Time To Check In With Comet 46P/Wirtanen

This wide-angle view of Comet 46P/Wirtanen includes Orion and several bright stars for reference. It was taken last night (Dec. 7) with a 35mm lens on a tracking mount and time exposure of 80 seconds. Bob King

Time to check in on our current favorite comet. It was discovered by American astronomer Carl Wirtanen in January 1948. The “46P” part refers to it being the 46th periodic (P) comet discovered. Periodic comets, also known as short-period comets, revolve around the sun in fewer than 200 years. Those that take longer are called long-period comets. Wirtanen completes an orbit every 5.4 years.

Taken with a 200mm telephoto lens, this photo resembles the impression through binoculars except that the nuclear region appears sharper and more distinct here than with the eye. Can you see the face the comet makes with the “eye” to its left, “nose” below and a “mouth” of several stars below the nose. Bob King

Under clear, dark skies last night (Dec. 7) I could see the comet without any optical aid because I knew exactly where to look. Even then it was little more than a faint smudge glowing at magnitude 5. But hey, it’s official — we have a naked-eye comet!  Binoculars gave a great view of a moon-sized fuzzy blob of fuzz with a brighter center. In a 15-inch telescope Wirtanen was a big, gassy-looking thing with a pale blue color and small, brighter core called the nuclear region. The nuclear area is the bright central pip that really pops in recent photos of the comet. It’s much more obvious in images than seeing it visually in binoculars.

Glory be! This is the view through a small telescope on Dec. 6, 2018. We see the fuzzy ball or ‘coma,’ a short gas tail, and the bright nuclear region, where much of the comet’s dust and gas is concentrated. Damian Peach

I also teased out slightly brighter streak of light embedded in the coma’s head pointing to the northeast. This is the gas tail. Because of 46P’s near head-on approach to Earth, we won’t see an obvious tail for some time. The gas tail shows up clearly as a narrow streak in time-exposure photos. Over the coming week, the comet is expected to brighten further to magnitude 3, so it should become more obvious from dark skies. I’ve heard that city observers are having a tough go of seeing it in light pollution. That’s not surprising given how soft and fuzzy it appears.

Use this map to help you spot the comet. It shows stars to magnitude 6.5. Although the comet’s position is shown for 9 p.m. (Central Time), you can start observing much earlier in the evening. I’d suggest around 7 p.m. local time, when the comet will be well up in the southeastern sky. Chris Marriott’s SkyMap with additions by the author

I’ve included the map again to help you make the best of the current run of moon-free skies to see 46P/Wirtanen at its best. When you’re using binoculars, point them at the comet’s position and look for a soft, misty glow like a little puff of cloud. As Wirtanen approaches the Earth, it picks up speed, moving several degrees northward and higher in the sky each night. That and its expected brightening as it passes closest to us on the 16th should make it easier to see in the coming week. To make sure you don’t miss it, go for a drive in the country. You’ll also be treated to great views of the winter Milky Way, now rising in the eastern sky in Gemini and Orion like chimney smoke on a still night. Don’t forget those binoculars!

6 Responses

  1. Edward M. Boll

    Been too cloudy here. I ways going to look for it on the 1st and last night. By next week my intents to look for it will increase. I have seen no comets yet in December. I hope that I cannot say the same thing by the 31st. Little disappointed yet that the average views still put it around magnitude 5.5.

    1. astrobob

      I really, really hope you get a clear night. Good luck and write back when you see it with your impressions.

  2. Richard K. Mitchell

    Last night was the first clear night in about three or four days, observed Comet 46P in 10×50 binoculars at about mag.4.5 – 5 and is looking very nice. I may have even spotted it with the naked eye but not sure.

  3. kevan hubbard

    Managed to spot the comet from a village called ruswarp just west of Whitby, Dracula country,in northern England.i think that it is just naked eye?it may have a tail tracking off to the north?very easy in my 8×25 monocular.i saw it on the 9th December at about 22hr..it was on the border of cetus and eridanus by two faint, guessing 5th magnitude?,stars.looks like a bright version of m33. I think that it’s the brightest comet I’ve seen since the Holmes comet.

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