Wirtanen, the Christmas 2018 comet: how, where and when – a quick guide to comet 46P
Ok, you have surely heard about this: comet Wirtanen is ready to put its show out there, just on time for Christmas. Here you will find a few tips to look for and enjoy this nice “tailed” star, with the bonus of the Gemind meteor shower!
* NB: versione in Italiano qui*
Comet 46P/Wirtanen, discovered on 17 Jan. 1948 by the US astronomer Carl Wirtanen, is a periodic one, orbiting around the Sun with a period of 5.4 years. Its next perihelion (when the comet is at its minimum distance from the Sun) will be on 12 Dec. 2018 and a few days later, on Dec. 16, Wirtanen will be at its minimum distance from the Earth, about 11 millions of km: this will make it the 20th cometary closest approach ever.
Comet 46P is now climbing the skies, becoming visible in our Northern hemisphere, preparing the best of its how. For this, we are pleased to share with you the star chart above, showing where comet Wirtanen will be in the sky from 3 Dec., when the it is at last reasonably high in our sky, to 17 Dec., before the full Moon (22 Dec.) will flood everything with its light. Positions are given for the written dates at 21:00 UTC. After the full Moon, just on time for Christmas, we will have a couple of hours of dark skies soon after sunset to see comet 46P again, though slowly fading.
There are a couple of special dates in that time interval. On 12 Dec., the comet will reach its perihelion, the minimum distance from the Sun about 150 millions of km. On 16 Dec., comet 46P will be at its minimum distance from the Earth, about 11 millions of km. These dates will be the milestone of this apparition, so you will want to look for the comet those nights, at least! We can expect to see the comet peaking in brightness at magnitude 3.5 or so, being a bit harder to see than stars of similar magnitude, the comet being diffuse.
Night after night, Wirtanen will be better and better visible and brighter, with the opportunity to see it with the naked eye, as a fuzzy object, so different from a pinpoint, ordinary star. As you can see, many bright stars are around, so they really help us locating the object, west of Orion, across Taurus, the Bull.
We said the comet can been spotted with the unaided eye. This is true, provided you will observe from a remote site, offering a dark sky with no light pollution. A binocular will certainly improve the experience, possibly showing the tail, which has been intermittently reported over the last ten days or so. At its climax, the comet will project its ion tail along the line of sight, beyond the nucleus, this will make harder for us to see it.
Please note: we are not saying this one will be an epic comet. The chance for you to see it without any optical device is strongly connected with the quality of your sky. We can expect this comet to be visible to our eyes as a diffuse light in the sky, if we are far from the cities, otherwise Wirtanen can be easily missed. If you have a binocular around, use it, it will make a huge difference.
While you will be out there, do not forget to look up as much as you can! On the nights of 13 and 14 dec. the Gemind meteor shower will peak in its activity (expected rate: 100 meteors per hour), under very good skies conditions (no Moon around), offering such a super bonus! Can you imagine an image of the comet, capturing a Geminid meteor, too? No? Give it a try!
Let’s see how comet Wirtanen will perform, we are ready to exploit this Christmas gift! Meantime, here you can see some images we grabbed so far.
NB: we will show comet Wirtanen live, online on 12 and 16 Dec.: check here for more!
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