Asteroid Will Safely Pass Earth in 2040

The entire universe in blog form
Dec. 22 2012 8:00 AM

Phew! One Less Asteroid Impact to Worry About

Asteroid 2001 AG5 as seen in October 2012 by the Gemini telescope.
Asteroid 2001 AG5 as seen in October 2012 by the Gemini telescope. A concern for a short time, we now know it will miss the Earth in 2040.

Image credit: Gemini Observatory

Yay! Asteroid 2011 AG5 will not hit us in 2040! Up until now, I couldn’t say that with perfect certainty.

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!  

Here’s the scoop: Last year, a 140-meter rock was discovered on an orbit that takes it very near the Earth. Projecting the orbit forward in time showed that it had a small but non-zero chance of impacting the Earth in the year 2040. That would be bad: It would explode upon impact with a yield of more than 100 megatons, far larger than even the biggest nuclear weapon ever detonated on Earth. While that wouldn’t cause a worldwide extinction event—this is no dinosaur-killer—an explosion equal to blowing up 100 million tons of TNT is something to be avoided.

Advertisement

The odds of impact were only about 1 in 500, but that’s still too high to rest easy. The problem is that initially, the asteroid’s orbit was difficult to determine well enough to predict where it would be more than a few years in the future. The analogy I like is pretending you’re an outfielder in a baseball game, and as soon as the batter hits the ball, you have to close your eyes. How do you know where the ball will be when it comes down? If you can only get a second to look at it after it’s hit, you only have a vague idea where it will land. But the longer you can track it, the more accurately you can see where it’s headed. Track it long enough and you can catch it.

It’s the same with asteroids. Earlier in 2012 only a few observations of AG5 could be made before it got too close to the Sun to see. Those allowed the crude estimate of where it would be in 2040, and that big fuzzy volume of space included the Earth.

Old and new orbital calculations for 2011 AG5.
Old (top) and new (bottom) orbital calculations for 2011 AG5. At first there was a small chance of Earth impact, but the new observations have eliminated that possibility.

Image credit: NASA/JPL/Paul Chodas

However, new observations taken with the monster Gemini telescope in Hawaii allowed a far better orbit to be calculated. The path of the asteroid in 2040 was found, and now clearly does not include the Earth. It will be a clean miss, by about 900,000 kilometers (550,000 miles). This is more than twice the distance to the Moon, if that helps.

The diagram above shows this: The upper picture shows the uncertainty in the region of space the asteroid would pass in 2040, and Earth is in that region. The lower picture shows the new calculations, with the asteroid missing us entirely.

I reported on this asteroid back in March 2012. At the time, with the impact risk of 0.2 percent, some people were concerned about AG5. One of those was Apollo 9 astronaut Rusty Schweickart, who is now with the B612 Foundation, a group dedicated to understanding and preventing asteroid impacts. He urged NASA to work on a plan to do something about the asteroid, should further observations make the odds for an impact higher.

Part of the problem at the time was that the asteroid was too close to the Sun to observe, and while there was a short window to observe in October 2012, it wouldn’t be until September 2013 that AG5 would be clear enough from the Sun to easily observe it. Schweickart didn’t want to lose a whole year should the asteroid prove dangerous.

Eventually NASA did perform an initial investigation into this, but now, happily, it won’t be needed. The October window worked out, the orbit refined, and now we know it’ll miss.

But this exercise was hardly a waste of time. The lessons learned were important. There are more asteroids out there, and given enough time the odds climb to certainty that we will be hit if we do nothing. The good news is we are looking for them, and hopefully, should we find one with our name on it, we’ll have enough time to be able to do something about it.

As for what we can do, stay tuned. I’ll have more about that shortly.

Tip o’ the Whipple shield to AsteroidWatch on Twitter.

TODAY IN SLATE

Politics

Meet the New Bosses

How the Republicans would run the Senate.

Even by Russian Standards, Moscow’s  Anti-War March Was Surprisingly Grim

I Wrote a Novel Envisioning a Nigerian Space Program. Then I Learned Nigeria Actually Has One.

Photos of the Crowds That Took Over NYC for the People’s Climate March

Friends Was the Last Purely Pleasurable Sitcom

The Eye

This Whimsical Driverless Car Imagines Transportation in 2059

Medical Examiner

Did America Get Fat by Drinking Diet Soda?  

A high-profile study points the finger at artificial sweeteners.

The Government Is Giving Millions of Dollars in Electric-Car Subsidies to the Wrong Drivers

A Futurama Writer on How the Vietnam War Shaped the Series

Trending News Channel
Sept. 20 2014 11:13 AM Watch Flashes of Lightning Created in a Lab  
  News & Politics
Politics
Sept. 22 2014 11:13 AM Your Own Personal Rand Paul How the libertarian hero makes his foreign policy contradictions disappear.
  Business
Moneybox
Sept. 22 2014 12:07 PM Divestment Isn’t the Answer To destroy demand for fossil fuels, universities can do a lot better than just selling some stocks.
  Life
Dear Prudence
Sept. 22 2014 12:00 PM Dear Prudence Live Chat For September 22, 2014.
  Double X
The XX Factor
Sept. 22 2014 12:21 PM Watch John Oliver Take on Miss America
  Slate Plus
Science
Sept. 22 2014 8:08 AM Slate Voice: “Why Is So Much Honey Clover Honey?” Mike Vuolo shares the story of your honey.
  Arts
Brow Beat
Sept. 22 2014 11:32 AM South Park Takes on Washington’s NFL Team and Its Terrible Name
  Technology
Future Tense
Sept. 22 2014 12:14 PM Family Court Rules That You Can Serve Someone With Legal Papers Over Facebook
  Health & Science
Science
Sept. 22 2014 12:15 PM The Changing Face of Climate Change Will the leaders of the People’s Climate March now lead the movement?
  Sports
Sports Nut
Sept. 18 2014 11:42 AM Grandmaster Clash One of the most amazing feats in chess history just happened, and no one noticed.