By Rick Nowell
Comet Neowise is bright and easy to see now. I took this photo (above) by Ft. Steele on Tuesday morning (July 14) at 1:30 a.m. On news media they say to go before dawn early, like 4 a.m., but that’s too late in northern locations like here. I’d recommend between midnight when it gets fully dark, until 3:30 a.m. when the northern sky brightens with dawn. Otherwise the faint streak of the comet is difficult to see against the glowing sky.
Binoculars make it brighter and allow you to see the pale-blue ion tail and pale-yellow dust tail, but it’s clearly visible by eye.
Here’s the comet two days later, on Thursday morning at 2 a.m. Looking at the background stars, notice it’s shifted slightly upwards and to the left from the first photo. I’m better prepared now, using a more sensitive 28mm f/1.8 lens. The comet looks a bit brighter, a white nucleus at bottom, with a pale-blue ion-jet going straight up, as well as a wide pale-yellow dust tail curving back. Again, along the bottom right you can see Lakit Mountain with trees silhouetted in the red glow of the lights of Ft. Steele.
Let’s zoom in with a 210mm lens for a little more detail. To take comet photos you’ll need about a 10 to 20 second exposure with a SLR camera on a tripod. (A cell phone would be a challenge.) This 210mm photo was taken on a motorized equatorial tripod so the stars don’t make streaks as the Earth rotates.
Why the name NEOWISE C/2020 F3? The comet was discovered by NASA’s Near-Earth Object Wide-field Infrared Survey Explorer, or NEOWISE, on March 27, 2020.
How big is it? NASA says: “From its infrared signature, we can tell that it is about five kilometres [three miles] across, and by combining the infrared data with visible-light images, we can tell that the comet’s nucleus is covered with sooty, dark particles left over from its formation near the birth of our solar system 4.6 billion years ago,” said Joseph Masiero, NEOWISE deputy principal investigator at NASA’s Jet Propulsion Laboratory in Southern California.
I was looking online for a skychart to show comet location this month, Sky&Telescope has one but I didn’t like their layout. So I made this one up in Cartes du Ciel using data from the minor planet centre.net. In the starmap you can see Ursa Major (the Big Dipper) at upper left. The comet drifts left along the feet of Ursa Major. It should remain visible along the Northern horizon until July 26.
If you get a chance, take 50mm binoculars and try to spot the pale-blue ion tail and pale-yellow dust tail. Otherwise it’s clearly visible by eye.
Rick Nowell,
Physics Lab Tech,
College of the Rockies
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2020-07-19 18:04:53Z
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