TESS finds a small planet that sizes between Earth and Mars

NASA's TESS spacecraft has been finding exoplanets frequently since it began operations. TESS, or Transitioning Exoplanet Survey Satellite, has now discovered the smallest planet it has ever found. The tiny world is called L 98-59b and orbits a distant star along with two other planets dubbed L 98-59c and L 98-59d.

Scientists say that the system where the small planet, which slots between Mars and Earth in size, was found has potential for future study. Discovering small planets is difficult to do, and scientist say for atmospheric studies of small planets, scientists need short orbits around bright stars, but the planets are difficult to detect.

Planet L 98-59b is only 80% of Earth's size and is 10% smaller than the previous smallest planet discovered by TESS. The star it orbits is called L 98-59 and is an M dwarf star that is about 1/3 the mass of the Sun and is 35 light-years away from Earth in the constellation Volans.

NASA's Kepler mission has discovered an even smaller exoplanet dubbed Kepler-37b that is only 20% larger than the Moon. As for the other two planets in the newly discovered Tess system, L 98-59c and L 98-59d are larger than the Earth at about 1.4 and 1.6 times respectively. TESS discovered all three planets by looking at transits, or periodic dips in the brightness of the star caused when the planets pass in front of it.

Tess monitors a sector of the sky for 27 days at a time. When Tess finishes its first year of observations next month, the L 98-59 system will have appeared in seven of the 13 sectors that make up the southern sky. That will allow the scientific team pouring through the data to search for additional planets that may have a gravitational impact on the planets it knows about.