Astronomers Find Football-Shaped Exoplanet in First Discovery of Its Kind

Astronomers have detected a planet that they say has been deformed by the gravity of its host star, so much so that it's now shaped like an NFL football.

The planet, known as WASP-103b, is located around 1,225 light-years away from Earth in the constellation of Hercules. The planet is huge—a gas giant 1.5 times the size of Jupiter. But unlike Jupiter, the planet orbits extremely close to its host star.

WASP-103b is only 1.8 million miles away from its star WASP-103. By comparison, Earth is on average 93 million miles away from the sun. The planet is so close to its star that it completes an orbit of it in less than a day. It's also very hot, at around 4,000 F.

Yet it's the planet's warped features that have caught the attention of astronomers. As WASP-103b orbits its star it is constantly exposed to huge gravitational tides.

Astronomers had suspected that these tides would be sufficient to bend the shape of planets, but they had not been able to measure the extent to which this might happen—until now.

Using new data from the European Space Agency's Characterising Exoplanets Satellite (CHEOPS) space telescope, as well as existing NASA data, a huge team from several institutions around the world detected that WASP-103b had been warped into a football shape by its star.

According to Susana Barros, lead author of the study and a researcher at the Instituto de Astrofísica e Ciências do Espaço, a Portuguese space science center, it's the first time that scientists have measured the deformation of a planet outside of the solar system.

"Most planets are spherical due to the force of gravity," Barros told Newsweek. "Their vertical axis is sometimes slightly smaller than the equatorial axis due to rotation." In other words, planets are often slightly squashed and fatter in the middle due to their spin.

Others, though, are further warped by the gravity of their stars. "There are only a few planets like this and this one is the one that has the strongest measurable signature," Barros said, noting that there are three more that could be measured in the next two to three years and another 10 that are "probably deformed" but will be difficult to measure currently.

The team detected the shape of WASP-103b by precisely measuring the dip in light from its host star as the planet passes in front of it with respect to Earth. This method is known as transit photometry and is frequently used to detect exoplanets.

Usually this method can reveal things like the planet's size, but the CHEOPS satellite helped the researchers pick out the tiny details necessary to determine the planet's shape as well.

It will take further measurements with CHEOPS, as well as the newly-launched James Webb Space Telescope, to further decipher additional details about the planet such as its internal structure.

An artist's impression of exoplanet WASP-103b. The planet is thought to be shaped like an NFL football or rugby ball. S. Poletti/ESA