QUESTION:  
Besides the sun appearing smaller, how would sunrises and sunsets on Mars
differ from those on Earth?

ANSWER from Jim Murphy on February 16, 1997:
I'm quite impressed with you realizing that the Sun will appear 
smaller from Mars than it does from Earth...way to go !!

I can think of a few differences in the appearance of sunrise on Mars 
compared to Earth:

1) on Earth, we actually see the rising sun a bit earlier (a few 
minutes) than it actually appear above the horizon.  This is due to the 
light from the Sun being 'bent' by the Earth's atmosphere so that we see 
the light before we would see it if it came on a straight line from the sun.
Since Mars' atmosphere is less massive than ours here on Earth,  I 
think the amount of bending might be reduced, and thus we might see the 
sunrise 'later' (closer to the time it comes over the horizon) than on 
Earth...

I'm not absolutely sure this is in fact true.  Maybe you can find a more 
definitive answer and let me know !!

2)  since Mars' atmosphere generally has some dust in it, and 
this dust scatters the sunlight (like clouds and dust here on Earth), the
rising and setting Sun might appear more red than a typical sunrise or 
sunset here on Earth.   I know I saw a few sunrises and sunsets in the middle
1970's in New Orleans when we were having a 'dust storm' which 
originated in western Texas, and we had some terrific red sunsets (the 
sunrises might also have been red, but I was asleep when they occurred).  
In much the same way, we can get some pretty spectacular sunsets here on 
Earth after a volcano explodes, dus to all the dust injected into the
upper atmosphere by the eruption

3) since the apparent size of the Sun is smaller from Mars, and 
since Mars spins at a slightly faster rate than does Earth, and, if my 
thought above about less scattering on Mars due to its less massive 
atmosphere is correct, the time require for the enitre sun to become visible
during sunrise (or to disappear during sun set) will be shorter on Mars 
than on Earth.

Thanks for the terrific question, Ian.   I hope you enjoy studying 
Mars and the other planets in the solar system !!

Jim Murphy