Subterms
Small worlds around other stars may come in more than two varieties. Using exoplanet densities, astronomers have largely sorted planets that are bigger than Earth but smaller than Neptune into two categories: denser, rocky super-Earths and larger, puffy mini-Neptunes (SN: 6/19/17). Mini-Neptunes are generally thought to be padded in thick layers of hydrogen and helium […] More
Newly christened “Dimorphos” is a tiny space rock with a big target on its back. The International Astronomical Union gave the rock an official name on June 23 for a unique reason: It has been marked for the first-ever asteroid deflection mission. A NASA spacecraft will ram into Dimorphos — on purpose — to alter […] More
Geoffrey Evatt was snowmobiling in Antarctica when he spotted an outlandish feature. A black rock stood so starkly against the diamantine ice that even the untrained eye would have known it was not from this world, but a meteorite. “You’ll never get over that high of finding the first one,” he says. Not that it […] More
Microbes can live and grow in an atmosphere of pure hydrogen, lab experiments show. The finding could widen the range of environments where astronomers seek signs of alien life. “We’re trying to expand people’s view of what should be considered a habitable planet,” says exoplanet astronomer Sara Seager of MIT (SN: 10/4/19). “It seems to […] More
In the most comprehensive lunar map yet, the moon looks like it’s been playing paintball. Each splash of color identifies a discrete rock or sediment formation, including craters, basins and ancient lava fields. For instance, “the darker, more earth tones are these highland-type terrains, and the reds and the purples tend to be more of […] More
A new look at the nitrogen on Venus may overturn a decades-old assumption about the planet’s atmosphere. Scientists long thought that atmospheric turbulence would create a uniform mixture of gases in Venus’s atmosphere below an altitude of about 100 kilometers. That’s how it works on Earth. But data from NASA’s MESSENGER spacecraft now indicate that […] More
A suspected subsurface ocean on Pluto might be old and deep. New analyses of images from NASA’s New Horizons spacecraft suggest that the dwarf planet has had an underground ocean since shortly after Pluto formed 4.5 billion years ago, and that the ocean may surround and interact with the rocky core. If so, oceans could […] More
The asteroid Ryugu is light and fluffy. Images taken by Japan’s Hayabusa2 spacecraft suggest the whole asteroid is highly porous, scientists report in Nature on March 16. “It is something like freeze-dry coffee,” says planetary scientist Tatsuaki Okada of the Japanese Aerospace Exploration Agency. If early protoplanets had similar structures, that could mean planets formed […] More
