Rare Saturn-sized rogue planet is first to have its mass measured

Nearly 10,000 light-years away, a planet the size of Saturn floats on its own in empty space. As luck would have it, researchers were able to discover this strange, dark world using both ground-based telescopes and telescopes. Gaia Space Telescopeallowing them to measure the mass of a free-floating or wandering exoplanet for the first time.

Most of the rogue worlds discovered are either more massive than Jupiter or lighter than Neptune, leaving a size gap in the middle that researchers call the “Einstein Desert.” This is usually explained by the idea that worlds lighter than Neptune are relatively easy to eject from pre-existing orbits around stars, while planets more massive than Jupiter do not necessarily form within them. traditional planetary systemsbut can sometimes form like stars in free space.

This makes this newly discovered planet especially rare. It has two names – KMT-2024-BLG-0792 and OGLE-2024-BLG-0516 – because Andrzej Udalski from the University of Warsaw in Poland and his colleagues discovered it independently using two different ground-based telescopes. But what's even more unusual is that they were able to measure its mass to be about one-fifth that of Jupiter.

“What's really cool about this is that it's the first device we have that measures mass, and it was only possible because they got observations of Gaia as well as observations from Earth,” says Gavin Coleman at Queen Mary University of London. Researchers discovered the planet using a technique called gravitational microlensing, which occurs when light from a bright, distant object is deflected by the planet's gravitational pull, creating a sort of halo around the planet. This is where the researchers got lucky: when the microlensing event was spotted from the ground, the Gaia space telescope was pointed in the right direction, so it recorded the event too.

“Mass is the main parameter that determines a planet's classification,” Udalski says, so technically this makes it the first confirmed free-floating rogue planet. “This is the point where we can be confident that the candidate is a real planet, and that free-floating planets do exist,” he says. NASA Rome Nancy Grace Space TelescopeHowever, it is expected to discover much more.

“There should be a lot of them, and they could be critical to our understanding of the formation of planetary systems, since most of them are ejected from planetary systems in the early stages of formation,” says Udalsky. This includes our own solar system, as some studies may suggest. threw away the planet in the first days of its existence.

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