Astro Blog

By Tom Metcalfe , Eos/AGU.  Excerpt: Tiny crystals in Earth’s crust may have recorded meteorite and comet impacts as our planet traveled through the spiral arms of the Milky Way over more than 4 billion years, according to new research. ...The key to the latest research was in the ratios of isotopes—forms of the same chemical element that have different numbers of neutrons—in the oxygen atoms of zircon’s silicate group. The relative levels of oxygen isotopes in samples of zircon crystals can tell geologists whether the crystals formed high in the crust, perhaps while interacting with water and sediments, or deeper within Earth’s mantle. ...The scientists evaluated the data’s “ kurtosis ,” or the measure of how flat or peaked a distribution is. ...The researchers determined that periods of high oxygen isotope kurtosis corresponded to times when our solar system was crossing the dense spiral arms of the Milky Way galaxy. Such crossings occurred roughly every 187 million years on aver...

By Javier Barbuzano , Eos/AGU.  Excerpt: Almost a decade after NASA’s InSight mission put the first working seismometer on the Martian surface, ...scientists reported seismic evidence that Mars has a solid inner core, an unexpected finding that challenges earlier studies that suggested the planet’s core was entirely molten. ...the interior of Mars has layers... [with] different densities and can be solid or liquid. As seismic waves move through the layers, they are bent or reflected, especially at boundaries where density changes sharply. ...Previous analyses of InSight data had already mapped the structure of the Martian  crust  and  mantle  and also revealed that the planet has a surprisingly  large molten metallic core , spanning nearly half its radius. ...the new finding caught InSight scientists off guard....  Full article at https://eos.org/articles/scientists-may-have-finally-detected-a-solid-inner-core-on-mars .  See also Dust devil migrat...

By Victoria Corless , Space.com.  Excerpt: Scientists have identified a lone planet with a ferocious appetite. Located in the Chamaeleon constellation roughly 620 light-years away, the rogue planet, named Cha 1107-7626, exists in the vast emptiness of space, far from the warmth of any star. ...Using the  European Southern Observatory 's (ESO)  Very Large Telescope  (VLT), astronomers have caught it pulling in gas and dust at an astonishing rate: six billion tons every single second. Never before has a rogue planet, or any planet, been observed growing this fast. "This is the strongest accretion episode ever recorded for a planetary-mass object," Almendros-Abad said. With a mass equivalent to between five and 10 Jupiters, Cha 1107-7626 is one of the lowest-mass free-floating planets known to host a disk and show active accretion. Observations from ESO's VLT and NASA's  James Webb Space Telescope  (JWST) reveal telltale signs of a rich, evolving system ...sil...