Hubble captures picture of asteroid collision!

The entire universe in blog form
Feb. 2 2010 10:12 AM

Hubble captures picture of asteroid collision!

Last week, the Lincoln Near-Earth Asteroid Research (LINEAR) sky survey program, designed to sweep the heavens looking for near-Earth asteroids, spotted something really weird; an elongated streak that looked as if two asteroids had collided. Just days later, Hubble was pointed at the object, and what it saw was really really weird:


Phil Plait Phil Plait

Phil Plait writes Slate’s Bad Astronomy blog and is an astronomer, public speaker, science evangelizer, and author of Death From the Skies!  


[Click to armageddonate.]

This is a false-color image showing the object, called P/2010 A2, in visible light. The long tail of debris is obvious; this is probably dust being blown back by the solar wind, similar to the way a comet's tail is blown back. What apparently has happened is that two small, previously-undiscovered asteroids collided, impacting with a speed of at least 5 km/sec (and possibly faster). The energy in such a collision is like setting off a nuclear bomb, or actually many nuclear bombs! The asteroids shattered, and much of the debris expanded outward as pulverized dust.


Phew. OK, I feel better. I needed to get that off my chest.

First off, to be clear we're in no danger from this event. It was really far away (in human terms; 140 million km or 90 million miles -- the object's orbit keeps it farther from the Sun than Mars -- so we're not about to get pummeled with debris. And while the explosion energy was quite large -- certainly much larger than any weapon ever detonated on Earth -- it wasn't radioactive, in case you're worried about that sort of thing. This was a kinetic explosion, caused by a high-speed collision, and not an actual detonation of any kind.

Looking at the image, the bright spot to the left is most likely what's left of one of the two asteroids, a chunk of rock estimated to be a mere 140 meters (450 feet) across. In the press release they're not clear about the curved line emanating to the right of the nucleus. It may be -- and I'm spitballing here -- dust blown back from a stream of chunks, since the tail is broad and appears to originate from that swept curve, and not from the nucleus itself. The other filament perpendicular to the curve is from yet another piece of debris.

Despite how much this looks like a comet, ground-based observations indicate no gas is present, meaning this was from asteroids colliding, not comets, which have significant amounts of ice which turn to gas near the Sun. The collision energy was high enough to produce a lot of gas if any were present. That clinches this being an asteroid impact.

Also, the orbit of the object indicates it's an asteroid, and it appears to be part of a well-known group of asteroids called the Flora family, which share similar orbital characteristics, and are probably remnants themselves of an ancient breakup of a much larger parent asteroid.

Nothing like this has ever been seen before. Sure, Hubble and about a hundred other telescopes observed the comet Shoemaker-Levy 9 slam in to Jupiter in 1994, but that was different than seeing two asteroids hit. Asteroids are small, and very very far apart on average (don't believe scenes like that in "Empire Strikes Back"), so a collision like this is extremely rare, and catching it from such a great vantage point rarer still. But we have a lot of eyes on the sky, and the more we watch the more we'll see.

And we'd better. An object 140 meters across hitting the Earth would, to be technical, suck. Hard. Whatever caused Meteor Crater in Arizona, an impact scar over a kilometer across, was itself probably about 40 meters across. An object like 2010 A2, which is three times the diameter, would have 20 -30 times the mass, and do considerably more damage. I'm glad groups like LINEAR are out there patrolling the skies for such things. We need to learn as much as we can about these asteroids, so that we can prevent the next Meteor Crater from occurring.



Don’t Worry, Obama Isn’t Sending U.S. Troops to Fight ISIS

But the next president might. 

The Extraordinary Amicus Brief That Attempts to Explain the Wu-Tang Clan to the Supreme Court Justices

Amazon Is Officially a Gadget Company. Here Are Its Six New Devices.

The Human Need to Find Connections in Everything

It’s the source of creativity and delusions. It can harm us more than it helps us.

How Much Should You Loathe NFL Commissioner Roger Goodell?

Here are the facts.

Altered State

The Plight of the Pre-Legalization Marijuana Offender

What should happen to weed users and dealers busted before the stuff was legal?

Surprise! The Women Hired to Fix the NFL Think the NFL Is Just Great.

You Shouldn’t Spank Anyone but Your Consensual Sex Partner

Sept. 17 2014 5:10 PM The Most Awkward Scenario in Which a Man Can Hold a Door for a Woman
  News & Politics
Altered State
Sept. 17 2014 11:51 PM The Plight of the Pre-Legalization Marijuana Offender What should happen to weed users and dealers busted before the stuff was legal?
Business Insider
Sept. 17 2014 1:36 PM Nate Silver Versus Princeton Professor: Who Has the Right Models?
Sept. 17 2014 6:53 PM LGBTQ Luminaries Honored With MacArthur “Genius” Fellowships
  Double X
The XX Factor
Sept. 17 2014 6:14 PM Today in Gender Gaps: Biking
  Slate Plus
Slate Fare
Sept. 17 2014 9:37 AM Is Slate Too Liberal?  A members-only open thread.
Brow Beat
Sept. 17 2014 8:25 PM A New Song and Music Video From Angel Olsen, Indie’s Next Big Thing
Future Tense
Sept. 17 2014 9:00 PM Amazon Is Now a Gadget Company
  Health & Science
Medical Examiner
Sept. 17 2014 11:48 PM Spanking Is Great for Sex Which is why it’s grotesque for parenting.
Sports Nut
Sept. 17 2014 3:51 PM NFL Jerk Watch: Roger Goodell How much should you loathe the pro football commissioner?