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 putting 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, before it leaves us!
* 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 last perihelion (when the comet is at its minimum distance from the Sun) was on 12 Dec. 2018 and a few days later, on Dec. 16, Wirtanen was at its minimum distance from the Earth, about 11 millions of km: that made it the 20th cometary closest approach ever. Now, it is slowly leaving us.
Comet 46P is well placed in the sky for us living in the Northern hemisphere and we are pleased to share with you the star chart above, showing where comet Wirtanen will be in the sky from 18 Dec. to 31 Dec. Positions are given for the written dates at 21:00 UTC. The Moon will be full on Dec. 22, flooding the sky with its light, making the vision of the comet very poor and difficult. 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.
On 23 Dec., in particular, the comet will be close to the bright star Capella, in Auriga, an excellent reference to try to find it. Comet Wirtanen should be still visible to the unaided eye, provided you will observe from a dark site, with no light pollution: it will appear as a fuzzy object, so different from a pinpoint, ordinary star.
Night after night, Wirtanen will fade, so it is best for you to look for it as soon as possible and from the darkest site possible.
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 weeks (and not visible when the comet was at its closest to the Earth).
Please note: we are not saying this one is a epic comet. The chance for you to see it without any optical device is strongly connected with the quality of your sky and your ability to locate it. 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.
Good luck with comet Wirtanen we hope you will find it! Meantime, here you can see some images we grabbed so far.
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