A Primer for Teachers

>>(Narration over opening titles)

In this, the first of two programs specifically designed to help teachers implement Passport to the Solar System, you'll find...

An introduction to our Solar System AND to the researchers whom you and your students will meet on camera...

A review of the most important scientific principles that have shaped our Solar System...

...And a look at some amazing new images from recent NASA missions.

>>Main title

>>Graphics table of contents
Educator Program A
Our Solar System
Meet the Scientists
Key Concepts for Undestanding the Solar System
Researchers and Educators

>>Our Solar System:
An Overview from segments of several PTSOLAR videos

In 1977, two spacecraft began an epic journey of discovery that would take them much farther than any Columbus down here on Earth.

They were called, appropriately, "Voyager 1"

...and "Voyager 2."

I took advantage of a rare alignment of the planets to borrow gravitational energy from each encounter and slingshot itself onward to visit all the giant planets.

Just before Voyager 1 passed beyond our solar system en route to the stars, astronomers on the imaging team suggested turning it around for the first ever "family portrait" of our solar system.

>>title: GAS GIANTS

The camera panned across the sky, capturing "long shots" of our system's 4 gas giants: Uranus, Neptune, Saturn, Jupiter.


Then, far tinier and harder to see, the 4 terrestrial, or "Earthlike" planets: Mars, Earth, Venus, and Mercury.

Back there at the center, our Sun, looking just like the average star it is.

Left out of this picture, icy Pluto, the 9th planet.

The Voyager images showed us how vast space is, and how small and isolated our solar system.

But it also showed us that it is a system, circling round our star, bound together by the master force of gravity.

Let's meet the member of our family, in close-up...

At the heart of the solar system is our star, the Sun.


The Sun contains 99.8% of all the mass in our solar system.

One million Earths could fit inside the Sun.

Its visible surface is nearly 6,000 degrees Kelvin.

The Sun's light and heat power heat on Earth, and its radiation stretches out to the very edge of the solar system, where the realm of the Sun becomes inter-stellar space.

Next out from the Sun, Mercury, revolving once around the Sun every 88 days in a very elliptical orbit.

2nd smallest of the planets, temperatures vary from 400 degrees Celsius to minus 170, depending on which heavily cratered face looks toward the Sun.

2nd rock from the Sun, Venus.

It's about the same size as Earth, but it's a hot and hellish world with thick clouds of sulfuric acid, and surface temperatures of over 450 degrees Centigrade.

A runaway greenhouse effect makes Venus hotter than Mercury even though it's twice as far from the Sun.

The Magellan spacecraft used radar to peer through the clouds revealing more than 100,000 volcanoes and a mountain taller than Mt. Everest.

3rd rock, Earth...

Unique in the solar system for plentiful liquid water on its surface, and as yet, the only planet where we know for sure that life began and evolved.

Perhaps, by understanding the processes that shaped our neighbors, we can keep our home world habitable...

One out from Earth, Mars, the red planet, now locked in an icy deep-freeze.

Half the size of Earth, Mars has giant volcanoes...

A vast canyon that would stretch clear across North America...

Evidence of running water from long ago...

And perhaps, still liquid water deep underground.

Images from the recent Global Surveyor and Pathfinder missions make us want to visit Mars again with rovers and soon with human explorers to find out whether life ever began here, and perhaps, still lingers in some hospitable oasis.

Between Mars and Jupiter, the asteroid belt; tumbling leftovers of planets that never quite got it together, or remnants of worlds that fell apart.

Then, the 4 gas giants, studied in detail by the Voyager spacecraft.

Jupiter, king of the planets, 2nd most massive object in our system after the Sun...

Perhaps there's a solid core of rock and liquid metal, but here, the surface is all clouds in motion, including this swirling hurricane, the Great Red Spot, a storm that has lasted more than 300 years.

Voyager showed us that Jupiter's moons are as exciting and dynamic as the planet itself.

In all, Jupiter has more than 17 moons, stay tuned for more, and a faint ring system.

Next out, Saturn, with the largest and most finely patterned rings in our solar system.

Also a gas giant, Saturn is squashed, smaller from pole to pole than around its equator.

Voyager 2 used Saturn's gravity to boost it on to Uranus.

This planet is the only one whose pole, rather than equator, sometimes faces the Sun, for reasons we still don't know.

Like the other gas giants, Uranus has rings, and more than 20 moons, the most of any planet in the solar system.

Last gas giant, Neptune, named for the god of the sea, and, appropriately, bluish in color.

Neptune has the fastest winds in the solar system, more than 2,400 kilometers per hour. And this "great dark spot," seen by Voyager, now seems to have disappeared.

Usually the outermost, and certainly the smallest planet in our system, is Pluto, the only world never visited, so far, by spacecraft from Earth.

These images from the Hubble Space Telescope show seasonal changes on its surface as gases freeze out in winter.

Pluto is mysterious, but we do know it has a moon, Charon, about a third its size, the largest satellite relative to its parent planet in the solar system.

-Torrence Johnson, Galileo Project Scientist:
"...You have to realize that doing science is not just looking at a 'gee-whiz' picture or tromping around a geologically interesting place with a rock hammer... It's understanding why things are the way they are, and I think you start with curiosity and then you get a real intellectual fire when you realize that these things are explicable, you can write down equations that explain these things that you're seeing. It's not just random, and it's not just 'oh well, that's neat.' You say, 'that's neat and that's neat because it happens because of this, and, oh by the way, that means that this other place might have that going on.' And you can start really understanding this place we're all living in, the Universe, in a way that people who do not understand those fundamental principles can never really appreciate (that) …is one of the things that drives a sort of a missionary zeal in scientists to try to get across the excitement of doing science, not the dullness of just learning numbers or memorizing facts and figures."

-Claudia Alexander, U.S. Project Scientist, Rosetta comet mission:
"The background that I came from, a lot of kids didn't even come from the best schools, they didn't come from privileged backgrounds where you had the luxury of just being able to study. And I want to be able to bring to those kids ways of learning because along the way I learned ...I actually learned by talking. I learned by doing activities with people and working with my hands on projects. And when I was coming up through school that wasn't the way that science was taught. The way that science was taught is that someone was up at the board and lectured, usually with his back to the audience and there was no chance for interaction. And I had difficulty learning. So I learned and also other educators have learned that the way to teach science better is to actually involve people."

>>leading researchers logo
Leading Scientists Speaking Directly to you and your students

These are some of the leading space scientists appearing in Passport to the Solar System:

You and your students can find out more about them, and their projects, online.

Claudia Alexander has a key role in future comet missions, and also works with the Galileo spacecraft...

Andy Cheng is project scientist for the "NEAR" mission, studying asteroid 433 Eros...

Chris Chyba, from the SETI institute, is an expert on life in the Universe, and comparative planetology...

From NASA's Jet Propulsion Laboratory, Mars Rover scientist, Joy Crisp...

Astrophysicist Craig DeForest, formerly from NASA's Goddard Space Flight Center...

Project manager for the current Stardust mission to a comet, Tom Duxbury...

Mars program scientist at NASA Headquarters, Jim Garvin...

Pathfinder project scientist, Matt Golombek, who provides an overview of mission results in program 4...

Comparing weather on the gas giants and Earth, Heidi Hammel, formerly of MIT...

Mars mission designer Wayne Lee, who's literally written the single best book on the science and technology behind spacecraft exploration...

Torrence Johnson, project scientist for the Galileo mission to Jupiter and its moons, and also a member of the Voyager imaging team...

Rob Manning, one of JPL's lead engineers for future Mars missions...

Looking for solar systems beyond our own, Geoff Marcy, who with his team has discovered more new planets than any one else on Earth...

Ken Nealson, a microbiologist heading up JPL's Center for Life Dtection...

Solar scientist, Art Poland, from NASA Goddard...

Pathfinder project manager, Tony Spear...

And last, but by no means least, Barbara Thompson, a member of the "SOHO" science team working on future solar missions at NASA HQ.

-Claudia Alexander:
"I want the average person when I go to the grocery store and I say I work for NASA, they're very excited but they need to be able for me to tell them what I do in the language that they communicate in…"

KEY CONCEPTS that explain the solar system

Those are some of the researchers participating in this series.

What are some of the key scientific concepts that make our solar system comprehensible, and which your students will experience during the 8 fifteen minute programs?

>>name title:
-WAYNE LEE, Mission Designer
Jet Propulsion Laboratory, NASA/Caltech
"The most noticeable force that shapes our solar system, of course, is gravity... Gravity is what keeps all the planets in orbit around the Sun. It's what keeps us glued down to the surface of the Earth.

"It keeps us from floating away as we're trying to walk to school every day. It keeps your peas on your dinner plate so you can eat them. It turns out that if the Sun did not pull on the planets with its gravitational force, they would just fly off into the Universe never to be seen from again.

"I'd say the second fundamental force that shapes the solar system is probably what we call the 'nuclear force.' And the nuclear force is what allows fusion to occur inside, deep inside the Sun. And, of course, nuclear fusion is the process that produces ...the heat and light that comes out of the Sun and warms all the planets."

>>title: GRAVITY
>>title: FUSION

Gravity... and nuclear fusion in a star...

These are the forces of nature which make and shape a solar system... And the result?

...Nine planets, millions of asteroids, and comets

...and, down here on Earth, life, consciousness, and curiosity...

-Chris Chyba:
"I would say that the way to think about a planet is... it's a collection of rock and liquid and gas that's gotten big enough to be spherical, to be in the shape of a sphere.

"If you're the size of a small asteroid, you don't have to look anything like a globe, like a sphere. You can look like a potato or a dumbbell or anything else because the gravity's not strong enough to sort of smooth out the high spots, to pull the high spots in and compress you down into a globe."

What are the forces which make these four worlds so different... in temperature craters, liquid water... life?


First up, a pretty basic concept- the size of the planet. That turns out to have consequences for just about everything...

-Chris Chyba:
"A world that's small cools down much faster than a world that's big, and we're all familiar with this if you heat up a big potato in your oven and a small potato, the small potato is just going to cool faster.

"So our Moon, the Earth's Moon, cooled really quickly.

"Mars, which is bigger than the Moon, but still much smaller than the Earth, cooled less quickly but also cooled off, and the Earth is still geologically active, it's still hot inside."

A planet's distance from the Sun may also be enough to seal its fate.

-Chris Chyba:
"Mercury is so close to the Sun that it's simply uninhabitable. If it did have an atmosphere it would lose it... the solar wind from the Sun, charged particles would strip Mercury's atmosphere quickly. It's just too close to the Sun and it's too small a world."

The size of a planet helps determine its temperature... and its size and mass also affect its gravity, which helps it keep an atmosphere, or allows it to leak away to space.

-Chris Chyba:
"What does all that mean? One thing that means is that the Earth is still replenishing its atmosphere. Volcanoes on the Earth are still belching carbon dioxide into our atmosphere, so we actually have a carbon dioxide cycle on the Earth where the volcanoes put the CO2 into the atmosphere, rainfall washes it back out, and we kind of maintain a balance of the right amount of carbon dioxide, and incidentally the right amount of water vapor, to give us an amount of Greenhouse Effect that's just right for liquid water to exist."

A greenhouse on the surface of the Earth helps plants grow by allowing the heat and light of the Sun in through a glass roof, but reducing the amount of energy re-radiated back to space. That's why a greenhouse is warmer in winter than the air outside.

A planetary greenhouse effect is caused when gases in the atmosphere drive up surface temperatures by allowing in solar energy, but cutting back its re-emission.

Just as in a greenhouse, the balance between incoming and outgoing heat is critical for living creatures.

It's possible to make things too hot... or too cold.

"If a planet cools off and stops being able to put carbon dioxide into the atmosphere because volcanism shuts down on that planet, then the planet can't maintain the greenhouse, and that's what went wrong with Mars. There used to be the biggest volcanoes in the solar system but they're all dead now... and now the world is freeze-dried. It's become a kind of barren desert at its surface.

"Volcanism on Venus kept putting carbon dioxide into Venus' atmosphere. But what went wrong on Venus is that Venus was so close to the Sun that Venus lost its oceans. The oceans evaporated, they went up into the atmosphere. The snlight breaks up the water molecules into hydrogen and oxygen, the hydrogen can leak out the top of the atmosphere, and once that happens the water's gone, that's it, end of story.

Once Venus lost its water, it was no longer able to remove the carbon dioxide from its atmosphere, so the greenhouse effect on Venus went haywire in the opposite direction that it went haywire on Mars."

>>titles pop on one at a time:

Asteroids... Comets... Meteors... Meteorites... Let's define our terms!

>>name title:
Project Scientist, NEAR
Johns Hopkins Univ / APL, NASA
"Asteroids are primitive objects, many of them left behind from the formation of the solar system.

"The planets condensed out of a ball of gas and dust... some of them never survived the process.

"They grew up to almost the size of planets, and they were crashed into at high speed by another forming object and broken into pieces again."

Others formed into bigger objects, and grew large enough for some planetary processes to begin, with internal heating separating their materials into distinct and differentiated layers.

Some of these then smashed into others and broke apart once more into smaller chunks.

>>title: COMET

Comets also contain dust, but they're characterized by larger concentrations of water ice and frozen gases.

>>name title:
US Project Scientist, ROSETTA Comet Mission, JPL, NASA / Caltech
"When we see it going around the Sun, a comet will put out a big tail, in fact it puts out two tails..."

When comets pass close to the Sun, the gases begin to heat up and stream back behind the nucleus, or head, of the comet and form a tail.

-Claudia Alexander:
"One of the tails is made out of water, and one of the tails is made out of dust. And it goes around the Sun, the tail gets longer and longer, and then as it goes away from the Sun, the tail diminishes until there's no tail at all."

>>title: METEOR

A meteor is what we call an object from space passing through Earth's atmosphere... burning up from friction as it goes.

>>title: METEORITE

And a meteorite, like these being gathered in Antarctica, is what we call a chunk of one of these objects when it falls to Earth.

Torrence Johnson is project scientist for the Galileo mission to Jupiter and its moons, and has also worked on the Voyager mission to the giant planets.

Out here, the planets aren't just bigger, they're made of different stuff- gases and ice, not rock and iron.

>>name title:
Project Scientist, Galileo, JPL, NASA / Caltech
"Until you got beyond the asteroid belt the temperatures weren't low enough to allow the condensation of the more volatile materials. Once you got to the point where you could condense water, wow, you get another big admixture of mass immediately.

"So a typical body that condenses just after you get to the point where you can have frozen water is a body that's about twice as massive as one you've got just inside the water line.

"In addition to that you've got all this extra gas and dust floating around. And the larger planets started, when they started forming, they grabbed even more of this, and they've got enough gravity that they can grab onto all this material out there, including the gases hydrogen and helium. And so you get these massive gassy bodies with icy worlds around them."

Perhaps the gas giants and their alien moons seem, well, "alien," far away, unconnected to Earth...

But understanding how they work, and their strange weather patterns, just may produce some fundamental insight into the way our home planet behaves.

>>name title:
Space Science Institute, Boulder, CO
"One thing that we all care about is the weather. And we care about the weather on the Earth the most. But what makes weather is gases and clouds. And the reason the weather on the Earth is hard to predict is because we have oceans and continents that interact with our atmosphere. That makes it very hard to predict the weather, as we all know.

"But if you take a planet like Jupiter or Neptune, you don't have continents and you don't have oceans, all you have is gas, all you have is atmosphere. And therefore it's a lot easier to model the weather on those planets. But it's the same physical process. It's the same kind of thing happening whether it happens on the Earth or Neptune.

"Therefore by studying weather on Neptune we learn about weather in general, and that helps us understand the weather on Earth better."

Seeing planetary processes played out on the large screen of these giant worlds, we may recognize some laws of nature for the first time.


Let's find out what it takes to see the Universe.

>>chapter head: SEEING THE UNIVERSE

Think of a rainbow, the raindrops spread out the Sun's white light into different colors, or wavelengths.

All those colors from red to blue were in there, all the time, "hiding" in the white light.

A glass or plastic prism, or a diffraction grating, performs the same function as a raindrop... but more efficiently.

The great mathematician, Isaac Newton, was the first to experiment systematically with light this way, and to describe this unvarying pattern of colors.

What we see is called the visible spectrum... but the full electromagnetic spectrum is much wider, and many celestial objects such as exploding stars and galaxies emit most of their energy at wavelengths we can't sense with our unaided eyes.

However, the water vapor in Earth's atmosphere that makes life on Earth possible degrades or cuts off some of these wavelengths.

To see the full spectrum, we have to climb above the clouds with balloons, or planes, or-better yet-spacecraft, to study the heavens.

Even then, and even with a powerful instrument like the Hubble Space Telescope, you get, at best, distant, wide shots of the planets of our solar system.

For close-ups, revealing the secrets of water on Mars...

Or clouds on Neptune...

Or rings around Saturn...

You have to send spacecraft to those planets.

And that means putting not just Newton's laws, but many other scientific principles to work.

>>name title:
Mars Mission Designer, JPL, NASA / Caltech

"When you send a spacecraft to another planet, let's say Mars, you actually have to apply almost everything you know about basic physics. First job is to get the spacecraft off the surface of the Earth. We do that with a rocket. A rocket is a device that operates on one of Newton's fundamental laws, 'for every action there is an equal and opposite reaction.'

And so a rocket operates by expelling hot gas, out, outside of it and the hot gas in turns pushes back on the rocket and makes the rocket rise into the air.

"Once you get the rocket into space, the next job is to get it to Mars, and that's where Kepler's laws come in. It turns out that Kepler was an astronomer a long time ago, I think 500 years, that discovered that all objects move around the Sun in orbits that look like ellipses. Now (an) ellipse, of course, is a squashed circle. And what we do is that we put the rocket in an orbit around the Sun that will eventually intersect the orbit of Mars. And it turns out you can compute what this orbit looks like using Kepler's laws.

"So you can see by getting something from the surface of the Earth to Mars, we've used Newton's laws, we've used Kepler's laws, and we've solved some mathematical equations governing motion."


"There are two reasons why you need to explore the solar system if you want to understand the Earth. The first reason is very straightforward: if you want to understand a particular region of the Earth, you need to understand the surrounding region to understand its environment. If you want to understand a planet in our solar system, you have to understand the solar system. That's what sets the conditions for that planet.

"The second reason we need to understand the other planets to understand the Earth is because we can't do experiments with the Earth. There's a sense in which we are doing a huge uncontrolled experiment with the Earth right now by pumping greenhouse gases into our atmosphere, but there's no control for that experiment. We don't know how it's going to come out. We can get insight into those questions by seeing how other worlds evolved.

"We can look at Venus and see what happens when you have a runaway greenhouse effect.

"We can look at Mars and see what happens when you have too little greenhouse effect.

"Even though we can't do experiments with the Earth, we can do comparative planetology and learn about what might happen or what could happen on a world like the Earth by looking at other worlds where those things have already happened."


The scientists participating in "Passport to the Solar System" are all committed to education and outreach as well as to their cutting-edge research.

We thought you and your students would be interested in their thoughts on teaching and learning...

-Wayne Lee:
"When I was in the third grade, I think it was back in 1975 or so, one of my teachers showed me an encyclopedia, and it was talking about how NASA sent Apollo astronauts to land on the Moon, and I though, oh boy, that's a fun thing to work on. And I was really disappointed when he told me, 'well, they did that back in 1969, that was before your time.' So I thought to myself, well, what would be just as fun? And I thought, well, maybe if we got to send spacecraft to Mars, that would be fun. And so I said to myself, boy, I'd really like to do that. And so I studied hard and here I am thirty years later getting to send spacecraft to Mars."

-Claudia Alexander:
"There is really no one path to becoming a scientist. It's not like you can go to school and take 'scientist classes.' There are lots of different paths, and so basically what you need to do is do what interests you. But make sure that you have all the math and all the chemistry and all the physics that you can take."

-Torrence Johnson:
"Kids that are excited by their first look through a telescope, their first look at data from the spacecraft, frequently want to just dive right in and get more of that. But you do have to put it all together, and that means understanding and going through the process of learning about how mathematics, which is the language of science, works with things, taking those basic courses in physics and chemistry, and always keeping in mind the goal that you're going to use this, it's not just dry facts, you're going to use this to explore and understand what you're seeing in the Universe."

-Claudia Alexander:
"If you pursue those subjects and also the subjects which interest you, I mean for you... it might be some of the engineering challenges, it might be how do you make a spacecraft lift off the ground safely, how do you actually make something land on the surface of Mars, it's quite different from landing on the Earth. Landing with the rockets pointed down, those might be the kind of questions that you might want to answer. And so you might study aerodynamics instead of geology when you get into school but that doesn't mean that you can't ultimately be a planetary scientist."

-Wayne Lee:
"And I want to let you kids know out there to always follow your dreams, because when I was in college, one of my professors asked me, 'well, what do you think you'd want to do for a career,' and I said, 'you know I'd like to be able to send things to Mars.' And he looked at me and he said, 'you know, nobody ever gets to work in that field.' And I'm telling you that's not true. People get to work in the space program and maybe one day it'll be one of you guys out there."

-Claudia Alexander:
"When you're a scientist, you keep learning... your whole life, into your 80s. You keep learning everything, and so eventually you will learn all the things that you would have learned if you had taken a different route. And so it doesn't really matter… but what does matter is that you have to have math and chemistry and physics."

>>Name title:
-KEN NEALSON, Director, Center for Life Detection, JPL
"Well I think that anyone would like to be involved with missions to the unknown. It's this kind of exploration stuff that I find very exciting. And the notion that we could actually look for life in samples from places that have never been touched before, and on other planets with remote instruments. I can't imagine anyone wouldn't be excited about that and wouldn't want to join the effort."

For all we've found out about the solar system in the past decades, there's still much more to discover...

And that takes giant telescopes all around our planet...

Spacecraft in Earth orbit, silicon eyes turned to the heavens...

And robots, sent on missions far beyond Earth, out to the planets of our solar system.

But above all, it takes men and women with brains and imaginations, curious, excited, and committed...

They, and all of us with open eyes and curious minds, are part of the cosmic evolution of the Universe.

We are, indeed, to paraphrase astronomer George Wald, a way for the solar system to know itself.

This... is our neighborhood... This is where we live, and we're beginning to understand it as never before.