Because NASA’s twin STEREO probes are designed to observe the sun, they can see sundiving comets even when the glare becomes intense. Yesterday, Comet ISON joined Earth, Mercury, and Comet Encke in the field of view of STEREO-A’s Heliospheric Imager. Click on the image to view ISON’s grand entrance:
“The dark ‘clouds’ of stuff you see coming from the right are density enhancements in the solar wind, and these are what are causing all the ripples you see in comet Encke’s tail,” explains Karl Battams of NASA’s Comet ISON Observing Campaign. “I can pretty much promise you that we’re going to see ISON’s tail doing that in a couple of day’s time, but on a much larger scale!”
Battams points out another exciting development: Comet Encke and Comet ISON are converging for a photogenic close encounter. “No they’re not going to hit each other – in reality they are millions of miles apart – but as seen from the STEREO-A spacecraft, they are going to get very close!” he says. “We are probably a couple of days away from seeing two comets almost side-by-side in that camera, with long tails flowing behind them in the solar wind. To say that such an image will be unprecedented is rather an understatement.” Stay tuned for that.
Skywatchers excited as Comet ISON approaches its big day in the sun
As Comet ISON approaches its climactic Thanksgiving swing around the sun, astronomers are getting increasingly excited about the prospects for a memorable show when it comes around the other side.
“It’s looking pretty wonderful, to be honest,” Naval Research Laboratory astrophysicist Karl Battams, who’s part of the NASA Comet ISON Observing Campaign, told NBC News. “It’s behaving in terms of its brightness pretty much how we thought it would back in February.”
Comet ISON has been sparking stellar expectations ever since its discovery by Russian astronomers in September 2012. But unlike some comet fans, Battams has shied away from predicting it would turn into the “comet of the century.” Instead, he favors the saying attributed to veteran comet hunter David Levy: “Comets are like cats; they have tails, and they do precisely what they want.”
So far, Comet ISON appears to be doing what Battams and his colleagues want: It’s hanging together, and not breaking up as feared. Fresh imagery from NASA’s STEREO-A probe shows the comet in one piece — with Comet Encke’s tail waving in the solar wind as it approaches its own close encounter.
“There are some really, really nice tail dynamics going on,” Battams said.
Even as he gushes over the latest pictures, Battams is keeping that catlike unpredictability of comets in mind — particularly considering that ISON is due to come within only 700,000 miles (1.1 million kilometers) of the sun on Nov. 28. “My opinion this morning is, I’m starting to feel like it’s going to survive,” Battams said on Friday. “It might actually make it.”
If ISON does survive, “I’m feeling comfortable saying that we’re going to have a nice night-sky object in December,” he said.
How nice? “It was never going to be the ‘comet of the century,'” Battams said. “It’d have to be pretty good to out-comet Comet McNaught.”
Comet Lovejoy (formally designated C/2011 W3), which wowed Southern Hemisphere observers in 2011, might be a “good analog” if ISON lives up to Battams’ expectations. “It’s an educated guess,” he said.
ISON is on the verge of being too close to the sun for casual observers to make out in dawn’s skies, but seasoned skywatchers are still getting some good shots, as evidenced by the pictures submitted to SpaceWeather.com’s comet gallery.