#BLUE CLOUD ON #MARS: Mars is supposed to be red. But when amateur astronomer #ThomasWilliamson looked on Oct. 26th, he saw a different color. "The north pole was electric blue," he says.

Williamson photographed the North Polar Hood, a giant cloud of water ice that forms over the Martian north pole during winter. Why blue? That's the color of sunlight scattered from very tiny crystals of ice (smaller than the wavelength of light itself) floating in the cloud.

"Mars was amazing through my binoviewers on my 12.5-inch f/5.1 Newtonian at about 400x!" says Williamson. "I'm looking forward to the next few weeks as Mars increases in apparent size."

Indeed, the view is about to improve. Mars is approaching Earth for a close encounter on Dec. 1, 2022. Between now and then, Mars will double in brightness to magnitude -1.9 (brighter than Sirius) and increase in size to 17.2 arcseconds. Look for the Red Planet and its blue hood rising in the east after sunset in the constellation #Taurus