"The cradle of life does not necessarily require a sun."

The Hydrogen-rich exomoon atmospheres could hold liquid water for billions of years.

A moon lost in interstellar darkness may still be able to hold on to liquid water, no star required. A modeling study suggests that some exomoons orbiting rogue planets could stay warm for billions of years, even after their host worlds are thrown out of their star systems and into the cold of deep space.

The finding challenges the familiar idea that potentially habitable worlds must receive light from a nearby star. Instead, the study points to a different engine for habitability — heat generated inside a moon by tidal stress, then trapped by a thick hydrogen atmosphere.

Rogue planets drift through space without orbiting a star. Astronomers think many of them were thrown out of their original planetary systems during violent gravitational encounters.

When a giant planet gets ejected, the orbits of its moons can become stretched into more elongated shapes. As the moon moves closer to and farther from its host planet, the planet’s gravity repeatedly squeezes and flexes the moon’s interior.

That process, called tidal heating, can generate a steady supply of internal heat. Jupiter’s moon Io offers a familiar example: tidal forces make it the most volcanically active body in the solar system. Europa and Enceladus also show how internal heat can keep water-rich worlds active far from the sun.

Earlier studies had already suggested that rogue-planet moons might stay warm enough for liquid water if they built up thick carbon dioxide atmospheres.

But those models ran into a serious problem. In the deep cold expected around free-floating planets, carbon dioxide can condense out of the air. Once that happens, the atmosphere can collapse, and much of the moon’s heat escapes into space.

The new study tackles that problem by swapping carbon dioxide for hydrogen. Hydrogen is the lightest element, and in Earth’s thin atmosphere it does very little to trap heat.

Under very high pressure, though, hydrogen behaves differently. When hydrogen molecules crowd together and collide, they briefly form pairs and clusters that can absorb infrared radiation.

Scientists call this process collision-induced absorption. In plain terms, a dense hydrogen atmosphere can act like a surprisingly strong heat blanket.

Hey all, I've been looking at some photos that NASA has been releasing (like ones from Discover) and noticing a lot of the cameras on probes/sats they use a triple overlay to creature fully colored (to us) images.

Why is using three separate pictures so common? Is it because it's easier/takes less time to get one wavelength of light at a time?

See the videos here. I apologies for using Imgur, sincerely.

This rocket is a Falcon-9 carrying the Cargo Dragon spacecraft C211 (its fourth flight). It's carrying more than 6,300 pounds of science equipment and supplies to the International Space Station, and should arrive there Thursday after a roughly 52-hour flight.

A leopard-spotted rock that could prove whether life ever existed beyond Earth is sitting in a tube on Mars.

NASA’s Perseverance rover grabbed up the sample, called Sapphire Canyon, from rocky outcrops on the edges of the Neretva Vallis, a valley sculpted by rivers that once flowed into an ancient lake in Jezero Crater more than 3 billion years ago.

The rover landed at the dried lakebed in February 2021 for expressly this purpose, hunting for rocks created or modified by water in the past, which would have had the best chance of preserving evidence of life.

Members of the Perseverance science team have said the Sapphire Canyon sample, about the size of a chalk stick, is exactly the type of rock they hoped the rover would discover.

“This is the first time I think we’ve found something that qualifies as a ‘potential biosignature’” on Mars, said Adrian Broz, a member of Perseverance’s science team and a postdoctoral researcher in the Planetary Surface Processes Lab at Purdue University in Indiana.

“It’s currently sealed inside of Perseverance rover’s chassis, and it sits there quietly and awaits return to Earth.”

But the sample might not make it to our planet, at least not anytime soon.

The Mars Sample Return program, a joint venture by NASA and the European Space Agency to ferry the promising cache back to Earth, attracted intense scrutiny for its high price tag and complex design.

After sinking billions of dollars into the endeavor, NASA paused and began reassessing the program in 2024 before canceling it entirely — with no clear alternative in sight.

“While Perseverance’s samples remain safely stored on Mars, NASA is exploring a range of potential return options that could offer simpler and more affordable approaches than the original Mars Sample Return plan, including possible commercial or international contributions,” the agency said in a statement shared with CNN in July.

NASA’s leaders still haven’t revealed a path forward. And while the discovery of the Sapphire Canyon sample is building a strong case for the existence of ancient microbial life on Mars, there’s only so much scientists can learn from afar, said Dr. Briony Horgan, professor of Earth, atmospheric and planetary sciences at Purdue University.

The rover, which cost NASA about $2.4 billion to build and launch, doesn’t have the instrument suite to answer such lofty questions by itself on the red planet.

Moonlight reflected off the Amazon river. At the proper angles in our orbit, we aboard ISS can see brief silvery flashes atop water surfaces, illuminating even the darkest places on Earth. I took this photo with Nikon Z9 camera on Expedition 72, during a nighttime pass over South America. More photos like this from space can be seen on my twitter and Instagram, astro_pettit, for those interested

The Geophysical Instruments for Marius Lunar pit Investigation (GIMLI) will investigate a “skylight,” or a hole in an old lunar lava tube, to see if a large cave system extends beyond it. Such a location could provide a safe place for astronauts to operate on the surface in the future.