Western astronomer shares discovery of first Trojan asteroid found in Earth’s orbit

Studying images compiled by NASA, an astronomer from The University of Western Ontario has proved the existence of the first Trojan asteroid found to share Earth’s orbit. The findings of Paul Wiegert and his colleagues at Athabasca University and the Canada-France-Hawaii Telescope were published today as the cover story for the July 28 issue of distinguished journal, Nature.  

A Trojan asteroid shares an orbit with a larger planet or moon, in this case Earth, but does not collide with it because it follows the same orbital path. Before this discovery, only the planets Jupiter, Neptune and Mars were known to harbour these asteroids named for the soldiers of the ancient war immortalized by Homer in The Iliad and The Odyssey.

“Like a pair of dancers performing a complicated tango, the asteroid moves in an elaborate path that brings it sometimes closer and sometimes farther from us,” says Wiegert, a professor in Western’s Department of Physics and Astronomy. “The Earth and the asteroid remain in sync however, with the asteroid always preceding the Earth as they both move around the Sun.”

Currently known as Asteroid 2010 TK7, the as-yet-unnamed near-Earth asteroid (NEA) was discovered by the Wide-field Infrared Survey Explorer satellite in October 2010. Following the discovery, the possible co-orbital nature of the asteroid was first deemed a possibility by Martin Connors from Athabasca.

Images of the asteroid were then taken by Christian Veillet, Executive Director of the Canada-France-Hawaii Telescope in Hawaii, to refine the asteroid’s orbit once it was favourably placed in the night sky. Based on these new images, Wiegert was able to create computer simulations of Asteroid 2010 TK7, which confirmed the Trojan character of its motion.

“These asteroids are very interesting as individual members of the near-Earth asteroid population but they also tell us a lot about how the Earth and asteroids interact gravitationally at a distance,” says Wiegert. “Because this asteroid is a Trojan asteroid, it interacts with the Earth in a very special way allowing us a unique opportunity to study near-Earth asteroids.”

Trojan Asteroid simulation videos

The camera moves to give a clearer view of the 3D shape of the orbit of 2010 TK7. Note: This clip is only illustrative of the orbits involved. In particular, the number of loops has been reduced for easier visibility, and the sizes of the Sun, Earth and the asteroid have been exaggerated for the same reason. As a result, the asteroid appears to pass much closer to the Earth than it does in reality.

The Sun is at the centre of the image, the Earth at the bottom. The path of the asteroid is shown in green: the spaces between loops have been expanded for clarity. Note: This clip is only illustrative of the orbits involved. In particular, the number of loops has been reduced for easier visibility, and the sizes of the Sun, Earth and the asteroid have been exaggerated for the same reason. As a result, the asteroid appears to pass much closer to the Earth than it does in reality.

Renderings of the Trojan Asteroid

Computer Illustrated Image 1

Computer Illustrated Image 2

• What is a Trojan asteroid?
• What makes it unique?
• How does a Trojan asteroid share Earth's orbit?
• How was Earth's first Trojan asteroid discovered?
• Is Earth the only planet with a Trojan asteroid?
• What can we learn?
• Will this Trojan asteroid affect the Earth's climate?
• Are Trojan asteroids safe?
• Could Earth collide with this Trojan asteroid?