See Comet ATLAS Scoot Across Orion This Week

Comet ATLAS is the green, fuzzy blob to the right of Orion's Belt. I took this photo on Nov. 9 with a 200mm lens set to f/2.8 and a time exposure of 40 seconds at ISO 800 on a tracking mount. The nebula NGC 2024 at left is part of a star-forming region in Orion. Bob King

Comet NEOWISE was the last bright comet easily visible from the northern hemisphere. Not that we're found a replacement for that incredible sight, but Comet ATLAS (C/2020 M3) is doing its best this month to fulfill that role. Currently the brightest comet in the sky, it's located in Orion the hunter and easy to find. 

Comet ATLAS tracks north across Orion this week and next. This map shows its position nightly from Nov. 11-16 around 11 p.m. CDT. Stars are shown to magnitude 8. Stellarium with additions by the author

It glows at 8th magnitude this month, and while not visible with the naked eye, you can see it in a pair of 50mm or larger binoculars as a faint smudge under a dark sky. A 6-inch or larger telescope will give the best view. I've observed the comet a few times through my 15-inch and 10-inch scopes, and it looks like a big, soft patch of light about one-third the apparent diameter of the full moon. While the comet glows a little brighter in the middle, no tail is visible. 

ATLAS tracks across Orion this week and next and moves quickly enough that its motion is easily visible in a telescope in under an hour. In other words, if you find it at 10 p.m. and return at 11 you'll see that it's moved, which is pretty cool. While Orion comes up around 9 p.m. local time it's best to wait until 10 or later to seek Comet ATLAS when it's higher up in the sky.  It culminates — reaches its greatest altitude — around 2 in the morning in mid-November.

Master astrophotographer Michael Jaeger of Austria took this beautiful portrait of the Orion Nebula and Comet ATLAS on Nov. 7. ATLAS glows green from carbon-rich gas excited by ultraviolet (UV) light from the sun. Michael Jaeger

The all caps name stands for Asteroid Terrestrial-impact Last Alert System or ATLAS. ATLAS consists of two telescopes, 100 miles (161 km) apart, which automatically scan the entire sky several times a night looking for moving objects or the appearance of never-before-seen "stars" like supernovae. To date, the project has discovered 53 comets, 57 potentially hazardous asteroids and over 7,000 supernovae. It spotted Comet ATLAS on June 27th this year when the comet was still extremely faint.

Now it's at peak brightness and will pass closest to the Earth at a distance of 33.3 million miles (53.6 million km) on Nov. 14. That's plenty far away to not be a threat but close enough go out on a dark, clear night and make the comet's acquaintance. Good luck!

Join the party!

On another note, I want to let you know that this week the Bell Museum in St. Paul, Minn. is hosting the Virtual Statewide Star Party 2020. The free event takes place all week with talks, stories and live telescope observation. I'll be speaking at 7 p.m. Friday the 13th about the best sky events visible through the end of the year. Click the link and register — see you there!


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