NASA's TESS Mission Finds Its Tiniest Alien Planet Yet

The small planet is around 80% the size of Earth.
The small planet is around 80% the size of Earth.
(Image: © NASA's Goddard Space Flight Center)


NASA's Transiting Exoplanet Survey Satellite (TESS) has discovered a tiny planet — the smallest one it has found to date.

The planet, named L 98-59b, measures between the size of Earth and Mars and is around 10% smaller than the previous record holder discovered by TESS, which is around the same size as Earth, according to a statement by NASA.

"This system has the potential for fascinating future studies," Veselin Kostov, an astrophysicist at NASA's Goddard Space Flight Center in Maryland who helped spot the new planet, said in the statement.

Related: NASA's TESS Exoplanet Hunting Mission in Pictures

L 98-59b is orbiting a nearby bright star, which is around one-third the mass of our sun. TESS also found two other planets in the same system, which are around 1.4 and 1.6 times the size of Earth, according to NASA. However, scientists aren't sure yet whether these planets have atmospheres and, if so, which gases are present in them. 

None of the three planets are likely to host life; they all lie outside their star's habitable zone, the range of distances from a star where liquid water could exist on a world's surface, NASA officials said.

Dwarf stars like the one hosting these three planets make up three-quarters of the stars in our galaxy, and therefore scientists want to learn more about the worlds that form around them.

TESS launched in April 2018 with a key goal of developing a catalog of small, rocky planets that orbit around nearby stars. Scientists' plan is to then revisit those planets with the James Webb Space Telescope once that instrument launches in 2021 in order to help us better understand our own solar system, as well as its surrounding universe.

"We still have many questions about why Earth became habitable and Venus did not," Joshua Schlieder, another astrophysicist at Goddard and researcher on the project, said in the same statement. "If we can find and study similar examples around other stars, like L 98-59, we can potentially unlock some of those secrets."

The discovery is described in a paper published on June 27 in The Astronomical Journal.

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