Comets ISON (brighter) and Encke from November 19-22, 2013 as seen encountering the solar wind. Image via Karl Battams/NRL/NASA-CIOC.
Here was Comet ISON Monday morning, November 25. The comet has edged downward in the eastern, predawn sky. It will encounter the sun on November 28 – Thanksgiving Day in the U.S. Will it survive?
NOVEMBER 25, 2013. There has talk for some days about whether Comet ISON has fragmented. The sungrazing comet experts were saying no, but Monday morning Karl Battams – one of the great communicators at NASA’s Comet ISON Observing Campaign website – said that something is happening to the comet. There are signs it may be fragmenting. He wrote:
There’s evidence that ISON’s nucleus might not be holding up well (by which I mean falling apart!) It was always a possibility…we’ll see!
Later, he added:
It is absolutely conceivable that ISON remains in one piece, and is just being a sungrazer.
In other words, the word isn’t in yet on whether ISON is still intact.
The evidence for ISON’s possible disintegration comes in the form of a rapid drop in emissions, in recent days, from a certain kind of molecule (hydrogen cyanide molecule) known to be embedded in cometary ice. At his Bad Astronomy blog on Slate, Phil Plait explained that it’s the ice of a comet like ISON that holds the comet together. ISON is full of fresh ice. It’s a first-time visitor from the Oort comet cloud surrounding our solar system. If enough ice boils off the comet as it gets closer to the sun, the comet will literally fall apart.
But how much ice has ISON lost? Enough so that the comet will fall apart? Meanwhile, dust has also been observed to be pouring from the comet. These signs could mean that ISON’s nucleus has completely disrupted. Or not.
Why don’t astronomers know what will happen? Karl Battams explained:
… these reports are new, and while they are undoubtedly valid, we do still need to keep observing the comet to be sure what it happening. Remember: Comet ISON is a dynamically new sungrazing comet, fresh in from the Oort Cloud, and the last time we saw an object like this was never! Furthermore, a sungrazing comet just three days from perihelion has never been studied in this kind of detail – we’re breaking new ground here! When we factor in your standard ‘comets are unpredictable’ disclaimer, what we have is a huge recipe for the unknown.
We do know that, after traveling at least a million years from the Oort Cloud, Comet ISON is now plummeting fast toward the sun. Its perihelion or closest point to the sun will be on November 28 – Thanksgiving Day in the U.S. At perihelion, the comet will be traveling at 248 miles per second, encountering solar temperatures of up to 5,000 degrees Fahrenheit.
Thus this week will bring Comet ISON’s moment of truth, its day of reckoning. The comet is close to the sun on our sky’s dome now and won’t be seen from Earth this week except, perhaps, by a few experienced observers. However, NASA and ESA’s fleet of sun-observing spacecraft will be watching it.
If it survives its passage near the sun, Comet ISON will return to our skies in early December, and, indeed, early December may be the best time to try to see the comet … if there is a comet left to see.
Follow the links below below for a Comet ISON viewing schedule and other information.
Comet ISON month-by-month in late 2013.
Why might Comet ISON fragment when closest to the sun?
How bright will Comet ISON be later this year? How long will its ta...
What’s the story on Comet ISON’s August 2013 recovery and brightness?
Will Comet ISON live up to expectations?
Best photos, images, videos of Comet ISON
Comets Encke and ISON on November 25, 2013.
View larger. | Our friend Annie Lewis in Madrid, Spain caught Comet ISON on Saturday morning, November 23, near the planets Mercury and Saturn. Thank you, Annie! Notice that the comet is very low in eastern predawn twilight. Annie’s camera caught it, but your eye may not.
View larger. | Gerald Rhemann in Namibia in SW Africa captured this photo of Comet ISON on November 21, 2013, one week before its encounter with the sun. Visit Gerald’s website Sky Vistas. Used with permission.
View larger. | Our friend on G+, Greg Hogan, composed this view of ISON before dawn on November 19. It’s a telescopic view superimposed on a sky view, and, if you’ll contrast it to Ian’s photo (above), you’ll see that ISON is moving among the stars in the eastern, predawn sky – getting closer to the sunrise. Why? Because it’s getting closer to the sun! Closest: November 28. Afterwards, if it survives its encounter with the sun, the comet will be back in the dawn sky, hopefully brighter. See more photos by Greg Hogan.
View larger. | Here’s a wider view of same part of the sky as on the charts above – as photographed on November 13, 2013 by Annie Lewis in Madrid, Spain. This photo looks east before dawn. It’s the part of the sky in which you’ll find Comet ISON. See the squarish constellation Corvus the Crow? The ‘beak’ of Corvus points toward the star Spica, and Spica has been key to finding the comet in mid- to late November.
This is NOT Comet ISON. There are several jet contrails in this photo, and many are seeing jet contrails and asking if it’s the comet. Answer: no. The comet is not nearly this bright in November 2013. Read more about comets and contrails here. Photo by Elizabeth Warner.
The best time to see Comet ISON should be early December, after its November 28 perihelion – or closest point to the sun – IF the comet survives!
Comet ISON month-by-month in late 2013.
August 2013. As seen from Earth, Comet ISON was behind the sun in June and July, 2013. Its recovery occurred on August 12, 2013 when amateur astronomer Bruce Gary of Arizona spotted it. In August, it was bright enough to be seen by observers using telescopes and other special equipment at dark locations. Look here for August 2013 finder charts for Comet ISON.
September and October 2013. Comet ISON got brighter in September and October, but not bright enough to be easily visible. However, in September and October, amateur astronomers began to photograph it. Check out some of their photos here. The comet was sweeping in front of the constellation Leo then. It passed first near Leo’s brightest star Regulus, then near the planet Mars.Comet ISON will came very near Mars on October 1. Finder charts for Comet ISON for Septemberand October.
View larger. | EarthSky friend on G+, Scott MacNeill, captured this stunning photo of Comet ISON on the morning of November 15, 2013, which was shortly after its outburst began. Thank you, Scott!
View larger. | This image was taken on November 16, 2013. It shows ISON with two wing-like features resembling the letter U. These wing-like structures caused some astronomers to speculate that the comet had begun to fragment. But other astronomers disagreed.
This comet’s orbit will bring it near the sun in November 2013. Some are predicted it’ll be briefly as bright as a full moon then, but, unfortunately, as its brightest it’ll also be near the sun’s glare. Image via NASA’s Jet Propulsion Laboratory
November 2013. November has been an exciting month for Comet ISON! The comet became visible through binoculars in early in the month and then, around November 12, many saw that Comet ISON had had an outburst. It suddenly became much brighter as it approached its November 28 perihelion (closest point to our sun).
Also, in November, Comet ISON passed very close to the bright star Spica, in the constellation Virgo. This bright star helped many find the comet.
Now, in late November, Comet ISON is still in the east before dawn, appearing closer to the place the sun will rise every morning. Why is it drawing closer to the sunrise? Because it’s drawing closer to the sun itself, heading for a November 28 closest point to the sun, also called perihelion. For a few days around perihelion, Comet ISON will be lost in the sun’s glare. Then, if it has survived its close passage near the sun, it may go on to appear in our sky as a bright comet.
November finder charts for Comet ISON here.
By late December, Comet ISON will have moved so far north on the sky’s dome that it’ll become circumpolar for those at northern latitudes on Earth, visible in both the morning and evening. This chart shows the evening view of ISON in late December and early January. Will you need binoculars or a telescope to see the comet then? Maybe.
December 2013. This is likely to be the best month to see Comet ISON, assuming it has survived its close pass near the sun intact. The comet will be visible in the morning sky before sunrise at its brightest; later in the month, it’ll appear in both the morning and evening sky (because it will have traveled so far north on the sky’s dome that it will become circumpolar).
However, don’t wait until late December, for ISON to appear in the evening sky. As ISON’s distance from the sun increases, it’ll grow dimmer. Comet expert John Bortle wrote on June 13:
The crescendo of the apparition will likely occur between December 10th and 14th, when the comet will be best seen just before dawn after the moon sets. Although little or perhaps nothing of the head will remain, the huge tail will loom in the northeastern sky. Almost evenly illuminated over its length, this rapidly fading appendage could [span] almost a quarter of the heavens as seen under good, dark observing conditions.
People all over Earth will be able to see it, but it’ll be best seen from the Northern Hemisphere as 2013 draws to a close. December finder charts for Comet ISON here.
January 2014. Will ISON still be visible to the eye? Hopefully. Only time will tell. On January 8, 2014, the comet will lie only 2° from Polaris — the North Star. And here’s something else that’s fun. On January 14-15, 2014, after the comet itself has passed but when Earth is sweeping near the comet’s orbit, it might produce a meteor shower, or at least some beautiful night-shining or noctilucent clouds. January finder charts for Comet ISON here.
How bright will Comet ISON be later this year? How long will its tail be? No one can answer these questions yet. In his June 13 article published at skyandtelescope.com, comet expert John Bortle explained the reason we can’t know yet how bright Comet ISON will be:
A close solar pass can disrupt and evaporate a comet’s nucleus completely. The intrinsically faintest sungrazer to survive its brush with the sun reasonably intact was Comet Ikeya-Seki in 1965. The long-tailed sungrazers seen in 1880 and 1887 experienced total disruption of their nuclei and dissipated completely within weeks after perihelion. The latest observations of Comet ISON suggest that it’s intrinsically about as bright as those 19th-century objects, so the survival of its head much beyond November 28 is in question.
Comet C/ISON was imaged with the Hubble Space telescope on April 10 using the Wide Field Camera 3, when the comet was 394 million miles from Earth. View larger. Image via NASA, ESA, J.-Y. Li (Planetary Science Institute), and the Hubble Comet ISON Imaging Science Team
Comet C2012 S1 (ISON). Used with permission.
Who discovered Comet ISON? Eastern European and Russian astronomers announced the new comet on September 24, 2012. Discovery magnitude was 18.8 – in other words, extremely faint. Vitali Nevski of Vitebsk, Belarus and Artyom Novichonok of Kondopoga, Russia spotted the comet on CCD images obtained on September 21 with a 0.4-m f/3 Santel reflector of the International Scientific Optical Network (ISON) near Kislovodsk, Russia. Afterwards, astronomers at Remanzacco Observatory in Italy confirmed the comet’s presence with the image above.
Comet ISON recovery photo in August 2013. Amateur astronomer Bruce Gary in Arizona became the first person to spot it after its sojourn behind the sun from our earthly vantage point in June and July. Image by Bruce Gary. Full story of recovery here.
Amateur astronomer Bruce Gary at his Hereford Arizona Observatory became the first to recover Comet ISON when it emerged from the sun’s glare in August 2013.
What’s the story on Comet ISON’s August 2013 recovery and brightness? On the morning of August 12, 2013, amateur astronomer Bruce Gary was using an 11-inch telescope at Hereford Arizona Observatory, pointing only 6 degrees above the eastern dawn horizon, when he became the first to see Comet ISON again after its sojourn behind the sun during June, July and part of August. He did not see the comet with his eye, but created a composite image by stackingseparate images, thereby recording a fuzzy point with an anti-sunward tail at Comet ISON’s exact predicted position among stars.
Read a complete description of Bruce Gary’s remarkable recovery of ...
Comet Lovejoy was a sight to behold from Earth’s Southern Hemisphere in late 2011. Here the comet is reflected in the water of Mandurah Esturary near Perth on December 21, 2011. Image Credit: Colin Legg.
Will Comet ISON live up to expectations? Comet ISON won’t become a legendary comet of the century. Comet ISON might still break into fragments when closest to the sun, as the much-hyped Comet Elenin did around August 2011.
Or, Comet ISON might survive its encounter with the sun as Comet Lovejoy did in late 2011. If so, when it emerges from perihelion (closest point to sun) in late November, it might become visible to the eye. And there is one thing we can count on. That is, if Comet ISON does become a bright comet, visible to the eyes of watching earthlings, it will be beautiful. All bright comets are.
No doubt about it, comets have a mystique. Once considered omens of doom, we now know them as icy visitors from the outer solar system that sweep near our sun, then disappear again into the depths of space, perhaps never to return. People get excited about comets. They aretemporary visitors to our region of the solar system. This comet might not be as bright as hoped, but … it will be watched.
Bottom line: Comet C/2012 S1 (ISON) is headed for a close encounter with our sun in late 2013. It’ll be closest to the sun on November 28 (Thanksgiving Day in the U.S.). Although some thought this comet might become spectacular later this year, the chances of that are now not good. However, we might see a reasonably bright comet. This post contains a month-by-month viewing guide, some history of the comet, and a word about what to expect from Comet ISON.
Source: http://earthsky.org/space/big-sun-diving-comet-ison-might-be-specta...
