When I started hearing the buzz in the astronomy community about how Comet 46P/Wirtanen was coming in hot through our Solar System, my ears proverbially perked up. A quick Google search revealed that this is a truly historic apparition and one that justly deserves the buzz. (The term “apparition,” in astronomy, refers to the appearance or time when a comet, especially a periodic one, is visible.)
The comet was discovered, in 1948, by Carl Wirtanen (hence its name) at the Lick Observatory, in California, with an orbit of about 5.5 years where it passes close to Jupiter. This fairly short orbital interval means that we get alternating “good” and “bad” apparitions, and this year is going to be an especially great one. Because it passes close to Earth, it is considered to be an ideal target on which to land a spacecraft to study it closely —it was the original target of the ESA’s Rosetta mission, but its launch was delayed and the window closed to rendezvous with Wirtanen, so it instead successfully landed (re: intentionally crashed) on comet 67P, in 2016.
Okay, so what is so special about Comet Wirtanen?
1. It’s the 10th-closest comet to Earth in modern times.
2. It’s part of a small family of comets called “hyperactives,” which are defined by high activity levels and seem to emit more water than they should for the relatively small size of their nucleus. This means that when it reaches its closest approach to the sun (its perihelion) on December 12th 2018, it has the possibility for a spectacular tail.
3. It will be near to its opposition during its close approach, so it will be visible for most of the night. It will also be visible for many hours in the months before and after its close approach, allowing many backyard astronomers to begin viewing it through their telescopes. This means that, at the time of this article’s publication date, it will already be visible to many of our readers.
4. Because of the first three points above, the comet will be bright. Magnitude 3 bright… which means it will be visible with the naked eye! Generally, most people can see Magnitude 5 objects with just their eyes, so a Third Magnitude comet will still be visible even if there is some light pollution.
As of this writing, its increasing brightness is following the predicted curve, so by all appearances (pun intended), we can expect it to live up to the Mag 3 hype. On the off-chance that it falls a little short, it will still be bright, if not naked-eye-bright, a pair of binoculars or a small telescope will reveal it to you. Personally, I’ll have my comet-watching rig set up, consisting of Fujinon 16x70 binoculars mounted on a StarLight Innovation PL1 Parallelogram mount and Tri-Light Tripod. This will give me a steady and highly comfortable viewing platform that still allows me generous freedom of movement, with the ability to digi-scope the comet through an eyepiece and capture a clear shot if I want.
Since the comet is going to be moving around the night sky quickly in its orbit, there’s no accurate way to tell you where it will be on a day that you’re going to go out and view it. To find it during the lead-up to and after its peak, on December 12th, I suggest that you grab an astronomy app for your smartphone and use its search function to find the comet. I personally use Sky Guide, but pick one that you like.
Generally, going into the middle of December, you’ll be able to find it in the East around the constellation Taurus and the Pleiades star cluster.
The University of Maryland has launched the Comet Wirtanen Observing Campaign, an extensive study of the comet, if you are looking to learn more. For those who are interested in astronomy, or want to gauge your kid’s interest, going out and viewing Comet 46P/Wirtanen is a unique opportunity to enjoy a truly rare phenomenon that you won’t want to miss—and you only need some basic gear that you’ll find yourself using again and again!
Do you have experience viewing comets? Have you seen this one in the past? Got plans for a comet party? Do you have one named after you? We want to hear all about it. Comment below and we’ll talk. Now go grab some gear and get outside.
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