Frequently Asked Questions for Asteroid 2012 DA14 and Its Close Approach
by Bruce Betts
In summary, what is 2012 DA14, and how big is it?
2012 DA14 is an approximately 45 meter diameter (about half a football field) asteroid that will have a very close flyby of Earth on Feb. 15, 2013. Such a close flyby of this large an object has not happened in recent history. Though not visible with just your eyes, it will be visible with binoculars and telescopes, though challenging due to its speed across the sky. Discovery by La Sagra Observatory in Spain was made possible by a Shoemaker NEO grant from The Planetary Society.
Will the asteroid hit Earth in 2013?
No, there is no chance of it hitting Earth in 2013.
Will it hit Earth in the future?
Not in the next few decades, but there are small chances that it will hit after that including a 1 in 7.5 million chance of hitting in 2110.
IF it hit Earth in the future, how big would the impact be?
The energy equivalent would be about that of a 2 to 3 megaton nuclear weapon (nearly 200 times the energy release at Hiroshima). It would be comparable to the Tunguska impact in 1908 that leveled 2000 square kilometers of forest in Siberia. It could destroy a city if it happened to hit one.
How often do objects this size hit Earth?
On average, approximately every 1000 years. But, that could be tomorrow or 2,000 years from now.
Who discovered it and what made it possible?
La Sagra Observatory in Spain discovered it on Feb. 23, 2012. The discovery was made possible by a camera provided through the Planetary Society Shoemaker Near Earth Object (NEO) grant program that allowed detection of a fast moving object missed by the professional surveys. La Sagra has discovered more than 10 NEOs since installing the new camera in 2011. The discovery of 2012 DA14 last year will enable numerous observations this year to define its orbit better and to better understand the asteroid. You can read a blog about the discovery from one of the La Sagra observers, Jaime Nomen, as well as find discovery images there. You can hear a 2012 interview with Jaime Nomen on Planetary Radio, and you can hear a new interview coming out Feb. 4, 2013.
The Close Approach and Visibility
What is the time of closest approach
Feb. 15, 2013, 19:25 UT (11:25 PST)
What is the closest approach altitude?
Approximate altitude above the surface of the Earth will be 27,330 km, 17,000 mi (34,100 km, 21,200 mi from center of Earth). That is closer than the altitude of geosynchronous satellites, e.g., satellite TV satellites, at 35,786 km (22,236 mi) altitude. The flyby is shown in the following JPL produced diagram and you can compare its distance to both the Moon’s orbit and the orbits of geosynchronous satellites.
Could it hit a geosynchronous or other satellite?
The asteroid will not hit a geosynchronous satellite (satellites that are in an orbit allowing them to stay above the same point on Earth all the time) because it is coming inside that ring of satellites, and because those satellites are in equatorial orbits whereas the asteroid will come in at an angle so only spend a brief moment crossing the plane. Nearly all other satellites, e.g., the International Space Station, are much, much lower than the asteroid flyby distance so are safe.
Will it be visible with the naked eye, how bright will it be?
It will not be a naked eye object. At closest approach, its brightness will be about a magnitude of 7. It will be bright enough that it could be seen with steady binoculars or a small telescope if you are on the side of Earth it will be passing.
What parts of Earth will have a chance to observe it telescopically?
Near closest approach when it is brightest, most of Europe, Asia, and Africa. It will pass from the southern hemisphere to northern hemisphere. Though it will be much dimmer, it is observable by larger telescopes for days to weeks before and after closest approach.
Are big telescopes going to be looking at the asteroid?
Yes, including radar observations that will be particularly good at defining its size and its exact orbit.
How fast will it be moving across the sky?
At closest approach, almost 1 degree (2 Moon diameters) per minute. That is about 1/8 the speed of the International Space Station moving across the sky, but much, much faster than any “normal” astronomical object, making it a challenging object to track near closest approach for many telescopes.
Will astronauts on the International Space Station have a great view?
Not really. The ISS orbits only about 400 km above Earth so they are only a tiny bit closer to the flyby compared to the surface of the Earth, though they don’t have atmosphere in the way.
What is the orbit of 2012 DA14 like?
It is very similar to Earth’s orbit as you can see in these diagrams (created using the JPL small body database browser at http://ssd.jpl.nasa.gov/) . The first shows its orbit from above the plane of the solar system. The second is nearly edge on to the Earth’s orbit and allows you to see that the asteroid’s orbit is inclined about 10 degrees relative to Earth’s orbit. Both show the relative positions on Dec. 1, 2012. The orbit will be modified by the close pass to Earth, shortening its orbital period from 368 days to 317 days.
This asteroid won't hit Earth, at least for many, many decades. But it is a reminder we live in a cosmic shooting gallery. We need to find, track, and characterize these objects and develop the technical and political capability to deflect an asteroid. It is not a matter of whether there will be a dangerous impact, it is a matter of when. The Planetary Society and its members are working to do our part through programs like our Shoemaker NEO Grants, like the one that made the discovery of 2012 DA14 possible, and projects like Laser Bees, exploring new ways to potentially deflect a dangerous asteroid. Help prevent the only preventable natural disaster.
The excitement is building! LightSail is counting down to our test launch, set for May 20—and you’re invited.