NASA's TESS Discovers A Nearby Super-Earth That Can Harbor Life

Using NASA’s Transiting Exoplanet Survey Satellite (TESS), astronomers discovered a potentially habitable world outside of the solar system.

The TESS space telescope, which was designed to search for exoplanets, detected the planet in early 2019.

The alien world, named GJ 357 d, is a super-Earth located about 31 light-years away. The exoplanet is more massive than our home planet and has conditions that suggest it could potentially support life.

"This is exciting, as this is humanity's first nearby super-Earth that could harbor life—uncovered with help from TESS, our small, mighty mission with a huge reach," said Cornell University’s Carl Sagan Institute director Lisa Kaltenegger, who is also a member of the TESS science team.

Researchers said that GJ 357 d has a thick atmosphere, so it could maintain liquid water on the surface like planet Earth could. It is also located in its home system’s habitable zone. Astronomers could pick out signs of life in this world using telescopes that will soon be online.

“If the planet has a dense atmosphere, which will take future studies to determine, it could trap enough heat to warm the planet and allow liquid water on its surface,” said Diana Kossakowski of the Max Planck Institute for Astronomy in Germany.

The planet lies in the star system GJ 357, which hosts an M-type dwarf sun that is only about a third of the size of the sun. The distant solar system also has three planets, one of which is the GJ 357 d.

In February, TESS observed that the dwarf sun GJ 357 dimmed very slightly every 3.9 days, which hinted of a transiting planet moving across it. Scientists from NASA’s Goddard Space Flight Center said that planet, GJ 357 b, is a hot Earth about 22 percent larger than our planet.

Follow-up observations and data collected by Earth-based telescopes dating back two decades led to the discovery of the planet’s siblings, GJ 357 c and GJ 357 d. Exoplanet GJ 357 c is at least 3.4 times more massive than Earth and sizzles at 260 degrees Fahrenheit.

GJ 357 d, which lies on the outermost of the system is a super-Earth that could provide Earth-like conditions. It orbits the host star every 55.7 days at a proximity of about one-fifth of the distance between the Earth and the sun.

The researchers published their findings in the journal Astrophysical Journal Letters on July 31.