Astro Blog

https://eos.org/articles/zhurong-rover-spots-evidence-of-recent-liquid-water-on-mars ]  By Katherine Kornei , Eos/AGU.  Excerpt: Mars is hardly a verdant world today, yet evidence abounds that liquid water  once flowed over the Red Planet . Now, the latest rover to arrive on Mars’s surface—Zhurong, part of China’s  Tianwen-1 mission —has spotted hydrated minerals that point to liquid water persisting well into the Red Planet’s most recent geologic period. These results,  published in  Science Advances , contribute to our understanding of when liquid water flowed on Mars, the research team has suggested.…

https://eos.org/articles/why-did-sunspots-disappear-for-70-years-nearby-star-holds-clues By Kimberly M. S. Cartier , Eos/AGU. Excerpt: Every 11 years, the number of spots dotting the surface of the Sun increases and decreases like clockwork. Astronomers have been tracking the 11-year sunspot cycle for more than 400 years, using it to better understand the chaotic magnetic field the Sun puts out. (The current solar cycle, number 25, started in 2019.) The timing of the solar cycle is remarkably consistent: Sunspot numbers rise and fall, rise and fall…except for that time that they disappeared and weren’t seen again for 70 years. That period of time, from 1645 to 1715, is known as the  Maunder Minimum , named after 19th century British astronomers Edward and Annie Maunder. Astronomers still don’t understand why the Sun ceased making sunspots for 70 years, but a new analysis of more than 5 decades of measurements of nearby stars has identified one that might be undergoing its own Maunder-l

https://news.berkeley.edu/2022/06/10/astronomers-may-have-detected-a-dark-free-floating-black-hole/ By Robert Sanders , UC Berkeley News.  Excerpt: If, as astronomers believe, the death of large stars leave behind black holes, there should be hundreds of millions of them scattered throughout the Milky Way galaxy. The problem is, isolated black holes are invisible. Now, a team led by University of California, Berkeley, astronomers has for the first time discovered what may be a free-floating black hole by observing the brightening of a more distant star as its light was distorted by the object’s strong gravitational field — so-called gravitational microlensing. The team, led by graduate student Casey Lam and  Jessica Lu , a UC Berkeley associate professor of astronomy, estimates that the mass of the invisible compact object is between 1.6 and 4.4 times that of the sun. Because astronomers think that the leftover remnant of a dead star must be heavier than 2.2 solar masses in order to co