Guide to Safely Viewing Comet ISON on Perihelion Day, November 28

The day of truth is fast approaching. Will Comet ISON’s sungrazing ways spark it to brilliance or break it to bits? How bright will the comet become? Studying the latest images from NASA’s STEREO Ahead sun-watching spacecraft, it’s obvious that ISON remains healthy and intact. The most recent pictures taken from the ground confirm that no major breakup has occurred. Assuming that ISON doesn’t crumble apart on Nov. 28, when it passes just 730,000 miles (1.2 million km) from the sun, it could brighten to -4 magnitude or better in the hours leading up to and after the moment of perihelion at 12:24:57 p.m. CST (18:24:57 UT).

This beautiful photo of Comet ISON was taken from a mountaintop observatory with a 300mm lens by Juan Carlos Casado of Spain on Nov. 24, 2013. Casado “stacked” or composited four photos to enhance the brightness of the comet against twilight. Click to enlarge.
This beautiful photo of Comet ISON was taken from a mountaintop observatory with a 300mm lens by Juan Carlos Casado of Spain on Nov. 24, 2013. Casado “stacked” or composited four photos to enhance the brightness of the comet against twilight. Click to enlarge.

For comparison, the planet Venus hovers around -4 magnitude and is routinely visible visible with the naked eye in broad daylight if you know exactly where to look. For the sake of establishing a baseline, let’s imagine that ISON will match Venus in magnitude during its crack-the-whip fling around the sun. Naturally, this would put the comet within range of naked eye visibility smack in the middle of the day. Well, maybe. ISON presents us with a little problem. While it may grow bright enough to view in daylight, it will be very close to the sun on perihelion day. Not only will it be difficult to tease from the solar glare, but with the sun only a degree or two away, there’s a real danger you could damage your eyes if you stray too close.

Comet ISON swings rapidly around the sun on perihelion day Nov. 28. Times shown are CST with north up and west to the right. Created with Chris Marriott's SkyMap software
Comet ISON swings rapidly around the sun on perihelion day Nov. 28.  Positions are shown hourly with north up and west to the right. Created with Chris Marriott’s SkyMap software

During the early morning hours of the 28th, ISON will lie approximately 2.5 degrees from the sun’s limb or edge. At the time of perihelion that separation narrows to less than 1/2 degree or one solar diameter.  This is likely when the comet will shine brightest, but with the sun so close, it will be next to impossible to spot it with naked eye or binoculars at that time. Matter of fact, don’t even try – it’s not worth the risk of damaging your retinas. An expert observer with a carefully-aimed telescope might pick it up, but must use extreme caution that sunlight not enter the field of view. Come sunset, the distance widens again to a somewhat more comfortable 2.5 degrees.

Once, when following Venus as a crescent through inferior conjunction, I dared track it within 2.5 degrees of the sun. THAT was almost too close for comfort. I had to avert my vision from a brilliant wedge of internally reflected sunlight along one side of the view and wear sunglasses to temper the brilliance of the “safe zone” where Venus appeared.. Red and polarizing filters can help reduce glare and increase contrast for near-sun viewing of comets and planets.

Comet McNaught on Jan. 13, 2007 photographed with a 500mm lens. "Comet was easily visible by naked eye," said photographer Mark Vornhusen of Gais, Switzerland. Click to enlarge
Comet McNaught on Jan. 13, 2007 photographed with a 500mm lens. “Comet was easily visible by naked eye,” said photographer Mark Vornhusen of Gais, Switzerland. Will ISON give us a similar show? Click to enlarge. Credit: Mark Vornhusen / Wikipedia

In mid-January 2007, Comet C/2006 P1 McNaught had a similar close brush with the sun and peaked around magnitude -5. For several days around perihelion on Jan. 12 it was plainly visible with the naked eye in broad daylight. I spotted it 5.6 degrees from the sun at magnitude  -3.5 (twice as faint as Venus) at 10 a.m. on Jan. 13 and 5 degrees from the sun the following day when I estimated its magnitude at -4.5. While close, 5 degrees is a much more comfortable distance for comet and inner planet viewing.

Example using a rooftop to block the sun so you can search near it for any sign of the comet. If using binoculars, BE SURE you focus them at infinity before daytime comet hunting otherwise there's no way to know if the comet will be in focus. I use clouds (the best) or a distant treeline. Credit: Bob King
Example using a rooftop to block the sun. When using binoculars for daytime comet hunting, BE SURE you focus them first at infinity otherwise there’s no way to know if the comet will be in focus. I use clouds (the best) or a distant treeline. Credit: Bob King

Whether naked eye, binocular or telescope, the favorite method for finding Comet McNaught in 2007 remains the best for Comet ISON in 2013. Block out the sun by placing something with a crisp edge in its way. Power poles, street lights (finally a good use for them), buildings, roof gables, church steeples and even clouds make ideal sun filters. They effectively remove the sun and allow you to look as close as is safe. Safety is critical here – never look directly at the sun. The damage to your retina will be swift and painless. No comet is worth losing your precious sense of sight.

As Earth rotates, the sun slowly moves across the sky. When using binoculars, if you start to see a bright reflection from approaching sunlight in the field of view, shift your position and re-cover the sun. I’ve been asked if  you can simply hold an appropriate solar filter over your eye to dim the sun. Yes you can, but the filter will also completely block your view of the much, much fainter comet. Use the filter instead to dim the sun so you can hunt nearby for the comet.

Use these little pictures to help you know in what direction from the sun to look for Comet ISON every 2 hours from 8 a.m. to 2 p.m. CST Thursday Nov. 28. Stellarium
Use these little pictures to help you know what direction from the sun to look for Comet ISON between 8 a.m. and 2 p.m. CST Thursday Nov. 28. Add one hour for Eastern time; subtract 1 hour for Mountain and 2 hours for Pacific. Be sure to face the direction shown when using the diagrams and completely block the sun from view.  Stellarium
Our final view shows the comet shortly before sunset in the southwestern sky when it lie about 2.5 degrees directly above the sun.
Our final view shows the comet shortly before sunset in the southwestern sky when it lie about 2-2.5 degrees directly above the sun. Time is 4 p.m. CST

 

Since ISON will be 2.5 degrees from the sun in the early morning and again just before sunset, those might be the best times to find it. Compared to the hour or two around perihelion, the glare will be less though ISON will likely be a little fainter.  You can use the diagram above, suitable for mid-northern latitudes, to know in what direction from the sun to look for the comet. If ISON becomes at least as bright as Venus and your sky is deep blue and haze-free, you might just see it on Thursday before sitting down to that Thanksgiving turkey dinner. But of course much depends upon the comet.

Comet ISON will be under constant view Nov. 27-30 in the SOHO coronagraph, an instrument that blocks the sun so scientists can study the near-solar environment. Click to see images. Credit: NASA/ESA
Comet ISON will be under constant view Nov. 27-30 in the SOHO coronagraph, an instrument that blocks the sun so scientists can study the near-solar environment. Click to see images. Credit: NASA/ESA

Don’t fret if it’s cloudy. Head over to the Solar and Heliospheric (SOHO) website. There you’ll have a ringside seat Nov. 27-30 as Comet ISON makes its death-defying turn around the sun. Thereafter it will appear risk-free in the morning sky with what we hope will be a beautiful tail.

Say Goodbye to Comet ISON (for now): Timelapse and Image Gallery

Comet ISON is heading towards its inexorable close pass of the Sun, which will occur on November 28, 2013. And while we’ve been enjoying great views from astrophotographers, that luxury is probably over as of today, as the comet is just getting to close to the Sun — and its blinding glare — for us to see it. But while we won’t be able to see it from Earth, we’re lucky to have a fleet of spacecraft that will be able to keep an eye on the comet for us! The STEREO spacecraft has already taken images of ISON hurtling towards the Sun; the Solar and Heliospheric Observatory (SOHO) will start observations on November 27. Then, the Solar Dynamics Observatory (SDO) will view the comet for a few hours during its closest approach to the Sun, and the X-Ray telescope on the Hinode spacecraft will view Comet ISON for about 55 minutes during perihelion.

Will Comet ISON survive its close pass and emerge brighter than ever? Only time will tell. You can keep track of what is going on with ISON here on Universe Today, as well as at NASA’s Comet ISON website, the Comet ISON Observing Campaign website, and there will be a special Hangout on Google+ during perihelion on Nov. 28.

Above is a gorgeous timelapse of ISON from the Teide observatory in the Canary Islands on Nov. 22nd, 2013. See more images and videos below.

Above is a screenshot from the live camera views from the Canada France Hawaii Telescope webcam. You can see a live view from their webcam any time at this link.

A montage of images of Comet ISON, taken from January-May and then September to late November. Credit and copyright: Efrain Morales/
A montage of images of Comet ISON, taken from January-May and then September to late November. Credit and copyright: Efrain Morales/
Comet ISON seen on November 22, 2013 from Corvalis, Oregon, USA. Manual alignment of 20 frames of 4 seconds each in Deep Sky Stacker. Credit and copyright: A Nartist on Flickr.
Comet ISON seen on November 22, 2013 from Corvalis, Oregon, USA. Manual alignment of 20 frames of 4 seconds each in Deep Sky Stacker. Credit and copyright: A Nartist on Flickr.
Comet ISON (C/2012 S1) in the morning twilight, above centre, with Mercury above the trees at left of frame. Taken from home in southern Alberta, November 21, 2013, using the 135mm lens at f/2.8 and Canon 5D MkII at ISO 1600 for stack of 5 x 4 second exposures, tracked with the iOptron SkyTracker, with the ground from one exposure to avoid blurring from the tracking motion. Credit and copyright: Alan Dyer/Amazing Sky Photography.
Comet ISON (C/2012 S1) in the morning twilight, above centre, with Mercury above the trees at left of frame. Taken from home in southern Alberta, November 21, 2013, using the 135mm lens at f/2.8 and Canon 5D MkII at ISO 1600 for stack of 5 x 4 second exposures, tracked with the iOptron SkyTracker, with the ground from one exposure to avoid blurring from the tracking motion. Credit and copyright: Alan Dyer/Amazing Sky Photography.
Comet C/2012 S1 (ISON) plus possible fragmentation or disconnect event on  Nov 21, 2013, taken from New Mexico. Credit and copyright: Joseph Brimacombe.
Comet C/2012 S1 (ISON) plus possible fragmentation or disconnect event on Nov 21, 2013, taken from New Mexico. Credit and copyright: Joseph Brimacombe.

A glimpse of ISON from the Netherlands on November 21, 2013. Credit and copyright: Fred Kamphues.
A glimpse of ISON from the Netherlands on November 21, 2013. Credit and copyright: Fred Kamphues.
Comet ISON and Spica together during Full Moon on November 18, 2013, seen from Payson, Arizona. Credit and copyright: Chris Schur.
Comet ISON and Spica together during Full Moon on November 18, 2013, seen from Payson, Arizona. Credit and copyright: Chris Schur.

Want to get your astrophoto featured on Universe Today? Join our Flickr group or send us your images by email (this means you’re giving us permission to post them). Please explain what’s in the picture, when you took it, the equipment you used, etc.

NASA’s STEREO Spacecraft Spots Comets ISON and Encke

As comets ISON and Encke continue toward their respective rendezvous with the Sun, they have now both been captured on camera by NASA’s solar-observing STEREO spacecraft. The image above, taken on Nov. 21 (UT) with STEREO-A’s high-resolution HI-1 camera, shows ISON as it enters the field of view from the left. Encke is at center, while the planets Mercury and Earth (labeled) are bright enough to cause vertical disruptions in the imaging sensors. (The Sun is off frame to the right.)

As cool as this image is, it gets even better: there’s a video version. Check it out below:

Animation of STEREO-A images acquired on Nov. 20-21 (Karl Battams/NASA/STEREO/CIOC)
Animation of STEREO-A images acquired on Nov. 20-21 (Karl Battams/NASA/STEREO/CIOC)

The dark “clouds” coming from the right are density enhancements in the solar wind, causing all the ripples in comet Encke’s tail. (Source)

The position of NASA's STEREO spacecraft relative to Earth and the Sun on Nov. 22
The position of NASA’s STEREO spacecraft relative to Earth and the Sun on Nov. 22

It’s fascinating to watch how the solar wind shapes and affects the tail of comet Encke… as ISON moves further into view, I’m sure we’ll see similar disruptions in its tail as well. (And look what STEREO-A saw happen to Encke’s tail back in 2007!)

Encke reached the perihelion of its 3.3-year-long orbit on Nov. 21; newcomer ISON will arrive at its on Nov. 28. While it seems to be holding together quite well in these STEREO images, what happens when it comes within 730,000 miles of the Sun next week is still anybody’s guess.

Read more: Whoa, Take a Look at Comet ISON Now!

Watch Live Webcast: Countdown to Comet ISON

We’re all watching what’s happening with Comet ISON, and today, November 21, 2013 Astronomy Magazine and Discover Magazine are hosting a “Countdown to Comet ISON” Google Hangout event, where the magazines’ expert editors will have all your comet questions answered. all the action starts at 20:00 UTC (3 pm EST). With ISON reaching its brightest this month, Astronomy Editor-in-Chief Dave Eicher, Discover Editor-at-Large Corey Powell and several others will discuss things like:

· When and where can you spot Comet ISON?

· How best to photograph the comet

· What scientists hope to learn from ISON

· Other amazing facts about comets across the ages

We’ll post the video feed here when it goes live, but can also watch (and RSVP) at the G+ event page.

If you miss it live, you can watch the replay above.

Get Out Your Comet Scorecards: Comet Nevski Now Visible With Binoculars

Is 2013 truly the “Year of the Comet?” Perhaps “Comets” might be a better term, as no less than five comets brighter than +10th magnitude grace the pre-dawn sky for northern hemisphere observers.

Comet C/2013 V3 Nevski has just brightened up 6 magnitudes — just over a 250-fold increase in brightness — and now sits at around magnitude +8.8. Comet Nevski was just recently discovered by Vitali Nevski using a 0.4 metre reflecting telescope 12 days ago on November 8th. If that name sounds familiar, it’s because Nevski discovered the comet from the Kislovodsk observatory located near Kislovodsk, Russia which is part of the International Scientific Optical Network survey which located comet ISON last year. In fact, there was some brief controversy early on in its discovery that Comet C/2012 S1 ISON should have had the moniker Comet Nevski-Novichonok.

At the time of discovery, Comet Nevski appeared to be nothing special: shining at magnitude +15.1, it was well below our +10 magnitude limit for consideration as “interesting,” and was projected to linger there for the duration of its passage through the inner solar system. About a dozen odd such comet discoveries crop up per year, most of which give astronomers a brief pause as the orbit and size of the comet become better known, only to discern that they’re most likely to be nothing extraordinary.

The orbit of comet Nevski, as seen during the closest approach to the Earth on December 21st. (Credit:  The Solar System Dynamics JPL Small-Body Database Browser).
The orbit of comet Nevski, as seen during the closest approach to the Earth on December 21st. (Credit: The Solar System Dynamics JPL Small-Body Database Browser).

Such was to be the case with Comet Nevski, until it suddenly flared up this past weekend.

Observer Gianluca Masi caught Comet Nevski in outburst, using a Celestron C14 remotely as part of the Virtual Telescope 2.0 project:

Comet Nevski captured on November 14th by
Comet Nevski captured on November 14th by Gianluca Masi. (Credit: The Virtual Telescope 2.0 Project).

You’ll note that Comet Nevski shows a small, spiky tail on the brief exposure. As of this writing, it currently sits at between magnitudes +8 and +9 and should remain there for the coming week if this current outburst holds.

Comet Nevski is well placed for northern hemisphere observers high in the morning sky, and will spend the remainder of November and early December crossing the astronomical constellation of Leo.

The celestial path of Comet Nevski from mid-November to the end of December. (Created by the author using Starry Night Education simulation software).
The celestial path of Comet Nevski from mid-November to the end of December. (Created by the author using Starry Night Education simulation software).

Here’s a blow-by-blow rundown on noteworthy events for this comet for the remainder of 2013:

November 23rd: Passes the +5.3 magnitude star Psi Leonis and crosses north of the ecliptic plane.

December 1st: Passes +3.4 magnitude star Eta Leonis.

December 6th: Passes +4.8 magnitude 40 Leonis and the bright +2nd magnitude star Algieba.

December 15th: Crosses into the constellation Leo Minor.

December 17th: Passes near the +5.5th magnitude star 40 Leonis Minoris.

December 21st: Passes closest to Earth, at 0.847 Astronomical Units (A.U.s), or 126 million kilometres distant.

December 30th: Passes into the constellation Ursae Majoris.

Note that a “close pass” denotes a passage of the comet within a degree of a bright or interesting object.

The orbit of Comet Nevski is inclined 31.5 degrees relative to the ecliptic, and it will be headed for circumpolar for observers based in high northern latitudes as it dips back down below our “interesting” threshold of magnitude +10 in early 2014.

This comet passed perihelion on October 27th, 2013 just over a week prior to discovery. Comet Nevski is Halley-type comet, with a 27.5 year orbit.

So, looking at the “Comet Scorecard,” we currently have:

Comet C/2012 X1 LINEAR: Still undergoing a moderate outburst at magnitude +8.2, very low to the north east for northern hemisphere observers at dawn in the constellation Boötes.

Comet 2P/Encke: Reaches perihelion tomorrow at 0.33 AU’s from the Sun, shining at magnitude +7.7 near Mercury in the dawn sky but is now mostly lost in the Sun’s glare.

Comet C/2013 R1 Lovejoy: is currently well placed in the constellation Ursa Major crossing into Canes Venatici in the hours before dawn. Currently shining at magnitude +5.4, Comet R1 Lovejoy is visible to the unaided eye from a dark sky site. We caught sight of the comet last week with binoculars, looking like an unresolved globular cluster as it passed through the constellations of Leo and Leo Minor.

And of course, Comet C/2012 S1 ISON: As of this writing, ISON is performing up to expectations as it approaches Mercury low in the dawn shining at just above +4th magnitude. We’ve seen some stunning pictures as of late as ISON unfurls its tail, and now the eyes of the astronomical community will turn towards the main act: perihelion on November 28th. Will it fizzle or dazzle? More to come next week!

The recent outbursts of Comets X1 LINEAR and V3 Nevski are reminiscent of the major outburst of Comet Holmes back in 2007. Of course, the inevitable attempts to link these outbursts to the current sputtering solar max will ensue, but to our knowledge, no conclusive correlations exist. Remember, the outburst from Comet Holmes occurred as we were approaching what was to become a profound solar minimum.

Also, it might be tempting to imagine that all of these comets are somehow related, but they are in fact each on unique and very different orbits, and only appear in the rough general direction in the sky as seen from our Earthly vantage point… a boon for dawn patrol sky watchers!

Got pics? Send ‘em in to Universe Today!

 

 

Comet ISON Grows Wings; Comet Lovejoy, a Fountain

Wonderful photos of Comets ISON and Lovejoy with their swollen comas and developing tails  have appeared on these pages, but recently, amateur and professional astronomers have probed deeper to discover fascinating dust structures emanating from their very cores. Most comets possess a fuzzy, starlike pseudo-nucleus glowing near the center of the coma. Hidden within this minute luminous cocoon of haze and gas lies the true comet nucleus, a dark, icy body  that typically spans from a few to 10 kilometers wide. Comet ISON’s nucleus could be as large as several kilometers and hefty enough (we hope!) to survive its close call with the sun on Nov. 28.

Sketch using Photoshop of the inner region of Comet Lovejoy's coma showing the false nucleus and the curious dust fountain observed on Nov. 13 in a 15-inch (37-cm) telescope. Credit: Bob King. The dust fountain or plume captured on Nov. 12 next to the false nucleus deep within the coma of Comet Lovejoy. Credit: Luc Arnold
Sketch using Photoshop of the inner region of Comet Lovejoy’s coma showing the false nucleus and the curious dust fountain observed on Nov. 13 in a 15-inch (37-cm) telescope. Credit: Bob King. At right the same plume photographed on Nov. 12 with north up and east to the left. Credit: Luc Arnold

Last Wednesday morning Nov. 13 when calm air allowed a sharp view inside Comet Lovejoy’s large, 15-arc-minute-wide coma I noticed something odd about the false nucleus at low magnification, so I upped the power to 287x for a closer look. Extending from the fuzzy core in the sunward direction was a small cone or fountain-shaped structure of denser, brighter dust shaped like a miniature comet. It stretched eastward from the center and wrapped slightly to the south. Usually it’s harder than heck to see any details within the fuzzy, low-contrast environment of a comet’s coma unless that comet is close to Earth and actively spewing dust and ice. Lovejoy scored on both.

Negative image taken Nov. 14 of Lovejoy's nucleus and dust fan. Credit: Dr. P. Clay Sherrod
Negative image taken Nov. 14 of Lovejoy’s nucleus and dust fan. North up, west to the right. Credit: Dr. P. Clay Sherrod

By good fortune, Dr. P. Clay Sherrod of the Arkansas Sky Observatories, USA, and Luc Arnold of Saint-Michel-l’Observatoire, France, shared images they’d made at high magnification of the identical feature right at the same time as my own observation. There’s no doubt that what we saw was a jet or combined jets of dust and vapor blasting from Lovejoy’s true nucleus. Jets are linear or fan-shaped features and carry ice, dust and even snowballs from inside the nucleus out into space. They typically form where freshly-exposed ice from breaks or fissures in the comet’s crust vaporizes in the sun’s heat.

What I wouldn’t give to see one up close. Wait – we can. Take a look at the photo of Comet 103P/Hartley made during NASA’s EPOXI flyby mission in November 2010. Notice that most of Hartley’s crust appears intact with the jets being the main contributors to the dust and gas that form the coma and tail.

Multiple jets were actively spewing ice and dust when NASA's EPOXI mission zoomed by Comet Hartley 2  in November 2010. Credit: NASA
Multiple jets were actively spewing ice and dust when NASA’s EPOXI mission zoomed by Comet Hartley 2 in November 2010. The fuzzy spots are balls of fluffy snowballs measuring between 1 inch and 1 foot across. Credit: NASA

Spotting a jet usually requires good seeing (low atmospheric turbulence) and high magnification. They’re low-contrast features but worth searching for in any bright comet. Jets often point toward the sun for good reason – the sunward side of the comet is where the heating is happening. Activity dies back as the comet rotates to face away from the sun during the night and early morning hours. By studying the material streaming away from a comet via jets, astronomers can determine the rotation period of the nucleus.

Nightly images of Comet Hale-Bopp made March 24-30, 1997 by Brad D. Wallis of the Cassini imaging team at JPL. The photos were assembled into this animation by Sky & Telescope
Nightly images of Comet Hale-Bopp’s rotating nucleus and spiraling jet made March 24-30, 1997 by Brad D. Wallis of JPL. The photos were assembled into this animation by Sky & Telescope

Sometimes material sprayed by jets expands into a curved parabolic hood within the coma. This may explain the wing-shaped structures poking out from Comet ISON’s coma seen in recent photos. Possibly the Nov. 13-14 outburst released a great deal of fresh dust that’s now being pushed back toward the tail by the ever-increasing pressure of sunlight as the comet approaches perihelion.

The inner coma of Comet Hale-Bopp developed a striking series of hoods in March 1997 when a dust jet spewed material night after night from the comet’s rotating nucleus. The animation captures garden sprinkler effect beautifully. Since the nucleus spun around every 11 hours 46 minutes, multiple spiraling waves passed through the coma in the sunward direction. To the delight of amateur astronomers at the time, they were plainly visible through the telescope.

Processed images showing a possible jet next to Comet ISON' nucleus as well as the new wing-like coma structures on Nov. 17, 2013.  The jet's position angle or PA is 150 degrees or southeast of the nucleus. Credit: Denis Buczynski and Nick James
Processed images showing a possible jet extending southeast (PA 150 degrees) of Comet ISON’s nucleus as well as the new wing-like hoods on Nov. 17, 2013.  Credit: Denis Buczynski and Nick James of the BAA

When examining a comet, I start at low magnification and note coma shape, compactness and color as well as tail form and length and details like the presence of streamers or knots. Then I crank up the power and carefully study the area around the nucleus. Surprises may await your careful gaze. If Comet ISON does break up, the first sign of it happening might be an elongation or stretching of the false nucleus. If it’s no longer a small, star-like disk or if you notice a fainter, second nucleus tailward of the main, the comet’s days may be numbered.

Symmetrical "wings" photographed branching from Comet ISON's coma on Nov. 15. At right, the photo has been specially processed to show the structure more clearly. Credit: Erik Bryssinck
Another view of the symmetrical “wings” photographed branching from Comet ISON’s coma on Nov. 15. At right, the photo has been specially processed to show the structure more clearly. Credit: Erik Bryssinck

 

Whoa. Take a Look at Comet ISON Now

Let the show begin! With all our reports and images of Comet ISON being in outburst, this latest image from astrophotographer Damian Peach shows just how much activity is taking place in this comet as it races towards the Sun. “Hard to believe this is the same comet in my last image of Nov 10th!” Damian said via email.

ISON’s tail is suddenly full of streamers and features not seen before in this comet. At less than two weeks to its close encounter with the Sun on November 28, only a short amount of time will tell us if Comet ISON is just beginning to show off its brightness or if it is beginning to break apart.

The views here are through good quality telescopes. It is just now becoming visible to the naked eye, looking like a faint smudge at about magnitude +5.5.

Below is a “negative” view from Damain Peach, as well as a variety of views from Joseph Brimacombe and others that are coming in:

A widefield view of Comet ISON, taken from New Mexico Skies at 11h 59m UT on Nov. 15, 2013 using an FSQ 106 ED telescope and STL11K camera on a PME II mount. 1 x 10 min exposures. Credit and copyright: Joseph Brimacombe.
A widefield view of Comet ISON, taken from New Mexico Skies at 11h 59m UT on Nov. 15, 2013 using an FSQ 106 ED telescope and STL11K camera on a PME II mount. 1 x 10 min exposures. Credit and copyright: Joseph Brimacombe.
A narrowfield, false color view of Comet ISON on Nov. 15, 2013, taken from New Mexico. Credit and copyright: Joseph Brimacombe.
A narrowfield, false color view of Comet ISON on Nov. 15, 2013, taken from New Mexico. Credit and copyright: Joseph Brimacombe.

And an animation from Brimacombe:

A negative image of Comet ISON on Nov. 15, 2013, 106mm F5.0 with STL-11k. LRGB. L: 5x2mins. RGB: 1x2mins. Credit and copyright: Damian Peach.
A negative image of Comet ISON on Nov. 15, 2013, 106mm F5.0 with STL-11k. LRGB. L: 5x2mins. RGB: 1x2mins. Credit and copyright: Damian Peach.
Another view of Comet ISON this morning (Nov. 15) photographed by Leonid Elenin
Another view of Comet ISON this morning (Nov. 15) photographed by Leonid Elenin
Spectacular photo of Comet ISON taken this morning Nov. 15 from Charleston, Rhode Island, USA showing the recent outburst. Click to enlarge. Credit: Scott MacNeill
Spectacular photo of Comet ISON taken this morning Nov. 15 from Charleston, Rhode Island, USA showing the recent outburst. Click to enlarge. Credit: Scott MacNeill

Check out a simulator of how ISON will look in the skies from Earth or see this map of how to see ISON for yourself:

If you haven't seen the comet yet, you can use this map to track it through the weekend as it zips quickly through Virgo. The map shows the sky facing southeast just before the start of morning twilight or about 100 minutes before sunrise. ISON should be plainly visible in binoculars in a dark sky. Created with Chris Marriott's SkyMap program
If you haven’t seen the comet yet, you can use this map to track it through the weekend as it zips quickly through Virgo. The map shows the sky facing southeast just before the start of morning twilight or about 100 minutes before sunrise. ISON should be plainly visible in binoculars in a dark sky. Created with Chris Marriott’s SkyMap program

And for comparison, here is Damian Peach’s previous image from Nov. 10:

Comet ISON on Nov. 10 before the recent outburst with well-developed dust (upper) and gas tails. Click ot enlarge. Credit: Damian Peach
Comet ISON on Nov. 10 before the recent outburst with well-developed dust (upper) and gas tails. Click ot enlarge. Credit: Damian Peach

See Comet ISON Fly through Earth’s Sky with this Awesome Interactive Simulator

Here’s a handy tool. The folks at INOVE Space Models have just updated their awesome Comet ISON flyby simulation with a second point of view – how it looks from Earth. The first version let us watch from afar as ISON dives across across the solar system until it makes a hard left at the sun and returns to deep space. The new view lets you watch it track across the sky across from any location on Earth. Go to the link and toggle the Switch to Earth option in the upper left of the display and you’re off. The website attempts to automatically pinpoint where you are, but for me it was a tad off, selecting a town about 75 miles away. But a few miles this way or that make little difference given how far the comet is from Earth. If you need to make an adjustment, click the Location icon (upper right) and select your latitude and longitude.

Comet ISON on perihelion day (Nov. 28) seen from the Upper Midwest, U.S. The sun and comet will be in Scorpius. Credit: INOVE
Simulation of Comet ISON at noon CST on perihelion day (Nov. 28) seen from the Upper Midwest, U.S.A. The sun and comet will be in Scorpius. Credit: INOVE

You have two options for viewing. If you click the single arrow play button at the bottom of the screen, the display shows a horizon line with the stars, sun and comet rising and setting over a single day. In a day’s time the comet moves only a small distance in the sky, so it will appear in nearly the same spot the next day. Except around perihelion on Nov. 28. Then it moves so quickly – over 800,000 mph (1.3 million km) – fast enough to watch move hour by hour.

Besides just being plain cool to watch, the simulator is truly useful. The background star field shows constellation outlines and stars down to about 5th magnitude. Assuming the comet is reasonably bright, say 5th magnitude or brighter, you can use the simulations as locator maps now through the end of January. By clicking on the Time Box at upper right, you can set it to any time you like, grab a frame and head outside for a look.

Spectacular photo of Comet ISON taken this morning Nov. 15 from Charleston, Rhode Island, USA showing the recent outburst. Click to enlarge. Credit: Scott MacNeill
Spectacular photo of Comet ISON taken this morning Nov. 15 from Charleston, Rhode Island, USA showing the recent outburst. Click to enlarge. Credit: Scott MacNeill

Pressing the double arrow fast-forward button shows changes in position one day after another. To know what day you’re on just consult the timeline at the bottom of your screen. You can manually pull the time arrow to speed up, slow down or select a particular time of month. Other refinements are available in the Options box at upper left. Should you tire with Comet ISON from an earthly perspective, just click on Switch to Space at upper left and you’ll zoom back out for a solar system perspective. Enjoy the journey!

Another view of Comet ISON this morning photographed by Leonid Elenin
Another view of Comet ISON this morning photographed by Leonid Elenin

The un-simulated Comet ISON underwent a powerful outburst on Nov. 14 brightening by two magnitudes, as the two images here from Leonid Elenin and Scott MacNeil attest (and you can see more in our article from yesterday)

What had been a faint object in binoculars has become much more impressive. I caught it in my 10x50s in some small cracks between the clouds this morning (Nov. 15) and estimated its magnitude at 5.0. Had it been clear, I would have seen it with the naked eye. Through a 15-inch (37 cm) telescope at 64x  the coma, now twice its pre-outburst diameter, glowed more blue than green with a dense core that looked like a bright, fuzzy star. Frankly, ISON was beautiful. Let’s hope this little outburst leads to better things to come and not early signs of the comet’s dissolution. Take a look yourself at the next opportunity and there might be a surprise waiting for you.

Comet ISON Suddenly Brightens as it Dives Toward the Sun

After a sleepy week, Comet ISON is suddenly coming alive. Several amateur astronomers and at least one professional astronomers are reporting today that the comet has brightened at least a full magnitude overnight.  Two days ago it glowed at around magnitude 7.5 and was visible weakly in 10×50 binoculars from a dark sky. Now it’s surged to around magnitude 5.5 – just above the naked eye limit – and continues to brighten. Several amateur astronomers have even seen it without optical aid.

Comet ISON on Nov. 10 before the recent outburst with well-developed dust (upper) and gas tails. Click ot enlarge. Credit: Damian Peach
Comet ISON on Nov. 10 before the recent outburst with well-developed dust (upper) and gas tails. Click ot enlarge. Credit: Damian Peach

ISON’s appearance has radically changed too. A week ago the comet developed a second gas or ion tail streaming alongside the wider, brighter dust tail. That new appendage has since grown like Pinocchio’s nose to nearly equal the length of the dust tail. I spotted it with averted vision Tuesday morning Nov. 12 through a 15-inch (37 cm) telescope. More exciting, the ISON’s head has been much brighter and more compact. Astronomers rate a comet’s degree of condensation or “DC” on a scale of 0 to 9 from extremely diffuse with no brightening in the center to disk-like or stellar. In recent days, Comet ISON has been packing it in at DC=6 or moderately compact and bright. Now amateurs are reporting that the comet’s head has brightened and become much more compact with a DC of 8.

Comet ISON in outburst with a completely changed tail appearance and bright, very compact coma shot this morning. Credit: Juanjo Gonzalez
Comet ISON in outburst with a completely changed tail appearance and bright, very compact coma shot this morning. Gonzalez reports the comet at magnitude 6.4. Click to enlarge. Credit: Juanjo Gonzalez
You can watch Comet ISON evolve right before your eyes in this panel of photos taken by Juanjo Gonzalez. Top  row left-right: Nov. 3 and Nov. 9. Bottom row left right: Nov. 12 and Nov. 14. The tail structure changes are dramatic. Click to enlarge. Credit: Juanjo Gonzalez
You can watch Comet ISON evolve right before your eyes in this panel of photos taken by Juanjo Gonzalez. Top row left-right: Nov. 3 and Nov. 9. Bottom row left right: Nov. 12 and Nov. 14. The tail structure changes are dramatic. Click to enlarge. Credit: Juanjo Gonzalez

Backing up reports of the outburst, astronomer Emmanuel Jehin of the TRAPPIST (TRAnsiting Planets and PlanetesImals Small Telescope) team, noted a tenfold increase in dust production around the comet’s nucleus on Nov. 11 and 12  plus additional jets of material blasting into the coma.   Jehin reports that the inner coma near the nucleus is still very sharp and shows no sign of disruption – so far, ISON’s hanging in there.

If you haven't seen the comet yet, you can use this map to track it through the weekend as it zips quickly through Virgo. The map shows the sky facing southeast just before the start of morning twilight or about 100 minutes before sunrise. ISON should be plainly visible in binoculars in a dark sky. Created with Chris Marriott's SkyMap program
If you haven’t seen the comet yet, you can use this map to track it through the weekend as it zips quickly through Virgo. The map shows the sky facing southeast just before the start of morning twilight or about 100 minutes before sunrise. ISON should be plainly visible in binoculars in a dark sky. Created with Chris Marriott’s SkyMap program

This is all great news for comet observers. The intense heat of the sun is beginning to boil away the comet’s ice with greater fury. The heat may also be exposing new cracks or breaks in ISON’s crust. Fresh ice means even more material becomes available for the sun to vaporize and likely additional jumps in brightness in the next day or two.

Trouble finding  Virgo? Use this wide-view map to get oriented. Slide from Mars toward Spica near the southeastern horizon. ISON is about halfway between Spica and Gamma Virginis. The map shows the sky around 5-5:30 a.m. CST. Stellarium
Trouble finding Virgo? Use this wide-view map to get oriented. Slide from Mars toward Spica near the southeastern horizon. ISON is about halfway between Spica and Gamma Virginis. The map shows the sky around 5-5:30 a.m. CST. Stellarium

Comets Encke and ISON Spotted from Mercury

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 image of ISON from Nov. 10 (enlarged detail)
MESSENGER image of ISON from Nov. 10 (enlarged detail)

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.

Read more: Will Comet ISON Survive Perihelion?

“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.”

Comet 2P/Encke on October 30, 2013. The coma is partially obscuring the small barred spiral galaxy NGC 4371. Credit and copyright: Damian Peach.
Comet 2P/Encke photographed on October 30 by  Damian Peach.

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. (Source)

Read more: How to See This Season’s “Other” Comet: 2P/Encke

“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.

“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.”

– Ron Vervack, JHUAPL

Read more about the MESSENGER cometary observation campaign in the full news release here.

Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington/Southwest Research Institute