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Astronomers spot Earth’s first Trojan orbital partner

trojan2.JPG The Earth has a very skittish dance partner. Locked ahead of the Earth’s orbit lies a 300-metre lump of rock — Earth’s first Trojan asteroid, astronomers report today in Nature.

The points 60 degrees ahead of and behind a planet are one type of Lagrange point — stable gravitational wells where objects can lurk, caught between the Sun’s gravity and the planet’s. Objects residing in these spots are known as Trojans. With the discovery, the Earth joins Mars, Neptune and Jupiter as planets with known Trojans.

Trojans around Earth have been difficult to find because the objects dwell mostly in the daytime sky. But Martin Connors of Athabasca University in Canada and his colleagues used data from the Wide-field Infrared Survey Explorer (WISE), which launched in 2009 and has found more than 500 near-Earth objects. The researchers confirmed that the object, called 2010 TK7, was a Trojan through follow-up observations with telescopes in Hawaii.

The authors say the object’s behavior is fairly chaotic — it dances around the orbital plane with a tadpole-like motion. They say the asteroid might jump to other Lagrange points or orbital modes, and its stability can’t be guaranteed beyond about 7,000 years. The Earth better enjoy its pas de deux while it can.


  1. Report this comment

    Sage Carlson said:

    Is that a typo in the headline? For years now I’ve been hearing about this moon thing.

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    Patrick Smith said:

    I feel it is not a typo. The moon orbits around the Earth. From what I can tell from the article, this Trojan orbits around the sun in the same general orbit as the Earth, but in a rather odd pattern due to the effects of Earth’s gravitational pull on it. It is an orbital partner because it has the same orbit around the Sun as the Earth and maintains a fairly constant angle with Earth.

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    Antonio Carlos said:

    We haven’t few neighbors in this huge backyard!

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    diane fode said:

    that is a real non information !

    what about the trillions of

    atoms of Dust that turn around our Earth?

    What are their Lagrange Points ?

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    yeah said:

    they don’t count objects made of blue cheese

  6. Report this comment

    Zack Y said:

    Moon was invented by the government to beat the Russians in 1969, remember? No typo error.

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    manjeet chaturvedi said:

    Or is not the earth of 40,041 km circumference partner of 300 metre long rock? Could be other way round if a view of earth is taken from its so known Trojan!

  8. Report this comment

    ترانيم said:

    Moon was invented by the government to beat the Russians in 1969, remember? No typo error.

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