Cheops Reveals a Rugby Ball Shaped Exoplanet

European Space Agency’s exoplanet mission Cheops has revealed that an exoplanet orbiting its host star within a day has a deformed shape more like that of a rugby ball than a sphere. The deformation of an exoplanet has been detected, offering new insights into the internal structure of these star-hugging planets.

WASP-103b is located in the constellation of Hercules. It has been deformed by the strong tidal forces between the planet and its host star WASP-103, which is about 200 degrees hotter and 1.7 times larger than the sun. They experience tides in the oceans of Earth mainly due to the Moon tugging slightly on our planet as it orbits us.

The sun also has a small but significant effect on tides, however it is too far from Earth to cause major deformations of our planet. WASP-103b, a planet almost twice the size of Jupiter with 1.5 times its mass, orbiting its host star in less than a day. Astronomers have suspected that such a close proximity would cause monumental tides, but up until now they haven’t been able to measure them.Using new data from ESA’s Cheops space telescope, combined with data that had already been obtained by the NASA/ESA Hubble Space Telescope and NASA’s Spitzer Space Telescope, astronomers have now been able to detect how tidal forces deform exoplanet WASP-103b from a usual sphere into a rugby ball shape.

Cheops measures exoplanet transits—the dip in light caused when a planet passes in front of its star from our point of view. Ordinarily, studying the shape of the light curve will reveal details about the planet such as its size. The high precision of Cheops together with its pointing flexibility, which enables the satellite to return to a target and to observe multiple transits, has allowed astronomers to detect the minute signal of the tidal deformation of WASP-103b. This distinct signature can be used to unveil even more about the planet.