Astronomers Baffled by Exoplanet with Dramatically Tilted Orbit

Explore the mystery of TOI-3884, an exoplanet with a severely tilted orbit. With no clear cause for its 62-degree tilt, this discovery challenges planetary science.

Astronomers have discovered a planet whose orbit is dramatically tilted compared to the spin of its star, and no one yet knows why. The system, called TOI-3884, shows a strange mismatch between the direction the star rotates and the way the planet travels around it. Such extreme tilts are usually blamed on past run-ins with giant planets or companion stars, but none appear to be present here which makes this discovery particularly puzzling.

Planet TOI-3884 Discovered

To understand what was happening, researchers first studied moments when the planet crossed in front of dark patches on the star’s surface. These patches, known as starspots, are similar to sunspots on our own Sun: cooler, darker regions caused by magnetic activity. The team used special multicolour instruments called MuSCAT3 and MuSCAT4, which are attached to two of the Las Cumbres Observatory’s 2-metre telescopes. Over February and March 2024, they captured three separate transits, moments when the planet passed in front of the star, and clearly saw the tiny dips in light caused by the planet sweeping over the starspots.

By studying how the signals changed in different colours of light, the scientists were able to estimate the temperature and size of these starspots. Their analysis showed the spots are about 200 Kelvin cooler than the rest of the star’s surface, which sits at roughly 3150 Kelvin. The spots cover around 15 per cent of the visible surface. They also noticed small changes in the shape of the spot-crossing signals between the three transits. Because these changes happened over only a few weeks, the team concluded they were caused by the star rotating, not by the starspots themselves shifting or fading.

Strange Exoplanet System

To confirm this, the researchers monitored the star’s brightness over several months using Las Cumbres Observatory’s worldwide network of 1-metre telescopes. From December 2024 to March 2025, they took repeated measurements each night and found consistent, repeating variations, a clear sign of stellar rotation. These observations allowed them to calculate that the star completes one full spin every 11.05 days.

When they combined this rotation period with the earlier transit data, the team could map out the 3-D structure of the system. They discovered that the star’s spin axis and the planet’s orbital axis differ by about 62 degrees. In other words, the planet’s orbit is strongly tilted relative to the star’s rotation, far more than astronomers usually expect.

Because no massive neighbouring planets or companion stars have been found, there is no obvious explanation for this dramatic tilt. As a result, TOI-3884 is now one of the most intriguing planetary systems known, offering scientists a rare opportunity to explore how unusual orbits form and evolve.