What do I look for in Mirror size or telescoping power? I know the mirrors are important but I don't know anything about them.
well, if you want to compare a home telescope to a proffesional one, there is one very obvious way to do it:
to buy a proffesional telescope and look through the home telescope too, then compare.
however, a lot of people don't have the money nowadays. so, you can compare the view from your telescope to pictures found on the internet, via google and other search browsers.
if you're using a home telescope, make sure you try not to look into very bright stars in the distance if it can go that far, unless you are sure that it will not damage your eyesight.
