Skywatchers are treated to a naked-eye comet as NEOWISE emerges into the the dawn sky.
Whatever you do, see this comet. I almost couldn't believe my eyes when I pointed a pair of 10×50 binoculars at NEOWISE on July 7th at dawn. OMG. What a sumptuous view! The comet's head, a bright, yellow pea, sprouted a 3° pale orange tail that arched upwards in a most elegant way. With the naked eye, I saw a delicate streak of light about 1.5° long with a tiny, star-like coma. The image of a faint meteor jumped to mind.
Far to the right of NEOWISE, Venus and Aldebaran glimmered in Taurus. Comparing the comet to Aldebaran (magnitude +0.9), I estimated its brightness at magnitude 1.4, by far the brightest comet to grace our skies since PanSTARRS (C/2011 L4) in March 2013. And what timing. Just what we needed for the COVID-19 blues!
NEOWISE survived its July 3rd perihelion in grand form, glowing around magnitude 0, bright enough for some amateurs to spot it the very same day. It has since faded to magnitude 1.5–2 but its beauty is undiminished. In fact, the comet has become more extraordinary over the past few nights because it's slowly climbing higher into a darker sky at the same time that the Moon is waning from full to third quarter. On July 8th the tail length had doubled to 6° (my estimate), and the comet appeared more obvious to the naked eye than the morning prior.
I've heard from observers who've observed NEOWISE everywhere from the countryside to Los Angeles. The news is good. Check out this report from Richard K. Mitchell:
"Here in Albuquerque, the comet was a beautiful sight this morning (July 7th). I could see it fairly easy with the naked eye but not an obvious sight, but very impressive sight in 10×50 binoculars. So I would encourage anyone in the “burbs” or a smaller city to give it a try."
Or this from Jim Twellman on July 8th: "Observed once again from the I-64 overpass at Lake St Louis (an outlying suburb of St. Louis, MO. ) The comet was easily visible in 10 × 50s but was spectacular in the 15×70s. Estimate 2.0 magnitude."
I don't want to give the impression that NEOWISE is super-easy to see — you still need know where to look — but once seen you'll return to it with ease. Thank goodness for Capella. Located in the comet's vicinity, this bright star points the way for novice and amateur observers alike.
Although NEOWISE sits quite low and appears faint at the start of dawn, it quickly brightens as it gains altitude, offsetting (at least for a time) the intensifying twilight. The best time slot to see the object through July 11–12 is from 2 hours to 1 hour before sunrise. Click here to find when the Sun rises for your location. With 10×50 binoculars I've been able to follow the comet up to within 40 minutes of sunup.
Through a telescope the colors are even more intense, but the most remarkable sight is the comet's bifurcated tail — split in two by a dark, U-shaped channel. This feature is also visible in binoculars and photographs, but far more dramatic in a scope. I use a portable 10-inch f/4.5 Dobsonian at low magnification (48×). Bifurcated tails appear in comets that are actively producing massive quantities of dust either after a close passage to the Sun or during a major outburst.
NEOWISE has a prominent dust tail, formed when dust-rich ice vaporizes in the Sun's heat. Micron-size dust particles scatter sunlight and glow faintly yellow. An enormous amount of dust must concentrate near the false nucleus because its yellow color is unmistakable. The comet is also developing a fainter, blue-hued ion tail from fluorescing carbon monoxide. Few observers have noted the ion tail visually yet, but you can't miss it in Michael Jaeger's photo.
Dawn comet viewing will be best through about July 18th, with the evening apparition starting about July 12th and continuing the remainder of the summer. Between July 12–18 you can observe it at both dusk and dawn.
So set your alarm and plan to be out about 2 hours before sunrise (for now). Find a location with a good view of the northeastern sky, and don't forget to bring binoculars and a camera. Most mobile phone photos will look grainy, but a basic DSLR on a tripod at ISO 800 with a 2-second exposure will net you an image you'd be happy to share on social media.
I hope good weather comes your way so you can see Comet NEOWISE while it's still bright. Nothing would make me happier. By the time I wrapped up my July 7th observation I felt like I was floating on air with light beams shooting from my fingertips. As the comet vaporizes to create one of the most beautiful sky sights in years, you may just find that it will melt your heart, too.
Update July 11: Despite fading to around magnitude 2, Comet NEOWISE is becoming easier to see with an ever-lengthening tail. I traced it to 5° with the naked eye and 9° with binoculars on July 11. The nucleus has faded somewhat but still glows intensely yellow due to a combination of dust and sodium emission. Also, the comet is entering the evening sky just now particularly for viewers in the northern U.S., Canada and northern Europe.