Comet ISON’s gone but positively not forgotten. The National Science Foundation today shared the results of their Comet ISON Photography Contest. You’ll recognize many of the names because so many of their photos have graced stories written for Universe Today.
Come take a look back at the high points of one of the most highly anticipated and studied comets of all time. Click each photo for a full-sized view. Congratulations to all the winners!
Hey, remember Comet C/2012 S1 ISON? Who can forget the roller-coaster ride that the touted “Comet of the Century” took us on last year. Well, ISON could have one more trick up its cosmic sleeve –although it’s a big maybe — in the form of a meteor shower or (more likely) a brief uptick in meteor activity this week.
In case you skipped 2012 and 2013, or you’re a time traveler who missed their temporal mark, we’ll fill you in on the story thus far.
Comet ISON was discovered by Artyom Novichonok and Vitali Nevski on September 21st, 2012 as part of the ongoing International Scientific Optical Network (ISON) survey. Shortly after its discovery, researchers knew they had spotted something special: a sungrazing comet already active at over 6.4 Astronomical Units (A.U.s) from the Sun. The Internet then did what it does best, and promptly ran with the story. There were no shortage of Comet ISON conspiracy theories for science writers to combat in 2013. It’s still amusing to this day to see predictions for comet ISON post-perihelion echo through calendars, almanacs and magazines compiled and sent to press before its demise.
The frenzy for all things ISON reached a crescendo on U.S. Thanksgiving Day November 28th 2013, as ISON passed just 1.1 million kilometres from the surface of the Sun. Unfortunately, what emerged was a sputtering ember of the comet formerly known as ISON, which faded from view just as it was slated to reenter the dawn sky.
Hey, we were crestfallen as well… we had our semi-secret dark sky site pre-selected for ISON imaging post-perihelion and everything. Despite heroic searches by ground and space-based assets, we’ve yet to see any compelling recoveries of Comet ISON post-perihelion.
This week, however, Comet ISON may put on its last hurrah, in the form of a minor meteor shower. We have to say from the outset that we’re highly skeptical that an “ISON-id meteor outburst” will grace the skies. Known annual showers are fickle enough, and it’s nearly impossible to predict just what might happen during a meteor shower with no past track record.
But you won’t see anything if you don’t try. If anything is set to occur, the night of January 15th into the 16th might just be the time to watch. This is because the Earth will cross the orbital plane of ISON’s path right around 9:00 PM EST/2:00 UT. Last year, ISON passed within 3.3 million kilometres of the Earth’s orbit on its inbound leg. Earlier last year, ISON was estimated to have been generating a prodigious amount of dust, at a rate of about 51,000 kilograms per minute. Any would-be fragments of ISON outbound would’ve passed closest to the Earth at 64 million kilometres distant on the day after Christmas last year. Veteran sky observer Bob King wrote about the prospects for catching ISON one last time during this month back in December 2013.
Another idea out there that is even more unlikely is the proposal that dust from Comet ISON may generate an uptick in noctilucent cloud activity. And already, a brief search of the internet sees local news reports attempting to tie every meteor observed to ISON this week, though no conclusive link to any observed fireball has been made.
The radiant to watch for any possible “ISON-ids” sits near the +3.5 magnitude star Eta Leonis in the sickle of Leo. Robert Lundsford of the American Meteor Society notes in a recent posting that any ISON-related meteors would pass through our atmosphere at a moderate 51 kilometres a second, with a visible duration of less than one second.
Note that meteor activity has another strike against it, as the Moon reaches Full on the same night. In fact, the Full Moon of Wednesday January 15th sits in the constellation Gemini,just 32 degrees away from the suspect radiant!
Another caveat is in order for any remaining dooms-dayers: no substantial fragments of ISON are (or ever were) inbound and headed towards our fair planet. Yes, we’re seeing rumblings to this effect in the pseudoscience netherworlds of ye ole Internet, along with ideas that ISON secretly survived, NASA “hid” ISON, ISON cloaked like a Romulan Bird of Prey, you name it. Just dust grains, folks… a good show perhaps, but nothing more.
As near as we can tell, talk of a possible meteor shower generated from Comet ISON goes all the way back to a NASA Science News article online from April 2013. Radio observers of meteor showers should be alert for a possible surge in activity this week as well, and it may be the case that more radio “pings” will be noted than visual activity what with the light-polluting Full Moon in the sky. The radiant for any would-be “ISON-ids” transits highest in the sky for northern hemisphere observers at around 2 AM local.
But despite what it has going against it, we’d be thrilled if ISON put on one last show anyhow. It’s always worth watching for meteor activity and noting the magnitude and from whence the meteor came to perhaps note the pedigree as to the shower it might belong to.
The next annual dependable meteor shower won’t be until the night of April 21st to the 22nd, when the Spring Lyrids are once again active. And this year may just offer a special treat on May 24th, when researchers have predicted that the Earth may encounter debris streams laid down by Comet 209P LINEAR way back in 1803 and 1924… Camelopardalids, anyone? Now, that’s an exotic name for a meteor shower that we’d love to see trending!
Is there any hope of detecting what’s left of Comet ISON after the sun proved too much for its delicate constitution? German amateur astronomer Uwe Pilz suggest there remains a possibility that a photographic search might turn up a vestige of the comet when Earth crosses its orbital plane on January 16, 2014.
Update: See an image below taken by Hisayoshi Kato of the comet’s location in Draco on December 29!
On and around that date, we’ll be staring straight across the sheet of debris left in the comet’s path. Whatever bits of dust and grit it left behind will be “visually compressed” and perhaps detectable in time exposure photos using wide-field telescopes. To understand why ISON would appear brighter, consider the bright band of the Milky Way. It stands apart from the helter-skelter scatter of stars for the same reason; when we look in its direction, we peer into the galaxy’s flattened disk where the stars are most concentrated. They stack up to create a brighter band slicing across the sky. Similarly, dust shed by Comet ISON will be “stacked up” from Earth’s perspective on the 16th.
This isn’t the first time a comet has leapt in brightness at an orbital plane crossing. You might recall that Comet C/2011 L4 PanSTARRS temporarily brightened and assumed a striking linear shape when Earth passed through its orbital plane on May 27.
Pilz, a longtime contributor to the online Comets Mailing List for dedicated comet observers,has made a series of simulations of Comet ISON for mid-January using his own comet tail program. He bases his calculations on presumed larger particle sizes 1 mm – 10 mm – not the more common 0.3-10 micrometer fragments normally shed by comets. The assumption here is that ISON has remained virtually invisible since perihelion because it broke up into a smaller number of larger-than-usual pieces that don’t reflect light nearly as efficiently as larger amounts of smaller dust particles.
The images look bizarre at first glance but totally make sense given the unique perspective. Notice that the debris stream becomes thinner as we approach orbital crossing; any potential dust blobs appear exactly edge-on similar to the way Saturn’s rings narrow to a “line” when Earth passes through the ring plane.
Besides the fact that not a single Earth-bound telescope has succeeded to date in photographing any of ISON’s debris, amateurs who attempt to fire one last volley the comet’s way will face one additional barrier – the moon. A full moon the same day as orbital crossing will make a difficult task that much more challenging. Digital photography can get around moonlight in many circumstances, but when it comes to the faintest of the faint, the last thing you want in your sky is the high-riding January moon. One night past full, a narrow window of darkness opens up and widens with each passing night.
Will anyone take up the challenge?
UPDATE Dec. 30 10 a.m. (CST): We may have our very first photo of Comet ISON from the ground! Astrophotographer Hisayoshi Kato made a deep image of the comet’s location in Draco on December 29 using a 180mm f/2.8 telephoto lens near the Mauna Loa Observatory in Hawaii at 11,000 feet. He stacked 5 exposures totaling 110 minutes to record what could be the ISON’s debris cloud. It’s incredibly diffuse and faint and about the same brightness as the Integrated Flux Nebula, dust clouds threading the galaxy that glow not by the light of a nearby star(s) but instead from the integrated flux of all the stars in the Milky Way. We’re talking as dim as it gets. What the photo recorded is only a tentative identification – followup observations are planned to confirm whether the object is real or an artifact from image processing. Stay tuned.
On December 18, the Hubble Space Telescope slewed to Comet ISON’s expected position and found nothing down to the incredibly faint magnitude of 25. According to astronomer Hal Weaver, who planned the ISON search, that limit implies any remaining fragments would have to be smaller than about 500 feet (160 meters) in diameter.
Nothing is visible in any of the images in the photo panel except trailed stars and galaxies, reflections and the occasional zap of a cosmic ray. After ISON was torn asunder by the sun, there existed the possibility that comet’s remains would follow a slightly different orbit. To make sure he was covered, Weaver photographed two separate comet positions, stacking several exposures together.
“The images have been combined so that features not at the same place in the various images are suppressed. Any comet fragments would show up more clearly in this composite, though stars still show up as faint streaks”, writes Zolt Lavay, author of the ISONblog at the Hubble site.
Again, nothing shows up in these either. While no one can say that ISON has completely disappeared, we now know that at the very least it’s broken into pieces too small for even Hubble to see. What was once a beautiful sight in binoculars has expanded into a vast cloud of gas and dust thinner than Ebenezer Scrooge’s gruel.
German company “Eclipse-Reisen” (Eclipse Travel) had to make a last-minute change in plans for a Dec. 8 flight for some 75 tourists planning to observe ISON, which morphed into a travelling dust blob after skimming too close to the sun in late November. Fortunately, Comet Lovejoy is still a strong astronomical object, providing an alternate thing to watch.
“Most of the passengers weren’t disappointed. They were more excited to see something new. Only a few journalists cancelled the flight. All photographers and experts fully understood the situation,” a statement from Air Partner to Universe Today said. (The spokespeople were German-speaking, requiring a translation by another party.)
“Comet Lovejoy is no less spectacular and still very exciting like ISON and they were pleased to see it, actually. Although Lovejoy is less bright than ISON, it is weaker by four size classes, its tail is smaller and pale and Lovejoy flies farther past the Earth and the Sun.”
The company had to ask for permission to alter its flight path, and inform the passengers of the last-minute change, all in a few days, but officials added that the flight went off without a hitch.
You can read more information about the company (in German) on its website. In 2014, it plans to run a flight to observe auroras over Iceland, among others.
Casey Lisse, also from CIOC was a bit more hopeful. In a web posting yesterday (Dec. 4) he said, “At this time, scientists are not sure how much of the comet survived intact. We may be seeing emission from rubble and debris in the comet’s trail, along its orbit, or we may be seeing the resumption of cometary activity from a sizable nucleus-sized chunk of ISON.”
Lisse added that most astronomers agree that Comet ISON was destroyed (with greater than 90% probability of this having occurred), leaving behind small (less than 10 m radius from the original 1 km nucleus) pieces of rubble, but there could be fragments 100 meters radius or larger. This would be big enough for astronomers to study but probably not big enough to provide a nice sky display later in December that everyone was hoping for.
Here’s the schedule of events for spacecraft to study whatever is left of Comet ISON, according to Lisse:
– NASA will monitor the comet for the next several weeks. If there is nothing sizable and stable left, it will dissipate and disappear in this time, as already emitted dust leaves the vicinity. If there is still a central source of emission, even if it is very much smaller, we will see a new, much fainter coma and tail form, which currently may be overwhelmed by the dust emitted from before the disruption event.
– NASA’s STEREO spacecraft will be using their cameras to search for bright fragments throughout the week, while the NASA Infrared Telescope Facility (IRTF) in Honolulu, Hawaii will use its 3m wide telescope to detect the comet spectroscopically, the same way it did on ISON’s inbound journey. Radio telescopes around the world will also be able to tell us more about what has happened. NASA’s recently launched MAVEN spacecraft may try to observe ISON next week. By mid- to late-December NASA’s Hubble and Chandra observatories will be performing deep outer space searches for any remnants of the comet. Spitzer will also look for ISON in early 2014.
If a fragment that acts like a comet is detected, but at a much reduced level, it may be hard to see it from the Earth at the time of its closest approach on December 26, 2013.
You can find out the latest on what is going on with ISON tomorrow, Dec. 6, 2013 as the CIOC is holding a post-perihelion workshop to discuss the status of the comet. The morning sessions, live from theh Applied Physics Lab at Johns Hopkins University will be webcast from approximately 8:30 am EST to 11:30 am EST, will be available for viewing in the player below:
More details on the meeting are available here.
So far, 12 spacecraft and the International Space Station have observed and detected Comet ISON on its multi-million year journey from the Oort Cloud to the solar corona. You can find out more about the planned Hubble observations here.
Astrophotographer Damian Peach has wowed us with his images of Comet ISON the past few months. Here’s a montage of some of his best images from September 24 to November 15.
“This may well be my final word on it.” Damian said via email, “but here it is growing in brightness on approach to its best in mid-late November.”
And while it appears there’s a ghost of ISON out there with a blob of dust in the latest views from the Sun-studying satellites, it won’t give us the views we had hoped for. But its been a fun experience the past few months, watching what unfolded. Thanks for bringing us along for the ride with your images, Damian!
Comets can spend billions of years out in the Oort Cloud, and then a few brief moments of terror orbiting the Sun. These are the sun grazers. Some survive their journey, and flare up to become the brightest comets in history. Others won’t survive their first, and only encounter with the Sun. Continue reading “Astronomy Cast 324: Sun Grazers”