Earth’s Trojan Asteroid

We are not alone

Artist's concept provided by NASA illustrates the first known Earth Trojan asteroidArtist’s impression of the obit of the Trojan asteroid

Astronomers using Nasa’s Wide-field Infrared Survey Explorer (Wise) have spotted Earth’s first “Trojan” asteroid.

Trojans are asteroids that share the same orbital path as a planet (see the Nasa animation), but because the constantly lead or follow on behind, they’re incredibly difficult to spot from the ground.

The side-on view we have of the rest of the solar system means that trojans orbiting other planets are much easier to spot. Neptune, Mars and Jupiter all have them, and scientists have speculated that the earth too might have its own shadowy doppelganger.

Using the perspective offered by the Earth-orbiting Wise telescope, the team – lead by Martin Connors at the Athabasca University in Canada – set out to confirm that theory by scanning the entire sky in infrared light. They spotted two candidate asteroids, one of which has now been confirmed as Earth’s first true trojan.

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