Astronomy November 2021

Follow the Dave’s Universe blog: www.Astronomy.com/davesuniverse Follow Dave Eicher on Twitter: @deicherstar Fifty years ago, Mariner 9 made history. Launched May 30, 1971, the NASA-made probe entered an orbit around Mars on Nov. 14 of that year — the first craft to orbit another planet. Mariner 9 barely beat a pair of Soviet spacecraft, Mars 2 and Mars 3, to the punch, the latter arriving at the Red Planet a few weeks later. So the space race carried on. We have now spent 50 years on Mars. Mariner 9 opened our eyes, finding the martian atmosphere thick and dusty, the planet’s surface heavily obscured. Eventually, the probe returned more than 7,300 images covering 85 percent of the planet’s surface. A strange new world emerged, with riverbeds, huge volcanoes, canyon systems, and abundant…

We welcome your comments at Astronomy Letters, P.O. Box 1612, Waukesha, WI 53187; or email to letters@astronomy.com. Please include your name, city, state, and country. Letters may be edited for space and clarity. News note Evidence is presented in a report published in the Journal of the Association of Lunar & Planetary Observers (Summer 2020) that a comet consisting of large amounts of ice probably impacted Mars on Sept. 2, 1973. Four members of the McDonnell Douglas Amateur Astronomers Club observed the aftermath of the proposed comet impact, and provided three items of evidence. These include telescopic observations of white clouds that would have happened after the impact, shock waves that lifted airborne dust over a region, and six new craters. — Jim Melka, assistant Mars coordinator of the Association of Lunar…

The virtual, globe-spanning Event Horizon Telescope (EHT) recently zoomed in on the black hole at the center of Centaurus A. Shown here in a false-color composite image that combines optical (blue), X-ray (purple), and infrared (red) light, Centaurus A sits 12 million light-years from Earth. EHT’s new radio image (inset) shows the galaxy’s supermassive black hole (indicated with an arrow) shooting out jets of material. It’s the most detailed view of this region to date, showing features less than 1 light-day across. One jet, whose edges glow as two bright streaks split by a dark void at the upper left of the black hole, is moving toward Earth. The second jet, which has much fainter edges and appears to the black hole’s lower right, is pointing away from us. Astronomers…

STACCATO SUPERNOVA Astronomers have discovered the shortest gamma-ray burst from a supernova — GRB 200826A — which lasted just 0.6 seconds, calling into question researchers’ current understanding of these bursts. MARTIAN LIGHTS The United Arab Emirates’ Hope spacecraft captured detailed images of aurorae on Mars’ nightside (right). The Red Planet has no global magnetic field, so scientists think these aurorae instead trace magnetized rocks in the crust. MILLIMETER MOUNTAINS According to new research, a neutron star’s self-gravity squashes any surface deformations to fractions of a millimeter high — even smaller than the centimetersized ranges suggested in previous work. X-RAY: NASA/CXC/SAO; OPTICAL: ROLF OLSEN; INFRARED: NASA/JPL-CALTECH. INSET: M. JANSSEN ET AL./NATURE ASTRONOMY 2021. BOTTOM FROM LEFT: INTERNATIONAL GEMINI OBSERVATORY/NOIRLAB/NSF/AURA/J. DA SILVA, IMAGE PROCESSING: M. ZAMANI (NSF’S NOIRLAB); EMIRATES MARS MISSION; ESO/L.CALÇADA.…

The new space race isn’t between global superpowers — it’s being hashed out by some of the world’s richest billionaires. Richard Branson and Jeff Bezos are the owners of the commercial space operators Virgin Galactic and Blue Origin, respectively. And in July, both men, alongside their crews, successfully launched themselves into space, ushering in a new era for private spaceflight. BRANSON TAKES FLIGHT Branson flew first on July 11 after Virgin Galactic moved his flight forward, beating Amazon founder Bezos to space by a little over a week. The flight was Virgin Galactic’s first to carry a full crew: In addition to its two pilots, four mission specialists — one of whom was Branson — were charged with evaluating the safety of the flight and the overall astronaut experience. On the morning of…

BACK IN BUSINESS The Hubble Space Telescope suffered a computer memory error June 13 that put the observatory into safe mode. Following weeks of tests, NASA found the issue was a failed power supply. After switching to a backup system, Hubble resumed operations July 17. SHIVERING MOON Icequakes may be constantly rippling across the frozen surface of Saturn’s moon Enceladus, caused by tides in the world’s subsurface water ocean. The suggestion comes from models of Antarctic ice shelves, which float atop coastal waters and tend to fracture during falling tides. SEASONAL RAYS The magnetar SGR1935+2154 — a highly magnetic, fast-spinning neutron star — fires random bursts of low-energy gamma rays for four months, then goes dormant for three months. This behavior was noticed by researchers last year and repeated as predicted beginning in late June. EXTRA…