In a recent AMA, NASA scientists who search for habitable planets outside of our solar system answered questions from the Reddit community. Their main goal: to seek out a world like ours.

Before the 1990s, scientists didn’t know if there were more than “nine” planets in existence. It wasn’t until 1992 when NASA found evidence of the first exoplanet (meaning a planet outside of our solar system). That discovery changed everything.

Since then, it’s been estimated that there are billions of planets in existence. So far, we’ve only found around 30 habitable planets, but none of them are Earth-like to our knowledge.

Stellar Neighborhood (33 light years from our sun). “P” represents the stellar systems with planets. (Recons Project)

That’s where NASA comes in: They are launching several new projects to scan the sky in ways that we never could before—with the help of infrared telescopes and other new technologies. There are going to be some huge discoveries coming up within the next 10 years.

NASA scientists say:

“It is exciting to think that in the next 20-30 years, we may realistically be able to answer one of the oldest questions of humankind: Are we alone?”

Although we are just at the very beginning of our explorations, we have already discovered some very unusual planets. Remember the planet Tatooine from Star Wars? NASA found a planet similar to this fictional world.

Lucasfilm/Disney

NASA explains:

In fact, they have even found some planets that may be completely covered in water. These are called water worlds (not to be confused with the Kevin Costner box-office bust, as Reddit user strawkastle pointed out).

Unfortunately, NASA doesn’t have a specific plan of action in case we discover some hostile aliens on one of these worlds. WTH, NASA?

Check out NASA’s entire AMA session here.