Like NeutronStar said... Asteroids already exist in Universe Sandbox.
Right click and select 'Asteroid' from the 'preset' drop down list in the top left under New Bodies.
A meteor is simply an asteroid that enters the Earth's atmosphere. (But it would be cool if it broke up and left a fiery trail, on the to-do list)
Here's a great video of a space craft reentering our atmosphere (so kind of like a meteor):
http://www.space.com/common/media/video.php?videoRef=SP_080930_atv_reentryAuroras are the result of the interaction of the earth's magnetic field and solar wind. It's a great idea, but I imagine that the cost/benefit ratio would be high to make something realistic. I'll think about it some more.