Astronomers just weighed a rogue planet 10,000 light-years away
Astronomers have, for the first time, measured the mass of a "rogue planet"—one that's not orbiting any star.
This Saturn-sized wanderer sits about 10,000 light-years from Earth.
The breakthrough came thanks to a cosmic trick called microlensing, where the planet's gravity bends and brightens the light from a distant background star.
How did they pull it off?
Researchers used both ground telescopes and ESA's Gaia spacecraft (sitting 1.5 million km away) to watch as the rogue planet passed in front of another star.
The event caused sudden brightness spikes—lasting just hours—which let scientists calculate its mass by comparing what each telescope saw.
Why does this matter?
This is the first time anyone has directly measured how much one of these free-floating planets weighs without guessing its distance.
It opens up new ways to study how such planets form and drift through space.
And with NASA's Roman Space Telescope launching in 2027 (with a field of view 100x bigger than Hubble), we're likely to spot hundreds more wandering worlds soon.