If you really wanted to download Celestia after looking at the last tech tip but you're having trouble with it you might want to check out these websites to placate your astronomy needs:
Google Moon: http://moon.google.com/
Google Mars: http://www.google.com/mars/
Need a wider view? Try the Hubble Telescope Gallery: http://hubblesite.org/gallery/
These websites are available to anyone with an internet connection and do not require any downloading.