Comet 2I/Borisov, the solar system’s second known interstellar visitor, probably hails from a planetary family that is chemically distinct from our own. During Borisov’s brief sojourn through the inner solar system, it was enveloped in its own tenuous gas cloud created as the sun baked ice on the comet’s surface (SN: 10/14/19). New observations 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
SpacefarersChristopher WanjekHarvard Univ., $29.95 By 20th century expectations, we are way behind schedule on colonizing the solar system. After the Apollo moon landings, some scientists and NASA officials envisioned launching astronauts to Mars in the 1980s and building cities in space to be habitable by the 2000s. But the only humans in space today are […] More
Saturn’s auroras may heat its atmosphere like an electric toaster. Measurements from NASA’s Cassini spacecraft’s final orbits show that Saturn’s upper atmosphere is hottest where its auroras shine, a finding that could help solve a long-standing mystery about the outer planets. Saturn’s upper atmosphere is much hotter than scientists first expected based on the planet’s […] 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
A joint European and Russian mission to Mars is being postponed from July until sometime in 2022, as the coronavirus pandemic is preventing scientists from resolving a few technical difficulties, the European Space Agency said March 12. “We cannot fly in 2020,” ESA director general Jan Wörner says. “This is a disappointment for me personally, […] More
On one distant world, “heavy metal” could be a weather forecast. Telescope observations indicate that an exoplanet nearly 400 light-years away has iron rain. The planet, dubbed WASP 76b, is an extreme kind of exoplanet known as an ultrahot gas giant (SN: 7/30/19). These worlds “are complete oddballs,” says astronomer David Ehrenreich of the University […] More
