagine that you would not need a very big telescope to get a good picture. The Shuttle astronauts also take pictures of the Earth but they are so close that they can only see a part of the Earth. To capture details of the Earth from space, many countries send up spy satellites that look down on other countries. They are so good that they can see cars driving around and even people walking. How well they can see is often Top Secret
information. You can get LandSat images of Earth and they are good enough to see houses in but not people. 

SCIENTIST: Rod Viereck, NOAA Space Environment Center

TEMPERATURE OF THE SUN


QUESTION:
How do they know that the center of the Sun is 15 million degrees? 

ANSWER:
The core of the Sun must support the weight of all the layers above it. We know that the core does just! How? Because we do not observe the Sun shrinking in size as a result of a core shrinking due to all the weight above it. How does the core support all this weight? It doesn't have muscles like the cheerleader on the bottom of the pyramid. The core uses pressure as it's muscles. The pressure in the core exactly balances the weight of every layer of it. This tremendous pressure generated in the core corresponds to an extremely high temperature. Now that we've thought about it, how do we get a value for the temperature? Astronomers build a mathematical model which closely resembles the behavior a star using four equations. From these equations they can calculate the temperature, density, mass and pressure at a particular place in the star, say for instance the center of the Sun. 

SCIENTIST: Detrick Branston, National Solar Observatory, Kitt Peak

QUESTION:
What is the temperature of the Sun and how is it determined? Crystal, Amanda, and Rikki Lynn, Beers Street Middle School Hazlet,
NJ 

ANSWER:
The temperature of the Sun at the surface is 6000 degrees. We know this because when we heat something like a steel bar up to different temperatures, it changes color. Well, those colors correspond to specific temperatures. This is because of something called blackbody radiation. The interior of the Sun is much hotter. The center of the Sun is about 15 million degrees. How do we know that? Well, for one thing, the hotter something is the more pressure there is. And then the weight of the Sun pushes down on the Sun with the pressure created by the heat pushing outwards. These must balance exactly. So, if we know what the Sun is made of, and how big it is, and how much it weighs, then we can estimate the temperature in the core. 

SCIENTIST: Doug Biesecker, NASA Goddard Space Flight Center

QUESTION:
How hot is plasma or how hot is the Sun? Robert, Belleview Middle School 

ANSWER:
A plasma is a partially or totally ionized gas: its temperature is a measure of the random energy or motion of the particles. To create a plasma, individual atoms/molecules have received sufficient energy to become ions. In figuring out how much, people speak of the FIP = first ionization potential. It varies according to the kind of gas. Once the plasma is created, its temperature depends on a number of factors: so there is no one answer. For example, the Sun emits the solar wind, a supersonic plasma flow, mainly protons. Near Earth the solar wind (plasma) temperature is ~ 10,000-1000,000 deg K. (ten to the 4th-6th power) But the density is ~ 1/cubic cm, so we will not be scorched! Now the Sun: it has many layers: the level (layer) we see when we look at the Sun is called the photosphere, its temperature is ~6600 degrees Kelvin(deg K). We also call this distance 1 solar radius (Rs). Inside the sun, the temperature is hotter: we can only infer that : ~ 8 million deg K. Going outward the temperature of the sun first decreases to ~4300 (deg K), at 1.1 Rs and then increases to 2 million degrees in the corona (~1.2 Rs). So you
can see that our Sun, a 'ball of gas' is rather complicated. The general temperatures are normal for stars; I don't believe we really know why the
Corona is so hot, but there are theories. 

SCIENTIST: Zdneka Smith, NOAA Space Environment Center

YOHKOH SPACECRAFT


QUESTION:
What does the Yohkoh spacecraft do? What is it used for? Joe, Alex and Brian, Beers Street Middle School, Hazlet, NJ

ANSWER:
Dear Joe, Alex and Brian, I'm sorry it has taken me so long to reply but I had a high school teacher visiting us here to talk about some of the things we do. The Yohkoh spacecraft is primarily designed to look at the atmosphere of the Sun and in particular the hottest part that we call the corona. It was originally flown to study the dramatic explosions on the Sun called "solar flares", which can get to temperatures of 30 million degrees, but it has also been able to look at the hot gas which is almost everywhere on the Sun. The Yohkoh telescopes can see gas as cool as 2 million degrees and as hot as 100 million degrees which allows us to study all parts of the atmosphere. You can learn more about Yohkoh by going to http://www.lmsal.com/YPOP 

SCIENTIST: David Alexander, Lockheed Martin Solar and Astrophysics Lab