TESS found a super-Jupiter in its archives nearly 40,000 light-years away

A planet with 1.6 times Jupiter’s mass and an orbit at a distance comparable to that between Jupiter and the Sun was detected thanks to TESS archival data. TESS is the NASA satellite known mainly for searching for planets that pass in front of their stars. The world, called Gaia23bra b, orbits an orange dwarf star and is nearly 40,000 light-years from Earth.

The case shows how data from a mission designed for one technique can also be used to find planets through another. In an explanation published on July 10, 2026, NASA described the finding as TESS’s first identification of a planet through gravitational microlensing signals. The agency says the research team’s analysis appeared on July 1 in The Astrophysical Journal Letters.

A signal first recorded by Gaia

The first indication of Gaia23bra b appeared in 2023, when the alert system of the European Space Agency’s Gaia space telescope detected a star brightening. Gaia, which had already ended its operations, observed a phenomenon that can occur when a foreground star passes almost directly in front of a more distant one from our point of view.

The gravity of the nearby star bends the light from the background star and can amplify its apparent brightness. This effect is called gravitational microlensing. If the star acting as a lens has planets, they can also alter the observed light and produce brief deviations in the distant star’s brightness.

Gaia’s observations were too sparse to detect the planet, according to Mallory Harris, a doctoral student at the University of New Mexico and lead author of the study. The team then reviewed TESS archival data and discovered that the satellite had observed the same region of sky during the event. Its denser time coverage showed additional features in the light curve that Harris attributes to a planet.

What TESS contributed and what characterizes the planet

TESS—the NASA Transiting Exoplanet Survey Satellite—was conceived mainly to search for worlds using the transit method. This technique monitors the brightness of many stars to detect periodic dimming when a planet passes in front of its star from our perspective.

In this case, the team used TESS observations of a microlensing event. The planet, Gaia23bra b, orbits an orange dwarf star with about 80% of the Sun’s mass. NASA places the system nearly 40,000 light-years from Earth and compares this distance with TESS’s usual search radius of about 150 light-years. The figure describes the contrast highlighted by the agency: the discovery was made much farther away than the region usually covered by the mission’s regular search.

The planet has 1.6 times Jupiter’s mass and an orbital distance similar to Jupiter’s distance from the Sun. Diana Dragomir, a professor at the University of New Mexico and co-author of the paper, said that when TESS was launched, no one expected it to be able to find this type of planet. The agency suggests that other planets detectable through microlensing may exist in its data and may not have been searched for in that way.

Two methods that reveal different worlds

Transit and microlensing detect planets in different ways. The transit method looks for the periodic dimming of a star caused by a planet crossing in front of it. According to NASA, it is especially effective for large planets close to their stars: large worlds block more light, and those in close orbits have more opportunities to pass in front of their stars from our point of view.

Microlensing, by contrast, depends on a close alignment between a foreground star and a background star. The foreground star’s gravity bends and amplifies the latter’s light; a planet around the nearby star can produce an additional signal. NASA’s explanation says that this method can provide the masses and orbital distances of planets that would otherwise be difficult to see, and can reveal worlds that are smaller or farther from their stars.

The contextual figures published by NASA in its July 10, 2026, explanation indicate that more than 6,000 exoplanets—planets outside the Solar System—were known at that time; around three-quarters had been discovered through transits and fewer than 5% through microlensing. These proportions refer to the known exoplanet population summarized by the agency, not to all the planets that might exist.

The limitation of a one-off event

Microlensing can reveal properties of planets that other methods do not easily detect, but the phenomenon has an important condition: events occur only once and do not repeat, according to NASA. This makes it difficult to conduct detailed follow-up observations of the planet using the same signal. For Gaia23bra b, TESS’s coverage during the event was important because it provided more frequent observations than Gaia and made it possible to identify additional features in the light curve.

The finding also illustrates the value of revisiting a mission’s archives with a question different from the one originally asked. TESS recorded the event while observing that region of the sky; subsequent analysis made it possible to recognize its usefulness for studying microlensing. NASA presents this observation as a first case of its kind for the mission and suggests that its data may contain other planetary signals detectable by the same method.

Why combining missions matters

Gaia provided the first indication by detecting the brightening in 2023; TESS supplied denser time coverage of the event by observing the same region. Together, they made it possible to analyze a microlensing signal in the archives of a satellite whose usual method is transit detection. Gaia23bra b, with a mass greater than Jupiter’s and a wide orbit, thus shows how complementary techniques can expand the range of identifiable planets.

The scope of the observation is tied to the event’s conditions: microlensing depends on an alignment from our perspective and does not produce a signal that repeats periodically. Even with this limitation, TESS data made it possible to identify additional features attributed to a planet in a system located very far from Earth.