NASA has made an unexpected breakthrough after its Transiting Exoplanet Survey Satellite (TESS) discovered a giant exoplanet using gravitational microlensing, marking the first time the mission has detected a planet through ripples in space-time instead of its usual transit method.
The newly identified world, named Gaia23bra b, is a super-Jupiter with a mass about 1.6 times that of Jupiter and orbits its orange dwarf star at a distance similar to Jupiter’s orbit around the Sun.
Scientists say the discovery was surprising because TESS was designed to find planets that pass in front of their stars, causing small dips in brightness. Finding a planet through microlensing was never considered one of the spacecraft’s strengths. Researchers now believe there could be many more hidden microlensing planets waiting to be uncovered in TESS’s archived observations.
The first clue came in 2023 when the European Space Agency’s retired Gaia spacecraft detected an unusual brightening of a distant star. The event was caused by gravitational microlensing, a phenomenon predicted by Einstein in which a foreground star bends and magnifies the light of a more distant star. When scientists reviewed archived TESS data, they found the spacecraft had also captured the event with much denser observations, revealing the subtle signal of an orbiting planet that Gaia alone could not detect.
Further analysis showed that Gaia23bra b is located nearly 40,000 light-years from Earth, making it one of the most distant planets ever detected by TESS. The planet orbits a star with roughly 80 percent of the Sun’s mass, far beyond the mission’s typical search range of around 150 light-years.
Unlike the transit method, which is best at finding large planets close to their stars, gravitational microlensing can detect planets orbiting much farther away, including worlds that may lie within a star’s habitable zone. The two techniques complement each other by revealing different types of planetary systems that would otherwise remain invisible.
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The discovery also provides a preview of what NASA’s upcoming Nancy Grace Roman Space Telescope could achieve after its planned launch in August 2026. Roman is expected to discover around 1,000 planets through microlensing and about 100,000 more using the transit method while surveying the crowded center of the Milky Way. Researchers believe combining Roman’s observations with TESS data could offer new insights into how planetary systems form and evolve across different regions of our galaxy.
