Wednesday, July 27, 2011

Earth's First Asteroid Companion Discovered

This is an amazing discovery. Up until now, companion asteroids that more or less share an orbit with Earth have been theoretical. This class of asteroids is known as Trojans; Jupiter has them, and so do Mars and Neptune. Now Earth joins the club with 2010 TK7, an asteroid approximately 300 meters (1000 feet) across and 80 million km (50 million miles) from Earth.

Asteroid 2010 TK7 is circled in green, in this single frame taken by NASA's Wide-field Infrared Survey Explorer, or WISE. Image credit: NASA/JPL-Caltech/UCLA

NASA’s Wide-field Infrared Survey Explorer (WISE) managed to notice the small asteroid. WISE sees in the infrared, where warmer objects are easier to spot. 2010 TK7 is probably about the freezing point of water, which is pretty warm to astronomers. It also orbits such that it is mostly in the sky during daylight hours from Earth, so your typical amateur astronomer isn't going to be able to go out and spot this.

WISE was an asteroid hunting satellite that stopped operating back in February. Astronomers discovered 2010 TK7 by looking through the vast amount of data collected by WISE and confirmed it with Earth-based telescopes. This gives hope that other Earth Trojans might be buried in the data waiting to be found. Where there is one, there may be many.

What makes a Trojan, a companion asteroid, special, is that they orbit what is called a Lagrangian point. Five special spots between two astronomical bodies where gravity is essentially neutral. The points remain stable relative to where the one body is along its orbit around the other. The graph above maps out the locations of where these points would be.

2010 TK7 orbits Earth's L4 point, rather than remaining stable at the point or orbiting the Earth itself. It also has a kind of funky orbit that takes it closer and further away from the Earth, but it is still roughly 60 degrees in front of us and of no danger to the Earth. It just won't ever get close enough.
This artist's concept (not to scale) illustrates the first known Earth Trojan asteroid, discovered by WISE. The asteroid is gray and its extreme orbit is shown in green. Image credit: Paul Wiegert, University of Western Ontario, Canada

It is a tantalizing discovery because it opens the door to several new questions. We know little about this asteroid. It may be a candidate for future exploration, but because of it's odd orbit (it goes well above and below the orbital plane), it would be difficult to reach. But you can bet astronomers are going race to find more Earth Trojans. They have been looking for them for some time already, so it was only a matter of time.

And being an object of some importance, it will also need to be named. Coeus or Crius, the Titan sons of Gaia have been mentioned, but there are other sons of hers. Personally I wouldn't my the cyclopes sons of Gaia; Brontes ("thunderer"), Steropes ("lightning") and the "bright" Arges. But I guess we'll have to see.


22 comments:

Zombie said...

What an amazing discovery! :)

-E- said...

nice to see Lagrangians on the blogosphere.

Bonjour Tristesse said...

That is an amazing discovery, and its crazy seeing its orbit in the last image.

Jay said...

How about just "Asteroid", kinda like how our moon is just "Moon". ;)

The Dawg said...

Wow, that's really amazing.

Banacek said...

What the hell kind of orbit is that? And when they run out of names from Greco-Roman mythology, then what?

Astronomy Pirate said...

That wouldn't work Jay because they are likely to find more. And Banacek, they use names from other mythologies, including Japanese, Hawaiian, and whatever else. A lot are also named after people, usually their discoverers or in honor of somebody. But the vast majority of asteroids are just numbers.

Aaron M. Gipson said...

I am very curious as to why we have never noticed this object before now. It's extremely close to us, and we've been using decent telescopes for at least the last 500 years (you can correct me on that if I'm wrong). Are scientists entertaining the possibility that this object might be a remnant from the formation of the Moon?

Astronomy Pirate said...

Some great questions Aaron. Part of the reason we haven't noticed it before is exactly because of it being so close. trying to see something small close up is harder than seeing it from a further distance. Imagine a fly buzzing around your head, almost impossible to see; but a fly over on the wall is much easier to spot. As mentioned, the asteroid pretty much stays only in the daylight when viewed from Earth, making it that much harder to spot. It is also small and probably dark and rocky, so it really needed something much better than the decent telescopes from the last 500 years. It took a high tech infrared space telescope of the last decade to discover it.

As far as its origins, it is way to early to tell. I suspect that is something researchers are reeling over right now. But, given it's orbit, I would doubt it. I think lunar debris would for the most part be much more in line with the Earth/Moon orbital plane. The asteroid just appears to wander eccentrically.

Admin said...

That's pretty incredible.

Atley said...

I think it is a cool discovery... but I dont understand the significance? so the astroid orbits the sun in the same ammount of time we do? so.... what does that mean? anything? like can we use it as a base to launch from to reach other space places? or what? just dont understand why this matters. not trying to be a downer, just don't understand.

Major.Mack said...

yeah, that is amazing

Astronomy Pirate said...

Atley, the main significance that has been mentioned has been mining. It isn't the easiest of tasks to mine it though, but easier than the Moon. There are probably easier to reach near Earth asteroids too.

Another significance from my point of view is that if it formed where it is located at now and not captured, then it could hold key information on the origins of the Earth. If it formed from the Moon collision as Aaron put forth, it would build a better frame work on that event. We really have no clue of the significance right now, that's why it is important to study it in thorough detail.

Gryt said...

Gotta love asteroid buddies, what kind of resources could we mine out of an asteroid?

ScottD said...

Crazy orbit there!

Astronomy Pirate said...

Gryt, it depends on the asteroid, but everything ranging from silicates to titanium to helium to iridium, they are rich in all forms of rocky and metallic resources.

tracirz said...

Wow, awesome news! Thanks for sharing! :D

tracirz said...

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Sub-Radar-Mike said...

Really interesting discovery... I know my vote doesn't count but Brontes is a seriously awesome name. I also like your fly analogy up there in response to Aaron.

Phil S. said...

Am I the only one that can barely keep up with these things? You need to add a paragraph at the bottom with crayola drawings and text that a 3rd grader could understand. :D

Sorry. I'm trying to understand what is going on cosmically. Oh yeah, they better pick Brontes.

Electric Addict said...

cool post that's crazy stuff!

Shutterbug said...

The universe never fails to amaze me! :D

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