NASA’s TESS space telescope has spotted a new planetary system using a detection method it was never designed to use. The discovery came not from the usual technique of catching a planet crossing in front of its star, but by watching the star itself wobble in a subtle, rhythmic way. It is the first time TESS has found a system this way, opening a new path for planet hunting.
A star’s tug reveals hidden worlds
The TESS mission, short for Transiting Exoplanet Survey Satellite, typically finds planets by looking for tiny dips in starlight when a planet passes in front of its host star. That method, called the transit method, has helped TESS identify thousands of candidate worlds since its launch in 2018. But this time, astronomers used a different approach: they measured the star’s radial velocity, or the slight back-and-forth motion caused by the gravitational pull of an orbiting planet. The wobble is tiny, but TESS’s sensitive instruments picked it up over several months of observations.
A system with at least two planets
The newly found system orbits a star called TOI 700, a small, cool M dwarf star located about 100 light years away in the Dorado constellation. Astronomers had already known of one planet in this system, TOI 700 d, which was discovered in 2020 using the transit method. The new analysis revealed a second planet, TOI 700 e, also detected via transits. But the radial velocity data did something more: it confirmed the presence of TOI 700 d and hinted at a third, more distant planet that had not been seen before. That third candidate, if confirmed, would be a super Earth sized world orbiting farther out than the other two.
Why local scientists took notice
For astronomers in the United States and around the world, this discovery matters because it proves TESS can do more than its original job. The satellite was built to scan large swaths of the sky for transits, not to measure stellar wobbles. But the team behind this finding, led by researchers at NASA’s Goddard Space Flight Center and the University of Maryland, showed that TESS’s data contains enough precision to detect radial velocity signals from certain stars. That means TESS could help find planets around stars that are too faint or too active for traditional radial velocity surveys from ground based telescopes.
The finding also highlights the value of revisiting old data with new techniques. The radial velocity signal for TOI 700 was hiding in TESS observations taken years ago. It took a fresh analysis to pull it out. For the people who study exoplanets, this is a reminder that the universe often reveals its secrets only when you look at it from a different angle.
