HOw to Spot the Comet NEOWISE

July 16, 2020

From Sky & Telescope:

An unexpected celestial newcomer, after falling toward the Sun for more than 3,000 years, is making a lovely appearance in our skies right now. You can see it for yourself very low in the northeast as dawn begins to brighten -- and in the evening after sunset less than a week now -- but you'll need to know exactly where and what to look for, and binoculars will help.

Comet NEOWISE is named for the NASA infrared space telescope that discovered it on March 27th. Officially designated C/2020 F3, it passed just 27.4 million miles from the Sun (inside the orbit of Mercury) on July 3rd and has emerged into view low over the horizon in the early dawn.

It's well positioned for skywatchers at mid-northern latitudes (including most of the United States, Canada, and Europe) for the mornings of July 10th through 14th. The farther north you are, the better. "The comet was easily seen by eye on the morning of July 9th," reports Sean Walker, associate editor for Sky & Telescope. "I could see the curve of the tail without optical aid, about 3° long."

Find the Comet: July 10th to 14th

To spot Comet NEOWISE, first find a location that has a nice open view very low to the northeast. Then be prepared to be outside and searching no later than 1 hour and 50 minutes before your local sunrise time. The eastern sky will already be starting to show the first signs of the coming dawn.

Venus will be shining low and brilliant off to the right, in the east-northeast. In your northeast direction will be one bright star. That's Capella, your starting point.

"Look far to Capella's lower left, by somewhat more that the width of your clenched fist at arm's length," suggests Diana Hannikainen (pronounced HUN-ih-KY-nen), Sky & Telescope's Observing Editor. That's where Comet NEOWISE will be hanging out. Look for a faint, fuzzy little "star" with a fainter, fuzzier little tail extending upward from it.

This tail consists of dust and gas that have been driven off the comet's solid core, or nucleus, by the Sun's heat. Astronomers estimate that the nucleus is about 3 miles across, typical for one of these icy bodies. If you have them, binoculars will show the comet's coma, the cloud of dust and gas that surrounds the nucleus, and its tail more easily.

The comet will be very low at your starting time. It will gradually rise higher into better, clearer view as the minutes pass, but the sky will be brightening too. At some point you'll catch the best balance between the comet being too low and the sky being too bright.

That's for the morning of July 10th. Each morning after that, the comet will be a little farther to the left. By July 14th it will be two fists at arm's length to Capella's lower left.

Comet NEOWISE is gradually fading as it draws away from the Sun, but meanwhile it's edging nearer to Earth. The comet will be closest to Earth, 64 million miles away, on July 23rd.

Find the Comet: July 14th and after

From the 14th onward, the comet's motion will have shifted its best viewing opportunity to the evening sky. By then Comet NEOWISE might no longer be visible by eye, but the chance of glimpsing it improves if you can find a location that's free of light pollution.

Start looking about 1 hour after sunset, when you'll find it just over the northwestern horizon as the last of twilight fades into darkness. Look about three fists below the bottom of the Big Dipper, which is hanging down by its handle high above, and from there perhaps a little to right.

Every evening thereafter the comet will be getting dimmer, but it will also be getting higher up as twilight ends. On the evening of the 23rd, when Comet NEOWISE is its closest to Earth, locate it by first noting the two stars at the bottom of the Big Dipper's bowl. Then draw an imaginary line through them and toward lower left to a point in the sky a little more than one fist away. But by that date you'll almost certainly need binoculars or a telescope.

Want to try taking take pictures? Bring a tripod and a camera that can take time exposures several seconds long. Unfortunately, even the best phone cameras will give mediocre results. What you really want is a DSLR camera with a telephoto lens.