Comet ISON glows green in a picture captured by California astrophotographer Mike Hankey early Thursday. "This may be the last telescope photo of ISON I take before it goes around the sun," he writes.
Comet ISON is quickly growing in brightness as this month's climactic encounter with the sun approaches — but if you're looking for a cosmic spectacle, the best place to start is online.
The comet, formally known as C/2012 S1, was discovered a little more than a year ago. Even then, astronomers recognized that it had the potential to become the "comet of the century," owing to the fact that it was due to come well within a million miles (1.6 million kilometers) of the sun. If comets survive that kind of close encounter, they can become dramatically brighter — as Comet Lovejoy did in 2011.
Comet ISON has now become potentially visible to the naked eye. It makes an appearance an hour or two before sunrise in eastern skies, just above the bright star Spica in Virgo. This online finder chart from Sky & Telescope helps you locate ISON, as well as Comet Lovejoy and the planet Mercury.
We should emphasize the word "potentially," because each day brings ISON closer to getting lost in the glare of the dawning sun and the setting full moon. You'll need clear, dark skies and lots of patience to convince yourself that you've seen the comet's fuzzy glow.
If we're lucky, Comet ISON will survive its slingshot move around the sun on Thanksgiving Day, Nov. 28, and emerge as a spectacular sight for the Christmas season. When ISON was first discovered, there was talk that it might get as bright as the moon — which would arguably rank as the cometary sight of the century. In comparison, Lovejoy's brightness at its peak was merely close to that of Venus.
There's still a chance that ISON will fizzle out, either before or during the solar swing-by. While we wait to see which way things will go, skilled astrophotographers with tricked-out telescopes are turning out jaw-dropping pictures of ISON.
The best place to catch the show is SpaceWeather.com, which offers a huge gallery of comet pictures from amateurs around the world. One of my favorites, from California photographer Mike Hankey, shows multiple streamers emanating from ISON's greenish coma.
"What a surprise it was to image ISON this morning," Hankey wrote on Thursday. "I immediately noticed a significant brightness. I only had about 20 minutes of image time due to the sun rising and ISON's current low elevation. This may be the last telescope photo of ISON I take before it goes around the sun."
You can also get comet updates via the Space Telescope Science Institute's ISONblog and the Comet ISON Observing Campaign's website. On Twitter, follow @ISONUpdates, @CometISONnews, @CometISON2013 and @SungrazerComets. Check out the Vimeo time-lapse videos from Roy Spencer, Justin Ng and Randy Halverson. Heck, even NASA's Messenger probe has snapped pictures of ISON and Comet Encke from its orbit around Mercury.
If you're inspired to buy some equipment for your own heavy-duty ISON watch, this Space.com observing guide will point you in the right direction. But the Slooh virtual observatory is offering a cheaper way to get in on the real-time view. Just tune in its webcast at midnight Sunday, via Slooh's website, its iPad app, YouTube or this embedded window.
Slooh's host for the event, Paul Cox, will show live telescopic images from Slooh's observatory in the Canary Islands while he discusses the current state of the comet — and speculates on the possible outcomes of the Thanksgiving encounter. The ISON watch is the nightcap for a Slooh double feature also highlighting the Leonid meteor shower, which hits its peak this weekend. Stay tuned for more about the Leonids on Friday.
If you have an ISON picture you'd like to share, please feel free to drop it into our FirstPerson hopper for photogenic sky highlights — or post it to the NBC News Science Facebook page. We'll be watching online for your stellar snapshots.
More about Comet ISON:
Alan Boyle is NBCNews.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. To keep up with Cosmic Log as well as NBCNews.com's other stories about science and space, sign up for the Tech & Science newsletter, delivered to your email in-box every weekday. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.
First published November 14 2013, 5:19 PM