NASA recently announced that they have discovered 7 potentially habitable exoplanets orbiting a nearby dwarf star 40 light-years away from Earth. NASA believes that all of them might have liquid water.

Thomas Kutcher, associate administrator of the Science Mission Directorate at NASA Headquarters in Washington, said that, "the discovery gives us a hint that finding a second Earth is not just a matter of if, but when."

All 7 planets have been nicknamed "Earth's 7 Sisters" due to the fact that they are all around the same size as Earth, along with them potentially all having rocky surfaces.

3 of the planets are in what is called the "Goldilocks Zone" or the habitable zone, which is the area around the star where liquid water is most likely to exist.

Astronomers have revealed that the planets revolve around a star that is way longer than our sun. They say it could burn for another 10 trillion years, which is 700 times longer than the age of the universe.

The planets are so close to the dwarf star that the shortest orbit takes 1.5 days, while the longest takes 20 days. Scientists also say that the planets are most likely "gravitationally locked" to the star, meaning one side of the planet always faces the star while the other always faces away. Basically, these planets orbit their sun just like our moon orbits Earth.

The proximity to the sun also affects the light received from the sun as well as its size. On Trappist-1f (the 6th planet from the sun), you would only see about one-two hundredth the light we see from our sun. However, this sun would appear three times as wide as our sun.

Scientists hope to study the gases on the planets to determine if there is life on them or not. One scientist said that if they can discover oxygen, methane, ozone, and carbon dioxide (within certain proportions) that would indicate "with 99% confidence" that plants and/or animals live on the planet.

It seems like NASA gets closer to discovering alien life with each passing day. Will they be able to find life in our lifetime?