Playing tag with a "trojan," 08.05.11

Astronomers have recently discovered that Earth is not alone. It seems our planet is being followed, or our Earth is following something else, depending on how you look at it. Earth’s orbit is being shared by an object that astronomers refer to as a “trojan” asteroid.

Thanks to data gathered from the NEOWISE project, astronomers have discovered that there is an asteroid roughly 1,000 feet in diameter that shares almost the exact same orbit as Earth as it travels around the sun. While the asteroid, dubbed 2010 TK7, does at times travel above, below, or slightly to the side of Earth’s orbit, for the most part it seems as if Earth and the asteroid are following in each other’s tracks. 2010 TK7 does travel a little farther away from the sun than Earth does at times, as well.

So, why have astronomers not noticed it until now? It seems that 2010 TK7 is usually difficult to spot because from our vantage point on Earth, it would always appear to be close to the sun. For obvious reasons, this makes it very difficult to observe. The NEOWISE project changed the game though. NEOWISE is an aspect of the WISE (Wide-field Infrared Survey Explorer) mission, a telescope in space far removed from Earth’s atmosphere and the glare of our daylight. The “NEO” part of the name is a side-mission of the probe that searches for Near Earth Objects, bodies that pass within 28 million miles of the sun. By observing 2010 TK7 from outside of our atmosphere, astronomers were able to get a pin point on it and then track it down much easier using other observatories here on Earth, namely the Canada-France-Hawaii telescope on mount Mauna Kea in Hawaii.

Is Earth in danger from its stony stalker? No. According to NASA, trojans are fairly common in our solar system. Neptune, Mars, Jupiter, and even two of Saturn’s moons all have trojans. 2010 TK7 also seems to have a stable orbit, as well, so it is not likely to interfere with Earth.

“It’s as though Earth is playing follow the leader,” said Amy Mainzer, the principal NEOWISE investigator.

Let us hope there are no sore losers in space.

Credit: NASA.