Astro Blog

By Daniel Clery , Science.  Excerpt: Staring deep into space and far back in time, a team of astronomers may have spotted a galaxy full of stars made from only the primordial gas created in the Big Bang. Such “population III stars” would have formed from hydrogen and helium and nothing else, and researchers have been searching for them for decades.... If confirmed, the discovery, made with NASA’s JWST space observatory, opens a window on the starting point of the chemical enrichment of the universe, in which the heavier elements needed to make planets and life began to be forged in stellar explosions. ...The nature of population III stars remains uncertain. Most theorists think they were huge, with masses up to 1000 times that of the Sun, 10 times larger than any star around today. ...The gigantic stars that resulted would also burn hot and fast, ending in a supernova explosion after just a few million years. That brief first flash of population III stars is hard for astronomers to...

By Robert Sanders , UC Berkeley News.  Excerpt: Mars today is a cold, dry, dusty planet with its only obvious water locked up in frozen polar ice caps. But billions of years ago, it appears to have had sandy beaches lapped by waves along the shoreline of a vast ocean. The evidence for beaches on Mars comes from a Chinese rover, called Zhurong, that landed on the planet in 2021. During its short life it detected evidence of underground beach deposits in an area thought to have once been the site of an ancient sea, bolstering the idea that the planet long ago had large bodies of water. ...between May 2021 and May 2022, Zhurong traveled 1.9 kilometers (1.2 miles) roughly perpendicular to escarpments thought to be an ancient shoreline from a time — 4 billion years ago — when Mars had a thicker atmosphere and a warmer climate. Along its path, the rover used ground penetrating radar (GPR) to probe up to 80 meters (260 feet) beneath the surface. ...“The structures don’t look like sand du...

By Sarah Stanley , Eos/AGU.  Excerpt: A closer look at previously disregarded observations reveals stronger evidence that a deep ocean lies beneath Callisto’s icy surface. ... Cochrane et al.  have revisited the Galileo data in more detail. Unlike in prior studies, this team incorporated all available magnetic measurements from Galileo’s eight close flybys of Callisto. Their expanded analysis much more strongly suggests that Callisto hosts a subsurface ocean....  Full article at https://eos.org/research-spotlights/jupiters-moon-callisto-is-very-likely-an-ocean-world . 

By Lan Dai  and  Axel Timmermann , ScienceAdvances.  Abstract summary: Asteroid Bennu has a 0.037% chance of colliding with Earth in 2182 CE.  The potential collision of such medium-sized asteroids would inject dust into the atmosphere and disrupting climate, vegetation, and marine productivity. Simulations show global temperature drop of 4°C, reduced precipitation, and significant decreases in terrestrial and marine net primary productivity....  Full article at https://www.science.org/doi/10.1126/sciadv.adq5399 .  See also Life’s Building Blocks Found in Bennu Samples (Eos/AGU)

By Center for NEO Studies (CNEOS), JPL/CalTech.  Excerpt: CNEOS analysis of near-Earth asteroid 2024 YR4, which is estimated to be about 40 to 90 meters wide, indicates it has a more than 1% chance of impacting Earth on Dec. 22, 2032 — which also means there is almost a 99% chance this asteroid will not impact. These analyses will change from day to day as more observations are gathered. The CNEOS analyses are used for NASA’s contribution to the  International Asteroid Warning Network (IAWN) . After the impact probability for this asteroid reached 1%, IAWN issued its official  notification  for the potential impact....  Full article at https://cneos.jpl.nasa.gov/news/news210.html .  See also: International Asteroid Warning Network - https://iawn.net/obscamp/2024YR4/index.shtml , explanation of the Torino Scale on Wikipedia - https://en.wikipedia.org/wiki/Torino_scale , European Space Agency Near-Earth Objects Coordination Center - https://neo.ssa.esa.int/-...

By Daniel P. Glavin et al, Nature Astronomy.  Abstract Excerpt: Organic matter in meteorites reveals clues about early Solar System chemistry and the origin of molecules important to life.... Samples returned from the B-type asteroid Bennu by the Origins, Spectral Interpretation, Resource Identification, and Security–Regolith Explorer mission ...show that Bennu samples are volatile rich, with more carbon, nitrogen and ammonia than samples from asteroid Ryugu and most meteorites. ...Bennu’s parent asteroid developed in or accreted ices from a reservoir in the outer Solar System where ammonia ice was stable. ...The transport and delivery of organic compounds from these bodies could have been a source of molecules available for the emergence of life on Earth and potentially elsewhere....  Full article at https://www.nature.com/articles/s41550-024-02472-9 .  See also Nature article An evaporite sequence from ancient brine recorded in Bennu samples [Brines ...are environment...