For the first time, NASA's Transiting Exoplanet Survey Satellite (TESS) has identified a planet using gravitational microlensing, a technique that relies on the warping of space-time predicted by Einstein's theory of general relativity. The discovery, announced in early 2026, marks a new capability for the planet-hunting telescope, which typically finds worlds by detecting the slight dimming of a star when a planet crosses its face.
The newfound planet, designated TIC 121088159 b, is located about 10,000 light-years from Earth. It was detected when the gravity of a foreground star and its planet acted as a lens, magnifying the light from a more distant background star. This brief brightening event, observed by TESS in 2023, revealed the presence of the planet through a characteristic distortion in the light curve.
Gravitational microlensing is particularly sensitive to planets that orbit far from their host stars, unlike the close-in planets TESS usually finds. This discovery demonstrates TESS's ability to contribute to microlensing studies, which are typically conducted by ground-based surveys. The planet is estimated to be roughly the size of Jupiter, with an orbital distance similar to that of Uranus in our solar system.
The finding was confirmed through follow-up observations by ground-based telescopes, including the Las Cumbres Observatory network. The research team, led by scientists from the Massachusetts Institute of Technology, published their results in The Astronomical Journal in June 2026.
