In the search for planets beyond our solar system, astronomers have found a giant exoplanet that looks more like a football or rugby ball than a sphere.
The planet, called WASP-103b, is one of extremes. Located about 1225 light-years from Earth in the Hercules constellation, the planet is almost twice the size of Jupiter.
The strange world is also 50 times closer to its star than Earth is to the sun. It completes one full orbit around its star, WASP-103, in just under one Earth day. With its scale and short orbit, this gas giant is categorized a "hot Jupiter" planet.
The planet was first discovered in 2014 and has been observed using the Hubble and Spitzer space telescopes.
Researchers wanted to get another perspective of WASP-103b using CHEOPS, or the joint mission of Switzerland and the European Space Agency's CHaracterising ExOPlanet Satellite, to combine with previous observations.
The satellite, launched in 2019, searches for potentially habitable planets. It detects planets using the transit method, or measuring the dips in stellar brightness when a planet passes in front of a star.
When astronomers observed WASP-103b pass in front of its star, they were able to see the planet's odd, football-like shape.
A study detailing the findings published Tuesday in the journal Astronomy and Astrophysics.
"After observing several such so-called 'transits,' we were able to measure the deformation. It's incredible that we were able to do this - it's the first time such an analysis has been done," said study co-author Babatunde Akinsanmi, a postdoctoral researcher at the University of Geneva, in a statement.
The role of ocean tides
The researchers suspect the elongated shape is due to the force of massive tides occurring on the planet.
On Earth, ocean tides are largely the result of the gravitational pull of the moon. This force causes low and high tides, but nothing dramatic enough to be visible from space.
"Because of its great proximity to its star, we had already suspected that very large tides are caused on the planet. But, we had not yet been able to verify this," said study co-author Yann Alibert, a professor of astrophysics at the University of Bern, in a statement.
The deformation of the planet also allowed researchers to learn more about its composition, which is gaseous like Jupiter. While the largest planet in our solar system has a frigid average temperature of -108C, this planet is likely inflated due to heat from its incredibly close star, which is why it is considered to be a "hot Jupiter" planet. The star is about 200 degrees hotter and 1.7 times larger than our sun.
Astronomers want to probe another mystery about the planet. Typically, a massive planet like this closely orbiting its host star would gradually get closer to the star over time and become engulfed by it. Current measurements seem to suggest that the planet is drifting further away, rather than closer in to its star.
Future observations can help astronomers uncover more about the planet's internal structure and deformation, as well as any similar exoplanets. Hot Jupiters proved to be common during the early days of exoplanet detection, but deformed planets are incredibly rare.
Previously, the Hubble Space Telescope revealed that the extreme heat and intense gravity of its star is warping another planet, called WASP-121b, into the shape of a football.
"This would improve our understanding of these so-called 'hot Jupiters' and allow a better comparison between them and giant planets in the Solar System," said study co-author Monika Lendl, an assistant professor of astronomy at the University of Geneva, in a statement.
