Cosmic daredevil comet ISON will pass sun this week

Professional astronomers are eagerly awaiting the comet's much-anticipated brush with the sun, expected for Thanksgiving Day.

Cameron McCarty/NASA/MSFC/MEO
Comet ISON shines brightly in this image taken on the morning of Nov. 19, 2013. This is a 10-second exposure taken with the Marshall Space Flight Center 20" telescope in New Mexico.

The promising Comet ISON's close pass by the sun this week has amateur astronomers on the edge of their seats, but professional scientists are anticipating the celestial encounter with perhaps even greater relish.

Comet ISON is set to skim just 730,000 miles (1.2 million kilometers) above the surface of the sun on Thanksgiving Day (Nov. 28). The comet has brightened considerably as it has zoomed closer and closer to the sun in recent weeks, thrilling stargazers who have captured amazing photos of ISON and giving researchers interested in comet composition a lot to look forward to in the coming days.

"We're going to see primitive solar system material outgassing and sublimating when it's right close to the sun," said Karl Battams of the U.S. Naval Research Lab in Washington, D.C., who studies "sungrazing" comets like ISON. "So that right there gives us a huge chunk of valuable information." [How to See Comet ISON in the Night Sky]

A pristine sungrazer 

It's not particularly rare for a comet to zip close to the sun, or even dive straight through our star's sizzling-hot atmosphere. But Comet ISON is special, researchers say.

For starters, Comet ISON is bigger than most other sungrazers, with a core estimated to be about 1,650 feet (500 meters) wide, Battams said. Further, Comet ISON is likely making its first trip through the inner solar system from the distant, frigid comet repository known as the Oort Cloud. So its volatile components have not been baked off already by previous encounters with the sun, giving scientists a rare look at a relatively pristine comet.

"You have the primitive solar system material in a sungrazing orbit — that's something that is basically unprecedented in modern recorded history," Battams told "I'm sure it's happened before, but we have no definite record of a sungrazing Oort Cloud comet."

In addition, ISON was discovered back in September 2012, giving researchers lots of time to prepare for its solar flyby. They've thus been able to track the comet's journey with a variety of instruments on the ground and in space as part of the NASA-organized Comet ISON Observation Campaign (CIOC).

"We see sungrazing comets all the time, but they're always very small, and usually we get to see them maybe for a few hours in spacecraft data," said Battams, who is a member of the CIOC team. "In this case, with ISON, we've had well over a year of observing a sungrazing comet. So that helps us build up a picture of its behavior before it becomes a sungrazer, and then we can compare that to its behavior after it has done the sungrazing thing, assuming it survives."

Learning about the sun 

Sungrazing comets like ISON also give researchers a chance to learn more about our star. For example, scientists can measure the speed and other characteristics of the solar wind by noticing how the comet's tail behaves while it's still relatively far from the sun.

And as ISON dives past the sun on Thursday, a trail of its particles will cling to the magnetic field in the sun's atmosphere, opening a window on the processes occurring in this extreme environment.

"That helps us learn about some of the velocities of things that are going on there, the temperatures. We get to actually visibly see the magnetic field structure," Battams said. "It's a completely unique probe of that region of the solar system."

Like skywatchers, Battams and other researchers hope Comet ISON survives its Thanksgiving sun encounter. Just as ISON will put on its most dramatic sky show after the close encounter — if it survives — some of the best scientific observations will likely be made as the comet is zipping back out into the depths of space.

But the success of the observation campaign doesn't hinge on ISON's ability to hold together, Battams said.

"Even if the comet was to fizzle out right now … we could absolutely stand up and say that this whole observing campaign has just been an overwhelming success," he said. "We have so much data for the comet. So many resources, so many eyes, so many telescopes that have been pointed towards it for such a long time now have seen it go through so many morphological changes. We have a huge amount of data, really an unprecedented amount."

Editor's note: If you snap an amazing picture of Comet ISON or any other night sky view that you'd like to share for a possible story or image gallery, send photos, comments and your name and location to managing editor Tariq Malik at

You can follow the latest Comet ISON news, photos and video on

Follow Mike Wall on Twitter @michaeldwall and Google+. Follow us @Spacedotcom, Facebook or Google+. Originally published on

Copyright 2013, a TechMediaNetwork company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

You've read  of  free articles. Subscribe to continue.
Real news can be honest, hopeful, credible, constructive.
What is the Monitor difference? Tackling the tough headlines – with humanity. Listening to sources – with respect. Seeing the story that others are missing by reporting what so often gets overlooked: the values that connect us. That’s Monitor reporting – news that changes how you see the world.

Dear Reader,

About a year ago, I happened upon this statement about the Monitor in the Harvard Business Review – under the charming heading of “do things that don’t interest you”:

“Many things that end up” being meaningful, writes social scientist Joseph Grenny, “have come from conference workshops, articles, or online videos that began as a chore and ended with an insight. My work in Kenya, for example, was heavily influenced by a Christian Science Monitor article I had forced myself to read 10 years earlier. Sometimes, we call things ‘boring’ simply because they lie outside the box we are currently in.”

If you were to come up with a punchline to a joke about the Monitor, that would probably be it. We’re seen as being global, fair, insightful, and perhaps a bit too earnest. We’re the bran muffin of journalism.

But you know what? We change lives. And I’m going to argue that we change lives precisely because we force open that too-small box that most human beings think they live in.

The Monitor is a peculiar little publication that’s hard for the world to figure out. We’re run by a church, but we’re not only for church members and we’re not about converting people. We’re known as being fair even as the world becomes as polarized as at any time since the newspaper’s founding in 1908.

We have a mission beyond circulation, we want to bridge divides. We’re about kicking down the door of thought everywhere and saying, “You are bigger and more capable than you realize. And we can prove it.”

If you’re looking for bran muffin journalism, you can subscribe to the Monitor for $15. You’ll get the Monitor Weekly magazine, the Monitor Daily email, and unlimited access to

QR Code to Cosmic daredevil comet ISON will pass sun this week
Read this article in
QR Code to Subscription page
Start your subscription today