NASA’s Dawn spacecraft entered orbit around Ceres at approximately 7:40 ET on the morning on March 6, the first time a spacecraft has orbited a dwarf planet. Ceres is the largest asteroid and the first discovered, on January 1, 1801. Originally classified as a planet, it was re-classified as an asteroid when it was clear that it was only one of many objects between Mars and Jupiter. Dawn previously orbited Vesta, the second largest asteroid and the fourth discovered, from 2011-2012. This is the first time a spacecraft went into orbit around two objects outside the Earth-Moon system. Dawn will begin its study of Ceres next month and will remain in orbit until 2016.
Astronomers have discovered the first known asteroid with a ring. Asteroid 10199 Chariklo, an asteroid orbiting between Saturn and Uranus, is the first object known to have a ring that isn’t a gas giant. The two concentric rings are dense, thin, and bright according to astronomers. The outer ring is 3 km wide and the inner ring is 6.5 km wide with a gap of 9 km between the rings. Chariklo is 250 km wide.
The Chelyabinsk region of Russia was struck by a ten ton meteorite on the morning of February 15, just hours before a 150 foot asteroid is scheduled to pass between Earth and communications satellites. The shock waves from the meteor passing through the atmosphere blew out glass in six cities and four towns, damaged more than 100,000 square meters of glass, and caused nearly 1,000 injuries, most of them related to flying glass.
Astronomers have discovered the first asteroid to orbit in the leading Lagrange point of the Earth. 2010 TK7 is nearly 300m across and has an irregular orbit which can bring it within 20 million kilometers of the Earth. The asteroid was discovered by the Near Earth Orbit project using the WISE satellite, launched in 2009.
The Stardust probe, which was launched in 1999 to study the asteroid 5535 Annefrank and Comet Wild 2, was shut down by NASA on March 24. In addition to its primary mission, which ended when a capsule of dust from Comet Wild were returned to Earth, Stardust had a flyby of Comet Tempel 1 earlier this year to follow-up on the mission of the 2005 Deep Impact probe. Before shutting down, Stardust notified NASA of its remaining fuel to help gauge consumption of future missions and then burned off 146 seconds worth of fuel.
Although astronomers created a definition for a Dwarf Planet in 2006, the definition only dealt with the upper size limit. Now, astronomers Charles Lineweaver and Marc Norman at the Australian National University in Canberra, have offered a definition for the lower end of dwarf planets, stating that a dwarf planet must have a circumference of at least 200 miles. Lineweaver and Norman selected that figure because anything larger will naturally form into a sphere, while anything small will retain a lumpier shape. The IAU has yet to debate and vote on the issue.
For the first time, meteorites from an asteroid which had been tracked in space have been recovered. Researchers at the Catalina Sky Survey in Arizona spotted an asteroid on a course for Earth. JPL confirmed it would intersect with the planet and the asteroid was tracked until it exploded at an altitude of 37 miles. Following its disintegration, meteorites were found by students in the Sudan desert. The meteorite’s composition matches spectroanalysis performed on the asteroid by La Palma in the Canary Islands.