James Webb Unveils the Coldest Exoplanet Ever Discovered—Orbiting the Ghost of a Dead Star

Getting to see our solar system in the bigger picture of the galaxy doesn’t happen often. It’s pretty cool when you think about how small our little corner of space really is compared to everything else out there. Most of the time we’re just focused on our own planets and sun, so stepping back to see where we fit in the grand scheme of things is kind of mind-blowing.

So astronomers using the James Webb Space Telescope just spotted something wild — a planet orbiting a dead star. It’s the first time we’ve seen something like this, and it’s giving us new clues about what happens to planets when their host star reaches the end of its life.

The planet, called WD 1856+534 b, is also officially the coldest exoplanet we’ve found so far. That’s a big deal because studying its atmosphere could help us understand gas giants better, not just out there in space but even in our own solar system.

Mary Anne Limbach, who led the study, said the team was pretty shocked when they realized what they were looking at. “We were all a little surprised — and pumped — to confirm it was actually a planet, and a super cold one at that,” she told Space.com. It’s one of those discoveries that makes you realize space still has plenty of surprises left.

So there’s this planet called WD 1856+534 b – it’s about the size of Jupiter and hangs out roughly 80 light-years away from us. Scientists first spotted it back in 2020, and it’s got this crazy tight orbit around a white dwarf, basically the leftover core of a star like our sun, zipping around it every day and a half. At first, researchers couldn’t tell if it was actually a planet or one of those brown dwarfs that never quite made it as proper stars. They only had some rough temperature readings from the old Spitzer telescope to go on.

But now the James Webb Space Telescope has given them way better data, letting them actually see the planet’s light and figure out how heavy and hot it really is.

So turns out WD 1856+534 b is definitely a planet. The crazy part is this thing somehow survived what they call the “forbidden zone” around its star. That’s the area so close to a white dwarf that any planet there should’ve gotten wrecked when the star blew up and expanded way bigger before shrinking back down to its current tiny size.

One of the researchers, Limbach, said this basically proves planets can make it through their star’s violent death and end up in places we never thought they could. It’s not just about updating our planet evolution theories either – this could mean planets might actually move into the sweet spot around white dwarfs where life could potentially exist.

Limbach put it pretty well – it’s wild to finally have real proof this whole process actually happens out there. First time we’ve seen it for real.

Man, WD 1856+534 b is seriously freezing out there. We’re talking negative 125 degrees Fahrenheit cold, which makes it the chilliest planet we’ve spotted so far. The old record holder, Epsilon Indi Ab, was practically tropical at 35 degrees in comparison.

The James Webb Space Telescope hasn’t quite hit its full potential yet—it could theoretically pick up planets way colder, like negative 324 degrees. But they’re working on it, and if things go right, we’ll start getting way more details about planets that kinda resemble Jupiter and Saturn.

Limbach put it pretty well—this is a big deal. It’s not every day we get to see how our own solar system stacks up against the rest of the galaxy.

Limbach and her crew are gearing up to take another look at the WD 1856+534 system with JWST this July. They’re basically trying to see if anything’s changed since last time by checking how the system lines up with stars in the background. If they spot another planet hanging around, it might finally explain how WD 1856+534 b wound up so close to its white dwarf star.

But even if they come up empty, the new data will still help astronomers figure out how planets end up in these weirdly tight orbits around white dwarfs. Limbach mentioned it’ll at least help them cross some possibilities off the list. It’s one of those things where you learn something either way, even if it’s not what you expected.

“Either way, it’s a crucial next step in figuring out how these systems evolve.”