APOD: December's Comet Wirtanen (2018 Dec 07)

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APOD: December's Comet Wirtanen (2018 Dec 07)

Post by APOD Robot » Fri Dec 07, 2018 5:09 am

Image December's Comet Wirtanen

Explanation: Coming close in mid-December, Comet 46P Wirtanen hangs in this starry sky over the bell tower of a Romanesque church. In the constructed vertical panorama, a series of digital exposures capture its greenish coma on December 3 from Sant Llorenc de la Muga, Girona, Catalonia, Spain, planet Earth. With an orbital period that is now about 5.4 years, the periodic comet's perihelion, its closest approach, to the Sun will be on December 12. On December 16 it will be closest to Earth, passing at a distance of about 11.6 million kilometers or 39 light-seconds. That's close for a comet, a mere 30 times the Earth-Moon distance. A good binocular target for comet watchers, Wirtanen could be visible to the unaided eye from a dark sky site. To spot it after dusk on December 16, look close on the sky to the Pleiades star cluster in Taurus.

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Re: APOD: December's Comet Wirtanen (2018 Dec 07)

Post by Iksarfighter » Fri Dec 07, 2018 8:22 am

Cant access full image, link broken.

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Re: APOD: December's Comet Wirtanen (2018 Dec 07)

Post by Boomer12k » Fri Dec 07, 2018 10:45 am

Interesting pic...It is almost like a light pillar coming up off the Church...

I hope we have good weather around the 16th...we have been clear but freezing, and it is supposed to warm and be cloudy with rain...sigh...

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Re: APOD: December's Comet Wirtanen (2018 Dec 07)

Post by webdan » Fri Dec 07, 2018 12:48 pm

Iksarfighter wrote:
Fri Dec 07, 2018 8:22 am
Cant access full image, link broken.
I knew I had recently seen this image...

http://spaceweathergallery.com/indiv_up ... _id=149608

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Re: APOD: December's Comet Wirtanen (2018 Dec 07)

Post by BDanielMayfield » Fri Dec 07, 2018 2:58 pm

Will its tail ever be visible? A comet with no tail is like ... (you supply the metaphor).
"Happy are the peaceable ... "

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Re: APOD: December's Comet Wirtanen (2018 Dec 07)

Post by Chris Peterson » Fri Dec 07, 2018 3:14 pm

BDanielMayfield wrote:
Fri Dec 07, 2018 2:58 pm
Will its tail ever be visible? A comet with no tail is like ... (you supply the metaphor).
It doesn't currently have a dust tail. Whether it will form one or not remains unknown. It does have a gas tail which is visible in images (but too faint to see with the eye). However, that tail is disappearing behind the comet as it gets closer to us, so when the comet is at its brightest in another week or two we probably won't see any tail, unless it starts ejecting dust.
Chris

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Re: APOD: December's Comet Wirtanen (2018 Dec 07)

Post by neufer » Fri Dec 07, 2018 7:04 pm

Chris Peterson wrote:
Fri Dec 07, 2018 3:14 pm
BDanielMayfield wrote:
Fri Dec 07, 2018 2:58 pm

Will its tail ever be visible? A comet with no tail is like ... (you supply the metaphor).
It doesn't currently have a dust tail. Whether it will form one or not remains unknown. It does have a gas tail which is visible in images (but too faint to see with the eye). However, that tail is disappearing behind the comet as it gets closer to us, so when the comet is at its brightest in another week or two we probably won't see any tail, unless it starts ejecting dust.
https://en.wikipedia.org/wiki/46P/Wirtanen wrote: <<Russian forecaster Mikhail Maslov had predicted that the Earth's orbit would cross Comet Wirtanen's debris stream as many as four times between December 10 and December 14, 2012. As there had not previously been an encounter with this debris stream, it was not certain whether or not a meteor shower would be visible from Earth, but there was speculation that a shower with as many as 30 meteors per hour might occur. Observers in Australia reported that on the night of December 14, 2012, as many as a dozen meteors were seen emanating from the predicted radiant in the constellation of Pisces.

The comet was the target for the proposed Comet Hopper mission, which reached the finalist stage in the NASA Discovery program. It was one of only three missions in that selection to have a more detailed study. The selection process was ultimately won in 2012 by the InSight mission, a Mars lander. The Comet Hopper was designed to use the ASRG, the Advanced Stirling Radioisotope Generator.

The Comet Hopper mission, if it were selected, would have had multiple science goals over the 7.3 years of its nominal lifetime. At roughly 4.5 AU the spacecraft would rendezvous with Comet Wirtanen and begin to map the spatial heterogeneity of surface solids as well as gas and dust emissions from the coma - the nebulous envelope around the nucleus of a comet. The remote mapping would also allow for any nucleus structure, geologic processes, and coma mechanisms to be determined. After arriving at the comet, the spacecraft would approach and land, then subsequently hop to other locations on the comet. As the comet approached the Sun, the spacecraft would land and hop multiple times. The final landing would occur at 1.5 AU. As the comet approached the Sun and became more active, the spacecraft would be able to record surface changes.

Also, 46P/Wirtanen was the original destination of the European Space Agency's Rosetta spacecraft mission, but launch delays meant that the comet was no longer easily reachable and another periodic comet, 67P/Churyumov–Gerasimenko, was chosen as the mission's target instead.>>
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Re: APOD: December's Comet Wirtanen (2018 Dec 07)

Post by RJN » Fri Dec 07, 2018 8:19 pm

Iksarfighter wrote:
Fri Dec 07, 2018 8:22 am
Cant access full image, link broken.
Thanks! Fixed it.

- RJN

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Re: APOD: December's Comet Wirtanen (2018 Dec 07)

Post by neufer » Sat Dec 08, 2018 6:19 pm

Art Neuendorffer