this National Geographic article, this week many of us should be able to see five planets in the night sky without the aid of a telescope. Reading the article reminded me of some resources for teaching and learning about space that I've reviewed in the past.
Eight good resources for space science lessons.
A Planetarium for Your Browser
Use Google Sky to Know What You're Looking at Tonight
Real World Math has lessons that use the Moon, Mars, and Sky view in Google Earth.