Recent images of Comet ISON along with spectral data. Credit and copyright: Chris Schur.
Undoubtedly, you’ve been seeing the recent images of Comet ISON now that it is approaching its close encounter with the Sun on November 28. ISON is currently visible to space telescopes like the Hubble and amateur astronomers with larger telescopes. But you might be wondering why many images show the comet with a green-ish “teal” or blue-green color.
Amateur Astronomer Chris Schur has put together this great graphic which provides information on the spectra of what elements are present in the comet’s coma.
For the conspiracy theorists out there, the green color is actually a good omen, and lots of comets display this color. The green color is a sign the comet is getting more active as gets closer to the Sun – meaning it is now putting on a good show for astronomers, and if it can continue to hold itself together, it might become one of the brightest comets in the past several years.
“ISON’s green color comes from the gases surrounding its icy nucleus,” says SpaceWeather.com’s Tony Phillips. “Jets spewing from the comet’s core probably contain cyanogen (CN: a poisonous gas found in many comets) and diatomic carbon (C2). Both substances glow green when illuminated by sunlight in the near-vacuum of space.”
Comet ISON on October 4, 2013 as seen over Arizona, viewed with a 12.5″ telescope, over an hour exposure time. Credit and copyright: Chris Schur.
Both are normally colorless gases that fluoresce a green color when excited by energetic ultraviolet light in sunlight.
And if those poisonous gasses sound dangerous, don’t worry. They are spread out in space much too thinly to touch us here on Earth. So don’t fall prey to fear mongers who are out to bilk the masses – like people did in 1910 when Comet Halley made a return to the skies and swindlers pitched their ‘gas masks’ and special ‘comet pills’ for protection. And of course, nothing happened.
But back to the color. Chris Schur provided this info along with his graphic:
Your readers may appreciate knowing why comets can appear this color. The background image is the shot I took with my 12.5″ and an ST10xme CCD camera for 20 minutes in mid-October. A pale coloration of the front of the coma is seen. To the lower left is a shot with the same instrument but with a 100 lpmm (line pair per millimeter) diffraction grating in front of the CCD chip to break out the spectra of the objects in the entire field.
Here ISON is faintly seen to the left of center, and the first order spectra a band to its right. But the real answer comes when we use the software called Rspec to analyze this band of light. The result is on the lower right. Normally reflected sunlight is rather flat and bland, and mostly that is what ISON is right now, reflected from dust. But labeled are two humps in the blue and green parts of the spectrum labeled “C2” for a carbon molecule. This blue/green emission pair is what gives ISON the color.
Chris notes that as the comet nears the Sun, astronomers and astrophotographers will be able to resolve more spectral details in the comet. “It will be exciting to watch the changes as more molecules pop out,” Chris said via email, “and possibly when it is closest to the Sun, we just may see some metal lines like iron or magnesium from MELTED vaporized rock. How exciting!”
And for those who insist there is something nefarious about Comet ISON, take a look at this FAQ from our friend Stuart Atkinson, who hosts the great site Waiting for ISON. He addresses the many conspiracy theories that are out there regarding this comet.
Comet ISON, as seen on October 21, 2013 from Marion, Ohio, USA, using a QHY9 monochrome CCD camera and TEC 140 F7, 5 inch Refractor telescope. Credit and copyright: Cliff Spohn and Terry Hancock.
This beautiful new view of Comet ISON comes from a collaborative effort between astrophotographers Cliff Spohn in Ohio and Terry Hancock in Michigan, taken on October 21, 2013. “The first time in almost two weeks that we have had a break in the clouds and rain we could not miss this rare opportunity to capture ISON using Cliff’s equipment,” said Terry via email. “Credit goes to Cliff for capturing the object while I did the calibration, stacking in CCDStack post processing in CS5 and video editing.”
You can see a timelapse video below, covering 93 minutes of imaging, again on October 21. It’s obvious ISON is still intact and it continues to bright, as it is currently about magnitude 9.
More recent images:
Update: This new one is just in from astrophotographer Damian Peach, and its a beauty! Taken on October 24.
Comet C/2012 S1 ISON captured passing fairly close to the bright barred spiral galaxy M95 in Leo on October 24, 2013. Credit and copyright: Damian Peach.Comet ISON C/2012 S1, Mars, & Regulus on 10-18-2013 Warrenton, Virginia 6:27am EST Canon Rebel Xsi & 170mm lens F6.3, ISO 400, 6 minutes 6 secs. Credit and Copyright: John Chumack.
From John Chumack: “I just had to try just a telephoto on Comet ISON while it was near Mars,” John said via email. This view shows Comet ISON (C/2012 S1) near Mars and Regulus, the brightest star in the constellation Leo. This image was taken on October 18, 2013 from
Warrenton, Virginia at 6:27am EST looking over Washington D.C.
Triple conjunction of Comet ISON, Mars, Regulus on October 14, 2013, as seen from Payson, Arizona, USA. Credit and copyright: Chris Schur.
This nice image comes from Chris Schur from Arizona, taken on October 14, and is also of the conjunction. “As you may recall, on this date of 10/14 the three objects were in a perfect line going from south to north in Leo,” Chris said via email. “What a spectacular sight in the 11 x 80 binoculars! While the comet was quite faint, a short 1/4 degree of tail could be seen, and the gorgeous blue and orange colors of the planets.”
Chris used a Canon Xti, ASA800 with 10 minutes total integration time, with a 80mm f/4.8 Ziess APO refractor on a Televue GEM. Taken from Payson, Arizona at 5,100 feet elevation.
Hubble's view of Comet ISON on Oct. 9, 2013. Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)
We’ve been showing images of Comet ISON from amateur astronomers around the world, but now that NASA is back from the government shutdown, here’s more proof that the comet is still intact and has not disintegrated … despite some predictions to the contrary. This image was taken on October 9.
NASA explains:
In this NASA Hubble Space Telescope image taken on October 9, the comet’s solid nucleus is unresolved because it is so small. If the nucleus broke apart then Hubble would have likely seen evidence for multiple fragments.
Moreover, the coma or head surrounding the comet’s nucleus is symmetric and smooth. This would probably not be the case if clusters of smaller fragments were flying along. What’s more, a polar jet of dust first seen in Hubble images taken in April is no longer visible and may have turned off.
This color composite image was assembled using two filters. The comet’s coma appears cyan, a greenish-blue color due to gas, while the tail is reddish due to dust streaming off the nucleus. The tail forms as dust particles are pushed away from the nucleus by the pressure of sunlight. The comet was inside Mars’ orbit and 177 million miles (284 million km) from Earth when photographed.
So, its not disintegrating, its not a three-piece body, its not a UFO… instead Comet ISON is turning out to be a rather average, ordinary comet. How has this comet sparked predictions that have gone from “bright as the full moon” to “disintegrating as we speak,” asked Josh Sokol from the Hubble ISON blog? “Simply put, ISON peaked early. When it was first discovered, way out past Jupiter, ISON was really bright,” Sokol wrote. “Extrapolated, those first data points made ISON look like it would shine even more as it got closer — and when it didn’t, the coverage seesawed back toward calling ISON a total bust.”
But ISON is still en route to the Sun. It will pass closest to the Sun on November 28, and if it remains intact after that close pass, it will make its closest approach to Earth on December 26, at a distance of 39.9 million miles (64 million km).
NASA is having a live Hangout with Hubble comet scientists to discuss the new image and latest research findings about ISON today (Oct. 17) at 4 p.m. EDT (20:00 UTC).
After last week’s non-episode, the Weekly Space Hangout roared back to life. We had big news on the Government Shutdown, the Earth flyby from the Juno spacecraft, and a big update on Comet ISON.
We also had a special guest, author and journalist Lee Billings, who was here to talk about his newest book, Five Billion Years of Solitude. Lee talked about his work on the book, and the state of extrasolar planet research in general.
Here was the team:
Host: Fraser Cain
Panel: Casey Dreier, Nancy Atkinson, Amy Shira Teitel, Jason Major, and David Dickinson
We broadcast the Weekly Space Hangout every Friday afternoon as a Google+ Hangout on Air. You can watch us live on Google+, or on YouTube, or right here on Universe Today. We start at 12:00 pm Pacific / 3:00 pm Eastern.
Comet ISON on October 8, 2013 as seen through the Schulman 0.8 Telescope atop Mount Lemmon at the University of Arizona SkyCenter. Credit: Adam Block/UA SkyCenter.
As we reported yesterday, the latest data on Comet ISON indicates there is some encouraging news as far as the Comet surviving perihelion, its closest approach to the Sun. While some are all doom and gloom about the potential for Comet ISON putting on a good show, these latest images indicate that as of now, this comet is alive and doing well!
“We really do not know what comet ISON is going to do when it gets near the Sun,” wrote astronomer Karl Battams of the Comet ISON Observing Campaign website. “But what we can say for certain, right now, is that comet ISON is doing just fine! It continues to behave like a fairly typical, if somewhat smaller-than-average, Oort Cloud comet. It has given no indication that it has fragmented and while such an event can never be ruled out, we see no evidence or hint that the comet is in any imminent danger of doing so. Any reports to the contrary are just speculation.”
You can read more from Battams about the current status of ISON, but just take a look at some of these gorgeous latest images from a variety of astrophotographers:
Comet ISON on October 9, 2013, an 18-minute exposure from 10:22 – 10:43 U.T.. Credit and copyright: John Chumack.Comet ISON (top) passing above Mars This is a stack of 5 x 5 minute exposures. Credit and copyright: Alan Dyer/Amazing Sky PhotographyComet ISON on October 7, 2013, imaged with a robotic iTelescope facility. Credit and copyright: Peter Lake.A 20-exposure stack of images from the 2-meter Liverpool Telescope. Credit and copyright: Ernesto Guido, Nick Howes and Martino Nicollini/Remanzacco Observatory.Comet ISON on October 4, 2013 as seen over Arizona, viewed with a 12.5″ telescope, over an hour exposure time. Credit and copyright: Chris Schur.
Keep checking Universe Today’s Flickr page for more additions and the latest shots from around the world. You can also keep tabs on Comet ISON from SpaceWeather.com’s Comet ISON Realtime Gallery. Better yet, try and see it for yourself! As of now, you’ll need to find someone with a fairly good telescope, so check out your local amateur astronomy club or observatory and find out when they are planning on viewing ISON. And if the comet can hold itself together, we’re all holding out hope that it will be visible with the naked eye after is passes by the Sun in late November. Here’s our detailed viewing guide from now until perihelion.
Comet ISON near to its close approach to Mars, imaged together from the 2 meter Liverpool Telescope. Credit: Remanzacco Observatory/Ernesto Guido, Nick Howes, and Martino Nicolini/NSO Liverpool Telescope.
Comet ISON made its closest approach to Mars yesterday (October 1, 2013) at a distance of 10.5 million km (6.5 million miles). While we await to find out if attempts to image the comet by spacecraft on the surface (update: those images are in — see them here) and in orbit of Mars were successful, astronomers from Earth were able to capture the two planetary bodies together.
You can see the two planetary bodies together in one image below from Ari Koutsouradis in Maryland, but the Remanzacco Observatory team obtained images of Comet ISON as it passed by Mars using the 2 meter Liverpool Telescope. This main image above consists of a stack of 20 exposures, 11 seconds each.
Ernesto Guido, Nick Howes and new team member Martino Nicolini produced this image, showing a “well developed coma and tail measuring at least 3 arc minutes,” the trio wrote on their website.
This image of Mars (lower right) and Comet ISON (upper left) was taken about 5:00 AM EDT in Westminster Maryland using a Nikon D5000 and a Stellarvue 80ED telescope. It’s composed of 44 30-second exposures at ISO1600, stacked using DeepSkyStacker. Credit and copyright: Ari Koutsouradis.
This image, directly above, taken early this morning by Ari Koutsouradis in Maryland, shows both Mars and the comet in one image, although it highlights the relative distance between the two. Koutsouradis said via Flickr that the comet was not visible with an eyepiece on the scope, but the image stack did manage to bring it out.
During the observations by the Remanzacco team, they wanted to look to see if they could discern additional jet structures on the comet, which had been reported by other observers. Howes told Universe Today, however, the are still looking at their observations to analyze this.
“There was some debate as to the existence of additional jet structures on the comet,” Howes said via email. “Our data analysis seems to show that some reports of this were possibly spurious, however, our one process does seem to show a possible small jet, which a 2m class instrument would be able to detect. Our analysis is undergoing additional review and peer checking with our collaborators in the USA. The scientific analysis of this comet and its inner coma is ongoing, and being monitored closely.”
Update: Later in the day on October 2nd, The Remanzacco team obtained analysis from their U.S collaboration partners. Using their data from the 2m Liverpool telescope, and after processing by Dr. Nalin Samarasinha of the Planetary Science Institute, they have conclusively confirmed a sunward facing feature on Comet ISON. A dust feature was detected by Nalin and Howes’ team in previous ISON observations —see one of our previous articles for more details — though they are not sure if this and the new jet feature are connected.
Using Samarasinha’s own modeling and processing algorithms, the PSI team validated the processing performed by the Remanzacco team which showed a small, but discernible forward-facing feature on the comet. Dr. Samarasinha, a world leading cometary scientist, believes this to be a real feature and not the result of processing artifacts, given the very good signal-to-noise of the data.
“As we said earlier, we suspected one of the processing routines we used showed a real feature, but wanted to be 100% sure with a peer review and further analysis,” said Guido, “and the PSI team has independently shown this.
Here is Dr. Samarasinha’s image processing, using his own division by azimuthal average process to the left, and the Remanzacco team’s MCM (median coma model) process image to the right. The pixel scale is 0.3″/pixel:
Additional analysis and processing shows a forward, Sun-facing feature on Comet ISON. Credit: Dr. Nalin Samarasinha of the Planetary Science Institute.
Howes added that their team will continue to monitor ISON as it approaches perihelion (closest approach to the Sun) on November 28.
“Our team has an ongoing programme of observations with a range of telescopes around the world,” he said, “including the iTelescope Network, the LT on La Palma and also with schools on the Faulkes Telescope, in support of two U.S observatory teams. The LT and iTelescope network is currently well placed to take these early observations as the comet approaches perihelion.”
If the comet survives its close pass by the Sun, it will pass closest to Earth on December 26, about 64 million km (40 million miles) away.
Meanwhile, even though NASA had to curtail many of its activities due to the government shutdown, many missions such as the Mars Reconnaissance Orbiter and the Mars Science Laboratory rover Curiosity were still up and running because they are run out of the Jet Propulsion Lab, which runs as a contractor to NASA, and are not government facilities. (JPL is privately run by the California Institute of Technology (Caltech), and the Applied Physics Lab, which operates the MESSENGER and New Horizons missions, is run by Johns Hopkins University, also a contractor to NASA. They’ll be able to operate as long as the money they have received from NASA previously holds out. (So, keep your fingers crossed for a short government shutdown.)
Therefore, imaging attempts by MRO and MSL of Comet ISON from Mars went ahead as scheduled, and we should be hearing how those attempts fared as soon as the images can be received back on Earth and processed. The word from the HiRISE camera team via Twitter is that they were able to image the comet. Stay tuned!
Three different views of Comet ISON’s inner coma. Credit: Remanzacco Observatory/Ernest Guido, Nick Howes and Martino Nicolini.
Here’s an enlargement of additional observations by the Remanzacco team, showing the inner coma of Comet ISON. Their explanation:
In the image (above) you can see 3 different elaborations of the ISON inner coma. The first panel on the left is a Larson-Sekanina filter. In the middle panel elaboration with the MCM filter creates an artificial coma, based on the photometry of the original image, and subtract the original image itself in order to highlight the internal zones of different brightness that are very close to the inner core and that would normally be hidden from the diffuse glow of the comet. While the last panel on the right is the elaboration with filter RWM – 1/r theoretical coma subtraction.
Comet ISON, photographed with a 3-inch (80mm) telescope on this morning Sept. 28 shows a circular green coma and short dust tail pointing northwest. Click to enlarge. Credit: Michael Jaeger
As NASA and the European Space Agency prepare their remote photojournalists – Mars Express, Mars Reconnaissance Orbiter and the Curiosity and Opportunity rovers – to capture photos of Comet ISON’s flyby of Mars early next week, amateur astronomers continue to monitor and photograph the comet from backyard observatories across the blue Earth. Several recent color photos show ISON’s bright head or nucleus at the center of a puffy, green coma. Green’s a good omen – a sign the comet’s getting more active as it enters the realm of the inner solar system and sun’s embrace.
Another great photo of the “greening” of Comet ISON taken on Sept. 24 with a 17-inch (43-cm) telescope. Click to enlarge. Credit: Damian Peach
Sunlight beating down on the comet’s nucleus (core) vaporizes dust-impregnated ice to form a cloud or coma, a temporary atmosphere of water vapor, dust, carbon dioxide, ammonia and other gases. Once liberated , the tenuous haze of comet stuff rapidly expands into a huge spherical cloud centered on the nucleus. Comas are typically hundreds of thousands of miles across but are so rarified you could wave your hand through one and not feel a thing. The Great Comet of 1811 sported one some 864,000 miles (1.4 million km) across, nearly the same diameter as the sun!
Among the materials released by solar heating are cyanogenand diatomic carbon. Both are colorless gases that fluoresce a delicious candy-apple green when excited by energetic ultraviolet light in sunlight.
Sounds like a plan. Newspaper clipping from 1910.
Cyanogen smells pleasantly of almonds, but it’s a poisonous gas composed of one atom each of carbon and nitrogen. Diatomic carbon or C2 is equally unpleasant. It’s a strong, corrosive acid found not only in comets but also created as a vapor in high-energy electric arcs. But nature has a way of taking the most unlikely things and fashioning them into something beautiful. If you’re concerned about the effects of cometary gas and dust on people, rest easy. They’re spread too thinly to touch us here on Earth. That didn’t stop swindlers from selling “comet pills” and gas masks to protect the public from poisoning during the 1910 return of Halley’s Comet. Earth passed through the tail for six hours on May 19 that year. Amazingly, those who took the pills survived … as did everyone else.
Comet ISON’s location and approximate appearance on October 1 seen from the Curiosity Rover. ISON will pass only 6.7 million miles (10.8 million km) from Mars on Tuesday Oct. 1. Stellarium
While Comet ISON is still too faint for visual observers to discern its Caribbean glow, that will change as it beelines for the sun and brightens. If you could somehow wish yourself to Mars in the next few days, I suspect you’d easily see the green coma through a telescope. The comet – a naked eye object at magnitude 2.5-3 – glows low in the northern sky from the Curiosity rover’s vantage point 4.5 degrees south of the Martian equator.
Comet Hale-Bopp shows off its bright dust tail and fainter, blue ion tail in early spring 1997. Credit: Bob King
I’ve noticed that when a comet reaches about 7th magnitude, the green coloration becomes apparent in 8-inch (20 cm) and larger telescopes. Bright naked eye comets often display multiple subtle colors that change chameleon-like over time. Dust tails, formed when sunlight pushes dust particles downwind from the coma, glow pale yellow. Gusty solar winds sweep back molecules from the coma into a second “ion” tail that glows pale blue from jazzed up carbon monoxide ions fluorescing in solar UV.
One of the highlights of seeing Comet L4 PANSTARRS through a small telescope was its brilliant, pea-like false nucleus glowing yellow from sunlit dust. The real comet nucleus – the actual comet – lies within the false nucleus and hidden by dust. Drawing: Bob King
During close encounters with the sun, millions of pounds of dust per day boil off a comet’s nucleus, forming a small, intensely bright, yellow-orange disk in the center of the coma called a false nucleus. Earlier this year, when Comet C/2011 L4 PANSTARRS emerged into the evening sky after perihelion, not only was its yellow tail apparent to binocular users but the brilliant false nucleus glowed a lovely shade of lemon in small telescopes.
With ISON diving much closer to the sun than L4 PANSTARRS, expect a full color palette in the coming weeks. While it may not be easy being green for Sesame Street’s Kermit the Frog, comets do it with aplomb.
Is it Friday already? Then it’s time for another Weekly Space Hangout. Join a team of dedicated space journalists to discuss the big space and astronomy news stories that broke this week. This time around, we discussed Amy Shira Teitel’s Buran article, ISON Watch 2013, and the re-re-discovery of water on Mars.
We record the Weekly Space Hangout every Friday at 12:00 pm Pacific / 3:00 pm Eastern, 2000 GMT. You can watch from here on Universe Today, or over on Google+ or YouTube.
Comet ISON, as seen on September 22, 2013 at 10:00 UTC (6:00 am EDT) from Yellow Springs, Ohio, using a QHY8 CCD camera and a home-made 16 inch diameter telescope. 15 minute exposure. Credit and copyright: John Chumack.
Perhaps you’ve read the news. This Fall, the big ticket show is the approach of Comet C/2012 S1 ISON. The passage of this comet into the inner solar system has been the most anticipated apparition of a comet since Hale-Bopp in 1997.
Many backyard observers will get their first good look at Comet ISON in the coming month. If you want to see this comet for yourself, here’s everything you’ll need to know!
A composite image of Comet ISON as seen from the Hubble Space Telescope on April 30th, 2013. (Credit: HubbleSite.org/Go/ISON).
Discovered on September 21st, 2012 by Artyom-Kislovodsk and Vitaly Nevsky using the International Scientific Optical Network’s (ISON) 0.4 metre reflector, this comet has just passed out from behind the Sun from our Earthly vantage point this summer to once again become visible in the dawn sky.
Of course, there’s much speculation as to whether this will be the “comet of the century” shining as “bright as the Full Moon” near perihelion. We caught up with veteran comet observer John Bortle earlier this year to see what skywatchers might expect from this comet in late 2013. We’ve also chronicled the online wackiness of comets past and present as ISON makes its way into the pantheon as the most recently fashionable scapegoat for “the end of the world of the week…”
But now it’s time to look at the astronomical prospects for observing Comet ISON, and what you can expect leading up to perihelion on November 28th.
Comet ISON as recently imaged by Efrain Morales on September 22nd. (Credit: Efrain Morales/Jaicoa Observatory, used with permission).
Advanced amateur astronomers are already getting good images of Comet ISON, which currently shines at around +12th magnitude in the constellation Cancer. And although NASA’s Deep Impact/EPOXI mission is down for the count, plans are afoot for the Curiosity rover and the Mars Reconnaissance Orbiter to attempt imaging the comet when it makes its closest approach to the Red Planet on October 1st at 0.0724 Astronomical Units (A.U.) or 10,830,000 kilometres distant. If MSL is successful, it would be the first time that a comet has been observed from the surface of another world.
Currently, ISON sits about a magnitude below the projected light curve, (see below) but that isn’t all that unusual for a comet. Already, there’s been increasing talk of “ISON being a dud,” but as Universe Today’s Nancy Atkinson pointed out in a recent post, these assertions are still premature. The big question is what ISON will do leading up to perihelion, and if it will survive its passage 1.1 million kilometres above the surface of the Sun on November 28th to become a fine comet in the dawn skies in the weeks leading up to Christmas.
ISON is already starting to show a short, spikey tail in amateur images. Tsutomu Seki estimated it to be shining at about magnitude +11.1 on September 16th. Keep in mind, a caveat is in order when talking about the magnitudes of comets. Unlike stars, which are essentially a point source, the brightness of a comet is spread out over a large surface area. Thus, a comet may appear visually fainter than the quoted magnitude, much like a diffuse nebula. Although +6th magnitude is usually the limit for naked eye visibility, I’ll bet that most folks won’t pick up ISON with the unaided eye from typical suburban sites until it breaks +4th magnitude or so.
The recent revised light curve projected for Comet ISON (Credit: NASA CIOC/Compiled by Matthew Knight of the Lowell Observatory).
The forward scattering of light also plays a key role in the predicted brightness of a comet. The November issue of Astronomy Magazine has a great article on this phenomenon. It’s interesting to note that ISON stacks up as a “9” on their accumulated point scale, right at the lower threshold of comet “greatness,” versus a 15 for sungrazing Comet C/1965 S1 Ikeya-Seki. Another famous “9” was Comet C/1996 B2 Hyakutake, which passed 0.1018 A.U. or 15.8 million kilometres from Earth on March 25, 1996.
ISON will pass 0.429 A.U. or 64.2 million kilometres from Earth the day after Christmas. Bruce Willis can stay home for this one.
Here is a blow-by-blow breakdown of some key dates to watch for as ISON makes its plunge into the inner solar system:
-September 25th: ISON crosses the border from the astronomical constellation of Cancer into Leo.
-September 27th: ISON passes 2 degrees north of the planet Mars.
The path of Comet ISON from October 1st to November 21st. The position of the Sun is shown on the final date. (Created by the Author using Starry Night Education software).
-October 1st: The 12% illuminated waning crescent Moon passes 10 degrees south of Mars & ISON.
-Early October: ISON may break +10th magnitude and become visible with binoculars or a small telescope.
-October 4th: New Moon occurs. The Moon then exits the dawn sky, making for two weeks of prime viewing.
–October 10th: ISON enters view of NASA’s STEREO/SECCHI HI-2A CAMERA:
-October 16th: ISON passes just 2 degrees NNE of the bright star Regulus, making a great “guidepost” to pin it down with binoculars.
-October 18th: The Full Moon occurs, after which the Moon enters the morning sky.
-October 26th: A great photo-op for astro-imagers occurs, as ISON passes within three degrees the Leo galaxy trio of M95, M96, & M105.
The position of Comet ISON on October 26th in Leo near Mars and a trio of galaxies. (Created by the author in Stellarium).
-October 30th: The 17% illuminated Moon passes 6 degrees south of ISON.
-Early November: Comet ISON may make its naked eye debut for observers based at dark sky sites.
-November 3rd: A hybrid (annular-total) solar eclipse occurs, spanning the Atlantic and Central Africa. It may just be possible for well placed observers to catch sight of ISON in the daytime during totality, depending on how quickly it brightens up. The Moon reaching New phase also means that the next two weeks will be prime view time for ISON at dawn.
-November 5th: ISON crosses the border from the astronomical constellation of Leo into Virgo.
-November 7th: ISON passes less than a degree from the +3.6 magnitude star Zavijava (Beta Virginis).
-November 8th: ISON passes through the equinoctial point in Virgo around 16:00 EDT/20:00 UT, passing into the southern celestial hemisphere and south of the ecliptic.
-November 14th: ISON passes less than a degree from the 10th magnitude galaxy NGC 4697.
-November 17th: The Moon reaches Full, passing into the morning sky.
-November 18th: ISON passes just 0.38 degrees north of the bright star Spica.
-November 22nd: ISON crosses into the astronomical constellation of Libra.
-November 23rd: ISON sits 4.7 degrees SSW of the planet Mercury and 4.9 SSW of Saturn, respectively.
Looking east before dawn on the morning of November 23rd. Note comet 2P/Encke nearby! (Created by the author using Starry Night Education software).
-November 25th: ISON pays a visit to another famous comet, passing just 1.2 degrees south of short period comet 2P/Encke which may shine at +8th magnitude.
-November 27th: ISON enters the field of view of SOHO’s LASCO C3 coronagraph.
-November 28th: ISON reaches perihelion at ~18:00 PM EST/ 23:00 UT.
After that, all bets are off. The days leading up to perihelion will be tense ones, as ISON then rounds the Sun on a date with astronomical destiny. Will it join the ranks of the great comets of the past? Will it stay intact, or shatter in a spectacular fashion? Watch this space for ISON updates… we’ll be back in late November with our post-perihelion guide!
It’s Friday so it’s space hangout time. Join Universe Today publisher Fraser Cain and a crew of space journalists as they discuss the big stories of the week. We’ve got the launch of the Antares rocket, a freaked out armadillo, an unexpected end to Deep Impact, ISON conspiracy madness, and more. We were joined by our regulars, but it was Elizabeth Howell’s first time. She’s been a long-time contributor to Universe Today, but this was the first time she’s joined the Weekly Space Hangout.
Host: Fraser Cain
Commentary: Amy Shira Teitel, David Dickinson, Elizabeth Howell, Jason Major
We record the Weekly Space Hangout every Friday afternoon at 12:00 Pacific, 3:00 Eastern, or 20:00 GMT. You can watch it live on Google+ or on Universe Today. You can also get the audio version within the 365 Days of Astronomy Podcast.
