planetary science

NATIONAL HARBOR, MD. — For the first time, astronomers have taken a direct look at an exoplanet’s insides.

An exoplanet about 800 light-years away is spilling its guts into space, and new observations with the James Webb Space Telescope, or JWST, have let astronomers read the entrails, astronomers report this week at a meeting of the American Astronomical Society.

“If this is true, it’s super cool,” says astronomer Mercedez López-Morales of the Space Telescope Science Institute in Baltimore, who was not involved in the new work. “For the first time you can study directly what the interior of an exoplanet is made of. That’s exciting.” More

Pluto and Charon’s meet-cute may have started with a kiss. New computer simulations of the dwarf planet and its largest moon suggest that the pair got together in a “kiss-and-capture” collision, where the two bodies briefly joined up before settling into their current positions.

“It’s a U-Haul situation,” says planetary scientist Adeene Denton of the Southwest Research Institute in Boulder, Colo., who reports the results January 6 in Nature Geoscience. “They kiss and they say, ‘Yeah, this is it. I want to build a system together with you.’ And then they do.” More

WASHINGTON D.C. — The Perseverance Rover on Mars may have stumbled upon the oldest rocks humans have ever seen and, possibly, evidence of a new setting that ancient Martian organisms could have inhabited, if they ever existed.

“This is really one of the most exciting things that this mission is going to do, is to be looking at rocks that were formed so early in the history of the solar system,” said Caltech geochemist Kenneth Farley during a December 12 news briefing at a meeting of the American Geophysical Union. “Almost the dawn of the solar system.” More

Mars’ moons could be the remains of an ill-starred asteroid that got too close to the Red Planet.

A shredded asteroid origin could help explain mysterious features of the small, odd-shaped moons, scientists suggest in the January issue of Icarus.

Where most moons are big round orbs, Mars’ Phobos and Deimos are small lumpy potatoes.

There are two main ideas for how the moons formed. One is that the moons actually were asteroids that were caught by Mars’s gravity. But that idea doesn’t explain the moons’ circular, stable orbits around Mars’ equator. More

The first samples from the farside of the moon contain signs of surprising volcanic activity near the lunar south pole.

Two separate analyses of lunar rocks brought to Earth by China’s Chang’e-6 spacecraft show the rocks formed from cooling magma relatively recently, about 2.8 billion years ago, according to papers published November 15 in Science and Nature. The measurements may help solve the mystery of why the moon’s farside is so different from its nearside, but also raise new questions about the history of lunar volcanism. More

Some of Uranus’ apparent oddities might be due to bad timing.

In 1986, the Voyager 2 spacecraft flew past the planet, recording mysteries of its magnetic field. Turns out, Uranus may have just been in an unusual state. A solar wind event days before the flyby compressed the giant planet’s magnetosphere, researchers report November 11 in Nature Astronomy. That compression could explain several long-standing puzzles about Uranus and its moons, and could inform planning for future missions (SN: 4/20/22). More

Most of Earth’s meteorites can be linked to just a few collisions within the asteroid belt between Mars and Jupiter, two new studies report, including a particularly cataclysmic impact event around 470 million years ago.

The upside to this discovery, published October 16 in Nature, is that it provides researchers with vital context: By knowing the return address of meteorites, scientists can more easily work out how and where the building blocks of planets came together to create the solar system we see today. The downside is that it may mean researchers have an extremely biased meteorite collection that can tell only a sliver of the story. More

Planetary astronomer Bonnie Buratti remembers exactly where she was the first time she heard that Jupiter’s icy moon Europa might host life.

It was the 1980s, and Buratti was a graduate student at Cornell University studying images of the planet’s moons taken during the Voyager 1 and 2 flybys in 1979. Even in those first low-resolution snapshots, Europa was intriguing.

“It looked like a cracked egg,” she says.

Those cracks — in a snow-covered, icy shell — were probably filled with material that had welled up from below, Buratti and colleagues had shown. That meant there had to be something underneath the ice. More