A distant dusty doughnut
Active galactic nuclei, such as the one shown in this graphic, are the luminous centres of some galaxies, and are thought to be powered by supermassive black holes. Researchers reported this week that they had captured a sharp image of a nearby active galactic nucleus, showing a glowing doughnut-shaped object surrounding the hidden black hole.
Light emitted by most active galactic nuclei has key features that allow the nuclei to be classed as type 1 or type 2 objects. A widely accepted unified model suggests that this distinction arises because the line of sight to type 2 objects is obscured by a dusty torus of matter that feeds the black hole. A News & Views article explains more about how the researchers managed the difficult feat of imaging the dust that hides the black hole.
COVID reinfections on the rise
Since the Omicron variant of SARS-CoV-2 was first detected, the number of people reinfected with the coronavirus has been rising sharply — a trend that was not observed with previous variants. This graph shows how the number of reinfections in England has spiked, using data collected by the UK Health Security Agency. (The agency considers an infection a ‘possible reinfection’ if it took place at least three months after a previous one, but does not confirm that these are separate instances through genetic sequencing of the virus.) Researchers say that the new variant is probably driving the surge because it is able to evade the body’s immune defences.
A year-long drive across Mars
Since landing on Mars one year ago, NASA’s Perseverance rover has travelled more than 3 kilometres across rocky terrain, as this map shows. On 18 February 2021, Perseverance touched down in Jezero Crater, just north of the Martian equator. The mission’s goal is to search for signs of past life. Perseverance has spent the year rolling around the bottom of the crater, and has collected six precious rock samples that — if all goes well — will one day be returned to Earth for study. A News story examines the ups and downs of Perseverance’s first adventurous year.