Star trail photographs usually use long-exposure times to capture the path that stars take across the night sky. (Actually the earth is what’s moving) They make for amazing photographs that almost look like a special effect from a movie. Would you like to be able to capture a shot like this?
There’s a lot you need to know to make this type of photograph turn out, like why a whole bunch of 30 second exposures is really better than one long one. Or why cold nights are much better than warm ones for capturing the perfect image.
You’ll also need technical details like why you need a longer time for wide angle lenses and what the best ISO is.
It’s a lot information, so I think I’ll just show you the video tutorial I made on the subject. Click here to check it out. 
It’s posted on my OTHER website, Backcountry Gallery . Feel free to snoop around there once you’re done watching the video 😉