In early July, we’re lucky to have a visit from the comet C/2020 F3, which is visible to the naked eye. If you don’t mind getting up at 4 AM, you can see it yourself! Such comets are relatively rare—and they’re both beautiful and fascinating to look at, especially if you know what they’re all about. Here’s the scoop:
You can think of a comet as a (temporarily) gleaming “snowball” in space. These ancient masses of rock and ice, dating from the beginning of our solar system, spend most of their time in our system’s far reaches, where it’s both dark and cold—but when a comet’s orbit brings it close to the Sun, it becomes brilliantly illuminated, like comet C/2020 F3 is now.
Under this much radiation, part of the comet’s material gets vaporized and blown off the comet, resulting in a tail that streams “downwind,” away from the Sun—this is what gives comets their familiar appearance. (If you watch C/2020 F3 day by day, you may even notice the angle of the tail shift as the comet arcs past the Sun.) Since this is currently a pre-dawn comet, the tail points away from where the Sun will rise.
As currently seen from suburban locations, comet C/2020 F3 appears somewhat more than a thumb’s width in length, when your fist is held straight out in front of you. Around 4 AM, it’s just high enough to get over a single-story dwelling across the street from you—about a fist’s width above the northeastern horizon (hold your arm in front of you, with the bottom of your fist at eye level, while making a “thumb’s up” sign). The comet still looks good around 4:30, but by 4:45, twilight is definitely washing it out, and the comet will fade into the sunrise before 5 AM. Note that the comet’s position will shift morning by morning—see the chart.
It will be better to find an open area, perhaps a nearby park, so that you can have an open horizon. Better still is a trip away from city lights, as light pollution will wash out the comet’s tail; the comet will appear much larger under dark, country skies. Either way, if you at least have an empty horizon, then you can look earlier, when the sky is a bit darker, improving your view further.
Getting away from extraneous light is a key point—from my front yard in Denver, I can spot the comet without optical aid around 4 AM—but I have to stand in the shade from a nearby streetlight and block the porch light of a neighbor’s house (it’s right in my line of sight). Without those extra steps, the glare obscures the comet.
If your conditions aren’t great or you’re just not having any luck, use a pair of moderate binoculars (like 7x35s) to sweep the area—I’ve found that once I’ve narrowed the comet’s location with binoculars, the comet is much easier to pick up naked-eye. If all else fails, give up on the naked-eye view and just use the binoculars—it’s a spectacular sight! Find something to rest your elbows on—your view will be steady and you can look for longer without tiring out your arms.
One last note about this comet: It gets higher in the sky each morning until about the 10th of July, and then sinks towards the horizon in the following days. The comet’s orbit then takes it into our evening sky, where it should be visible by the 12th or 13th, low in the northwest.
The comet will get higher in the evening sky, and thus easier to see, each night after—so mid-month views could be great, and certainly more convenient for most folks than the current, pre-dawn view. However, comets are known to break apart, especially ones like C/2020 F3, which don’t show up here often (C/2020 F3 orbits the Sun once in about 7,000 years). So sleep in now and wait for mid-month if you want to, but you might miss the show!
Clear skies to ya….