Scientists at the National Aeronautics and Space Administration (NASA) made an earth shattering, or perhaps earth creating, discovery.

The announcement, made by NASA Associate Admin Thomas Zurbuchen, revealed the discovery of seven new earth sized planets revolving around the star 2MASS J23062928-05022885. The star is now known as TRAPPIST-1, named after the TRAPPIST telescope that discovered it in 2013. NASA announced the planets on February 22nd, 2017.

TRAPPIST-1 is also a planetary system revolving around the star, which is about one twelfth the size of our sun and nearly 40 light years away. While that description may not make TRAPPIST-1 seem like much, the system is actually home to the seven new groundbreaking discoveries: exoplanets.

An exoplanet is simply any planet that orbits a star outside of our solar system. Thousands have been discovered over the years, whether it be by NASA’s Kepler and K2 missions or the work of the European Space Agency. However, the exoplanets announced on February 22nd are different in a few very important ways.

For one, all seven of the exoplanets in TRAPPIST-1 are similar to the size of Earth. According to TRAPPIST-1’s official site, the radii of the planets fall within a range of 0.76 to 1.13 when relative to Earth’s radius of one. Their masses have larger differences, ranging from 0.41 to 1.38 on the same scale. The planets being similar to Earth in size and mass is important because it foreshadows that at least some of the planets may have similar atmospheres and surfaces to Earth.

Along with their similarities in size, NASA believes six of the planets to be in the range of temperate surface temperatures, with three of the planets receiving the about same amount of energy from their sun as the planets Venus, Mercury, and Earth receive from ours. Temperature is an important factor in determining whether or not planets could be inhabitable, and it looks like at least three of TRAPPIST-1’s planets pass the test.

Another important discovery about the planets, and factor in life sustainability, is that the same three planets with temperate climates also appear to have rocky surfaces. Earth has a rocky surface as well, and a rocky surface is what could possibly harbour liquids. As many scientists say, water is what can determine if life is even possible.

However, the TRAPPIST-1 planets are different from Earth in some significant ways. For example, although the planets are similar to ours in temperature, it is likely they would be slightly cooler. This is due to the fact that the star the TRAPPIST-1 revolves around is about one eighth the size of our sun. Additionally, the orbits of the TRAPPIST-1 planets are far shorter than the planets in our solar system, with the longest orbit being only 20 days.

Despite the notable differences, scientists are still excited about the discoveries. The planets in the TRAPPIST-1 system, according to Zurbuchen, have the most potential for life of any of the planets they have seen outside of our solar system. The exoplanets drive in a point that NASA scientists have been making for a while: that finding extraterrestrial life is not an if, but a when.