Good news! You needn’t get up at dawn to see Comet NEOWISE. Starting this week it will appear low in the northwestern sky at dusk. I’ve been observing during evening twilight the past two nights beginning just after 10 o’clock until about 11:30 p.m. From many mid-northern latitude locations the comet will appear about 5° (three fingers held together horizontally against the sky) above the horizon staring an hour to an hour 15 minutes after sunset. You can still see the comet at dawn until July 18, but you may find evenings more convenient.
The reason NEOWISE is visible at both dusk and dawn through mid-July is because it’s located so far north in the sky. From many locations it either never sets or dips briefly below the horizon before rising again. Like Ursa Major the Great Bear the comet is currently circumpolar — it circles the Pole Star and never sets. It appears at dusk in the northwestern sky, nearly touches the northern horizon around midnight and then rises anew in the northeastern sky.
On July 12th I caught sight of NEOWISE in 10x50s at 10:10 p.m. (one hour 10 minutes after local sunset), when I could easily see its star-like head and short tail. By 10:30 p.m. it was visible with the naked eye, and at 11 p.m. — 2 hours past sunset — the soft, streak-like tail had grown to 6°. Binocular views were superb! Make sure you focus them first on a bright star before seeking the comet. I joined several friends at a socially acceptable distance. Everyone saw the comet with the naked eye once the sky got dark.
Use the accompanying map to help you find it. NEOWISE is climbing higher and higher as it crosses the faint constellation Lynx and from there into Ursa Major where the Big Dipper will make it a snap to find. So again — start looking around 10 p.m. local time and stick with the comet as the sky darkens for an ever-improving view. Comet NEOWISE has faded to around magnitude 2 (bright as a Big Dipper star), but the tail remains bright and long, especially in binoculars, so try to catch it the next clear night.
With bright head and streaky tail NEOWISE looks very similar to a meteor, so you might expect it to move quickly across the sky. But while it’s traveling around the sun at tens of thousands of miles an hour the comet is so far away that it only appears to move about a thumb’s width of sky each night. On July 13 it stands more than 75 million miles (121 million km) away from the Earth. Closest approach occurs on July 23 at a distance of 64 million miles (103 million km). Meteors, most of which are dust grains shed by comets, enter the atmosphere only 60-70 miles above our heads.
Want to take a photo? A DSLR on a tripod is all you need. You can even get a picture with basic cellphone as long as there’s still twilight in the sky (see above). If you use a DSLR, put the camera and lens in manual “M” mode then activate the camera’s live view feature. Live view gives a live view of the sky on the back viewing screen. Point to a bright star and center it in the field of view then press the little magnifier button to enlarge the star. Manually focus until the star is as tiny and sharp as possible. Press the live view button again to close, then set your ISO to 1600, open the lens to its widest aperture (usually f/2.8, f/3.5 or f/4.5) and expose for 2-3 seconds in twilight and 5-20 seconds if the sky is dark. Look at the back screen to see how you’re doing and adjust exposure time as needed.
Good luck and clear skies!