Image: Scott Sheppard.

Scott Sheppard and Gemini Observatory colleague Chad Trujillo have discovered the first Trojan asteroid, 2008 LC18, in a difficult-to-detect stability region at Neptune, known as Lagrangian L5 point. Their research is published in this week’s Science Express. Most Trojan asteroids have been found at others stable Lagrangian points near Jupiter and Neptune. Sheppard and Trujillo used this discovery to estimate the asteroid population at Neptune's L5 point and found that it is similar to that at the planet's L4 point.

Sheppard commented, “The L4 and L5 Neptune Trojan stability regions lie about 60 degrees ahead of and behind the planet, respectively. Unlike the other three Lagrangian points, these two areas are particularly stable, so dust and other objects tend to collect there. We found three of the six known Neptune Trojans in the L4 region in the last several years, but L5 is very difficult to observe because the line-of-sight to the region is near the bright center of our galaxy.”

For more, see the Science Express article or the CIW press release.