APOD: Comet ISON from STEREO (2013 Nov 23)

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APOD: Comet ISON from STEREO (2013 Nov 23)

Post by APOD Robot » Sat Nov 23, 2013 5:25 am

Image Comet ISON from STEREO

Explanation: Still intact, on November 21 Comet ISON (C/2012 S1) swept into this animated field of view (left) from the HI-1 camera on the STEREO-A spacecraft. The camera has also captured periodic Comet Encke, Mercury, and Earth, with the Sun cropped out of the frame at the right, the source of the billowing solar wind. From STEREO's perspective in interplanetary space, planet Earth is actually the most distant of the group, seen in its orbit beyond the Sun. Mercury is closest, but both planets are still so bright they create sharp vertical lines in the camera's detector. Both comets clearly sport substantial tails, but ISON is closer to the camera and will continue to move more rapidly through the field. Cameras on STEREO and SOHO spacecraft will be able to follow Comet ISON as it falls towards its close encounter with the Sun on November 28, even as ISON gets more difficult to see in the bright dawn skies of planet Earth.

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Re: APOD: Comet ISON from STEREO (2013 Nov 23)

Post by Ann » Sat Nov 23, 2013 5:46 am

Comet ISON did not make much of a show here, but the tail of comet Encke is fantastic! It must, of course, be the solar wind that ruffles the tail of Encke so much.

Fantastic to see. How lucky we are that we are no closer to the Sun than we actually are! (Well, the habitable zone and all that jazz...)

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Re: APOD: Comet ISON from STEREO (2013 Nov 23)

Post by Cousin Ricky » Sat Nov 23, 2013 6:09 am

Does anyone know of a chart that shows where Comet ISON is? :?: :?: :?: I've looked all over the place, and the only chart I can find is an outdated chart on Wikipedia. CIOC refuses to post a chart on the grounds that it's not yet naked eye. Huh? By that logic, no one should ever post a chart of Neptune or Pluto!

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Re: APOD: Comet ISON from STEREO (2013 Nov 23)

Post by owlice » Sat Nov 23, 2013 7:18 am

A closed mouth gathers no foot.

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Re: APOD: Comet ISON from STEREO (2013 Nov 23)

Post by Boomer12k » Sat Nov 23, 2013 3:40 pm

That is really awesome!

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Re: APOD: Comet ISON from STEREO (2013 Nov 23)

Post by biddie67 » Sat Nov 23, 2013 3:57 pm

Thanks Owlice !!!

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Re: APOD: Comet ISON from STEREO (2013 Nov 23)

Post by perspichaos » Sat Nov 23, 2013 4:49 pm

I'm confused as to why Earth and Mercury appear to be illuminated from the left when the sun is cropped out of the right side of the frame.

I paused the animation on Nov 20th over on this page http://stereo-ssc.nascom.nasa.gov/comet_ison/ to get a full perspective of the relationship between all the actors participating in the image, and it looks to me like both plantes should be lit from the right.

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Re: APOD: Comet ISON from STEREO (2013 Nov 23)

Post by Chris Peterson » Sat Nov 23, 2013 5:07 pm

perspichaos wrote:I'm confused as to why Earth and Mercury appear to be illuminated from the left when the sun is cropped out of the right side of the frame.
You are seeing artifacts associated with saturated pixels- blooming, wrapped intensity values, maybe more. There is neither enough resolution nor dynamic range to reveal any details at all about the direction of illumination.
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Re: APOD: Comet ISON from STEREO (2013 Nov 23)

Post by perspichaos » Sat Nov 23, 2013 5:19 pm

That was my suspicion.

Thanks, Chris!

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Re: APOD: Comet ISON from STEREO (2013 Nov 23)

Post by Vitaly Goranskij » Sat Nov 23, 2013 6:18 pm

Why Earth is nearer to the Sun then Mercury?

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Re: APOD: Comet ISON from STEREO (2013 Nov 23)

Post by ta152h0 » Sat Nov 23, 2013 6:38 pm

if I may quote a couple guys from the past ( Cheech and Chong ) " :D Cool man, way cool "
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Re: APOD: Comet ISON from STEREO (2013 Nov 23)

Post by Chris Peterson » Sat Nov 23, 2013 7:04 pm

Vitaly Goranskij wrote:Why Earth is nearer to the Sun then Mercury?
stereo-a.gif
It's just a matter of perspective. The image was made by the Stereo-A spacecraft, seen as "A" on this chart of where everything actually was in the inner system at the time.
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Re: APOD: Comet ISON from STEREO (2013 Nov 23)

Post by PacRim Jim » Sat Nov 23, 2013 7:11 pm

Why is the earth closer to the sun than is Mercury?

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Re: APOD: Comet ISON from STEREO (2013 Nov 23)

Post by BMAONE23 » Sat Nov 23, 2013 8:18 pm

The STEREO web site has a good animation showing the relative locations of STEREO A & B and the planets at the time
http://stereo-ssc.nascom.nasa.gov/comet_ison/

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Re: APOD: Comet ISON from STEREO (2013 Nov 23)

Post by bls0326 » Sat Nov 23, 2013 11:38 pm

Cousin Rickey: Here is a link to a skychart that looks good to me. Can be customized quite a bit.

http://www.skyviewcafe.com/skyview.php

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Re: APOD: Comet ISON from STEREO (2013 Nov 23)

Post by mrdkt@att.net » Sun Nov 24, 2013 1:35 am

PacRim Jim wrote:Why is the earth closer to the sun than is Mercury?
In the description given, you state "The camera has also captured periodic Comet Encke, Mercury, and Earth, with the Sun cropped out of the frame at the right." It would appear the answer to the quote is a bit misleading since, even though Earth could be in a position with the Sun at the right, Mercury would still have to be on the opposite side of Earth when viewed from A (Stereo). Perhaps I am misunderstanding something, or the details are incorrect in the accompanying drawing.

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Re: APOD: Comet ISON from STEREO (2013 Nov 23)

Post by Chris Peterson » Sun Nov 24, 2013 1:41 am

mrdkt@att.net wrote:
PacRim Jim wrote:Why is the earth closer to the sun than is Mercury?
In the description given, you state "The camera has also captured periodic Comet Encke, Mercury, and Earth, with the Sun cropped out of the frame at the right." It would appear the answer to the quote is a bit misleading since, even though Earth could be in a position with the Sun at the right, Mercury would still have to be on the opposite side of Earth when viewed from A (Stereo). Perhaps I am misunderstanding something, or the details are incorrect in the accompanying drawing.
Look at the orbit diagram I posted above. From Stereo-A you see, from left to right, ISON, Mercury, Earth, and the Sun. Just like the video shows.
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Re: APOD: Comet ISON from STEREO (2013 Nov 23)

Post by geckzilla » Sun Nov 24, 2013 4:00 am

Conclusion: Three-dimensional space interpreted as two-dimensional space is confusing to people.
Just call me "geck" because "zilla" is like a last name.

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Re: APOD: Comet ISON from STEREO (2013 Nov 23)

Post by Cousin Ricky » Sun Nov 24, 2013 4:01 am

owlice wrote:Courtesy of AstroBob.
Thanks, Owlice!

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Re: APOD: Comet ISON from STEREO (2013 Nov 23)

Post by ta152h0 » Sun Nov 24, 2013 4:05 am

requires algebra 2 at least, just saying .......
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Re: APOD: Comet ISON from STEREO (2013 Nov 23)

Post by alter-ego » Sun Nov 24, 2013 5:23 am

Chris Peterson wrote:
mrdkt@att.net wrote:
PacRim Jim wrote:Why is the earth closer to the sun than is Mercury?
In the description given, you state "The camera has also captured periodic Comet Encke, Mercury, and Earth, with the Sun cropped out of the frame at the right." It would appear the answer to the quote is a bit misleading since, even though Earth could be in a position with the Sun at the right, Mercury would still have to be on the opposite side of Earth when viewed from A (Stereo). Perhaps I am misunderstanding something, or the details are incorrect in the accompanying drawing.
Look at the orbit diagram I posted above. From Stereo-A you see, from left to right, ISON, Mercury, Earth, and the Sun. Just like the video shows.
Hopefully, I can add a little more clarity to the discussion.
The first image below shows an extened 10° x 27° field of view from Stereo A on 21 Nov, 000900 UT. The red box accurately shows the objects and brightest background stars in Aries. The extended view shows the Sun is almost 16° to the right of Earth. The second image shows a "top" view of in inner solar system with the orbits of Mercury and Earth present. It replicates the earlier diagram(s), but a maybe clearer with some line-of-sight indicators from Stereo to the objects. The indicators clearly show the left-to-right sequence of the planets wrt Stereo.
27° FoV from Stereo A_21 Nov 13 000900UT.JPG
View from Above_Orbits and Left to Right Indicators.jpg
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Encke & ISON from Mercury

Post by neufer » Sun Nov 24, 2013 12:42 pm

http://www.universetoday.com/106399/comets-encke-and-ison-spotted-from-mercury/ wrote: Comets Encke and ISON Spotted from Mercury
Jason Major, Universe Today, November 14, 2013

<<Two comets currently on their way toward the Sun have been captured on camera from the innermost planet. The MESSENGER spacecraft in orbit around Mercury has spotted the well-known short-period comet Encke as well as the much-anticipated comet ISON, imaging the progress of each over the course of three days. Both comets will reach perihelion later this month within a week of each other.

While Encke will most likely survive its close encounter to continue along its 3.3-year-long lap around the inner Solar System, the fate of ISON isn’t nearly as certain… but both are making for great photo opportunities!

The figure above shows, on the left, images of comet 2P/Encke on three successive days from Nov. 6 to Nov. 8; on the right, images of C/2012 S1 (ISON) are shown for three successive days from Nov. 9 to Nov. 11. Both appear to brighten a little bit more each day.
MESSENGER is viewing these comets from a vantage point that is very different from that of observers on Earth. Comet Encke was approximately 0.5 AU from the Sun and 0.2 AU from MESSENGER when these images were taken; the same distances were approximately 0.75 AU and 0.5 AU, respectively, for ISON. More images will be obtained starting on November 16 when the comets should be both brighter and closer to Mercury. (Source: MESSENGER featured image article.)

Encke will reach its perihelion on Nov. 21; ISON on Nov. 28.

“We are thrilled to see that we’ve detected ISON,” said Ron Vervack, of the Johns Hopkins University Applied Physics Laboratory, who is leading MESSENGER’s role in the ISON observation campaign. “The comet hasn’t brightened as quickly as originally predicted, so we wondered how well we would do. Seeing it this early bodes well for our later observations.”

Unlike ISON, Encke has been known for quite a while. It was discovered in 1786 and recognized as a periodic comet in 1819. Its orbital period is 3.3 years — the shortest period of any known comet — and November 21 will mark its 62nd recorded perihelion. “Encke has been on our radar for a long time because we’ve realized that it would be crossing MESSENGER’s path in mid-November of this year,” Vervack explained. “And not only crossing it, but coming very close to Mercury.”

These early images of both comets are little more than a few pixels across, Vervack said, but he expects improved images next week when the comets make their closest approaches to MESSENGER and Mercury:
http://messenger.jhuapl.edu/news_room/details.php?id=245 wrote:
MESSENGER Mission News
November 14, 2013

<<On November 18, just a few days shy of its perihelion on November 21, Encke will travel within 3.7 million kilometers of Mercury. According to the Minor Planet Center, if Encke came this close to Earth, it would rank as the third closest known approach of a comet to our planet. On November 19, ISON will pass within 36.2 million kilometers of Mercury while at a distance of 71 million kilometers from the Sun.

"By next week, we expect Encke to brighten by approximately a factor of 200 as seen from Mercury, and ISON by a factor of 15 or more," Vervack said. "So we have high hopes for better images and data." Three of MESSENGER's instruments -- MDIS, the Mercury Atmospheric and Surface Composition Spectrometer, and the X-Ray Spectrometer -- will be trained on the two comets and will collect as many observations as payload operational constraints will allow.

There are complicating issues that could impact the volume of data the team gathers, Vervack explained. "Closest approach occurs during what we call a 'hot season,'" he said. "So, for the health of the spacecraft, portions of each orbit must be spent in a thermally safe mode, which precludes gathering data over the entire orbit." The critical observations also happen during a low-downlink period for MESSENGER. "We can't fill up the spacecraft recorder with comet data because doing so could cause a backlog that impacts our primary mission of collecting observations from Mercury," he said. But the team is optimistic that all will go as planned, he said. "We just need the comets to hold up their end of the bargain.">>
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Re: APOD: Comet ISON from STEREO (2013 Nov 23)

Post by Astronymus » Sun Nov 24, 2013 2:42 pm

With that weather we'll never see ISON. :evil:
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Re: APOD: Comet ISON from STEREO (2013 Nov 23)

Post by astrocrazythings » Wed Nov 27, 2013 1:38 am

What is the object, almost directly above the last digit (the # 1) in the time - moving slower than the background stars but moving in the same direction as the Comets, in the direction of the Sun?

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Re: APOD: Comet ISON from STEREO (2013 Nov 23)

Post by neufer » Wed Nov 27, 2013 4:04 am

astrocrazythings wrote:
What is the object, almost directly above the last digit (the # 1) in the time - moving slower than the background stars but moving in the same direction as the Comets, in the direction of the Sun?
Comet Lovejoy :?: : http://asterisk.apod.com/viewtopic.php? ... 97#p214454
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