Aliens have become a staple of sci-fi thrillers, but is it realistic to assume that an advanced alien civilization would travel all the way to Earth just to destroy us? Scientists estimate that as many as 30 percent of the sun-like stars in the galaxy have Earthlike planets. And Earth is a little worse for the wear these days, so what would this intelligence have to gain?

Here are 10 more probable reasons aliens would invade our planet, courtesy of National Geographic:

1. Earth has some unique resource they can’t find closer to home. Let’s be honest—wiping out civilizations for a resource or mineral isn’t a completely foreign concept.
2. They want to prevent a mass extinction of other species. Maybe its rhinos or bees they really want to save!
3. They want to enslave or domesticate us. Human capital at its most extreme?
4. They want us for food. We would provide millions of meals.
5. They want our DNA. Are some of our genes valuable to extraterrestrial species?
6. We pose a threat. We already know we’re prone to violence–would aliens want to wipe us out before we bring war to space?
7. Earth is in the way.
8. They’re preparing for an even bigger war. Let’s not forget that in 1937, German bombers destroyed Guernica just to prepare for future war against the French, British, and Americans.
9. They want revenge.
10. Just for fun.