First planet around a single star seen to stop crossing its face

Astronomers have watched a planet around a single star stop crossing in front of it for the first time. The planet, TOI-2535 b, is a hot Jupiter: a giant gas planet on a tight orbit close to its star. It used to dim its star on every orbit. Over seven years its path across the star's face slid toward the edge and then off it, and in March 2026 NASA's TESS space telescope saw no transit at all.

The peer-reviewed study, led by Samuel Yee of UCLA, is published in The Astrophysical Journal Letters. Its title calls the result a disappearing act.

The planet has not gone anywhere. It still circles its star every 8.2 days; Mercury, the planet closest to the Sun, takes 88. What changed is the tilt of its orbit, which no longer carries it across the face of the star as seen from Earth.

A path that crept to the edge

A transit is the small dip in starlight when a planet passes between its star and us. A planet is seen to transit only when its orbit is within a few degrees of edge-on, so a small change in tilt can make transits appear or disappear.

TOI-2535 b is a gas giant with a radius 0.844 times Jupiter's, on an orbit that takes 8.236 days. Its star is an old, early K dwarf, a type of star smaller and cooler than the Sun, about 1,100 light-years away in the constellation Corvus.

TESS observed the star in five sectors, its stretches of watching one patch of sky, between April 2019 and March 2026. In each sector with a transit, the team measured the impact parameter: how far the planet's path passed from the center of the star, in units of the star's radius. Zero means straight through the middle, and larger values mean a path nearer the edge.

That number was about 0.2 in 2019 and 2021, about 0.58 in 2023 and about 0.87 in 2025. The team's fit strongly favors a 2019 path on the other side of the star's center from the later ones, so the path swept across the star's face and toward its edge. It moved at 0.16 star radii a year, the fastest rate of tilt change seen for a planet around a single star.

As the path moved outward, each transit grew shorter and shallower, because the planet was crossing a shorter stretch of the star. In the March 2026 data there was no transit to see.

Clues to an unseen neighbor

The transits were not only fading. They were also arriving off schedule, up to 6 hours early or late, while each transit time is measured to within 2 to 3 minutes. A planet on its own keeps time like a clock, so a shift that large points to something else pulling on it.

The team modeled the timing shifts and the changing transit lengths together, along with measurements of the star's wobble, the small back-and-forth tug a planet's gravity gives its star. Their favored explanation is a neighbor planet that does not transit. In that picture, the same pull that tilts TOI-2535 b's orbit also makes its transits come early or late.

Their models show the neighbor is likely of Saturn's mass or more, and in or near a resonance with TOI-2535 b, meaning their orbital periods form a simple ratio. The favored arrangements have the two periods in a 2:1 or 3:2 ratio.

In those models, the orbit slowly turns, a motion called nodal precession, and goes through one full cycle in 30 to 50 years. That is short next to two other systems the paper compares it with, TOI-216 at 150 years and TOI-4504 at 250 years.

What is not settled

No one has seen the neighbor. The current data do not pin down its exact mass or orbit, and several arrangements of the two planets fit. A second giant planet would add its own tug to the star's wobble, so the team says frequent measurements of that wobble are the best way to find it.

The disappearance itself rests on the last TESS sector. The authors call the missing transit a strong indication that the planet no longer crosses its star; the 2026 path was not measured.

Why it matters

The result shows that a planet's transits can come and go within a few years, because a small change in the tilt of its orbit is enough. The authors call the changing transit lengths one of the most extreme examples of planets reshaping each other's orbits on human timescales. If the neighbor is confirmed, the system would hold two giant planets on tight orbits, which the authors call unusual.

So the planet has not vanished. In the team's picture, the pull of an unseen neighbor has tilted its orbit out of line with Earth. In their models that tilt rocks back and forth, cycling once in 30 to 50 years, so we would expect the path to swing back across the star at some point in that cycle.