This strange exoplanet is shaped like a rugby ball

Exoplanets come in many sizes, and sometimes they also have unusual shapes. The European Space Agency’s CHEOPS exoplanet-hunting telescope has discovered a planet shaped like a rugby ball, pulled into that shape by extreme gravitational forces.

The planet, named WASP-103b and located in the constellation of Hercules, experiences epic tidal forces due to its orbit so close to its star, with a year lasting only one day. The planet is large, twice the size of Jupiter, and one and a half times its mass. “Because of its close proximity to its star, we had already suspected that very large tides were occurring on the planet. But, we had not yet been able to verify it”, explained the co-author of the study Yann Alibert, professor of astrophysics at the University of Bern, in a declaration.

Using CHEOPS, the team was able to verify the planet’s tidal warping by examining its transits. When the planet passes between its star and Earth, in an event called a transit, the team could measure the star’s dip in brightness and learn more about the planet. “After observing several of these so-called ‘transits’, we were able to measure the deformation. It’s amazing that we were able to do this – it’s the first time such an analysis has been done,” said co-author Babatunde Akinsanmi.

In addition to measuring its odd shape, the researchers were also able to learn more about the planet’s interior by seeing how it was warped. “A material’s resistance to deformation depends on its composition,” Akinsanmi explained. “We can only see the tides on Earth in the oceans. The rocky part doesn’t move much. Therefore, by measuring how distorted the planet is, we can determine how much of it is made up of rock, gas, or water.

The results suggest the planet is internally similar to Jupiter, despite being twice the size. The researchers therefore believe that the planet has been inflated, perhaps due to the heating of the neighboring star.

The research is published in the journal Astronomy & Astrophysics.