Astronomy Picture of the Day Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. 2012 April 24



Rosetta Approaches Asteroid Lutetia

Images Credit: ESA / MPS / UPD / LAM / IAA / RSSD / INTA / UPM / DASP / IDA;

Video Compilation: Daniel Machacek / YouTube: planetaryprobes

Explanation: What would it look like to approach an asteroid in a spaceship? In 2010, ESA's robotic Rosetta spacecraft zipped past the asteroid 21 Lutetia taking data and snapping images in an effort to better determine the history of the asteroid and the origin of its unusual colors. Recently, many images from a camera always facing the asteroid were compiled into the above video. Although of unknown composition, Lutetia is not massive enough for gravity to pull it into a sphere. The 100-kilometer across Lutetian was at that time the largest asteroid or comet nucleus that had been visited by a human-launched spacecraft. Orbiting in the main asteroid belt, Lutetia shows itself to be a heavily cratered remnant of the early Solar System. Now well past Lutetia, the Rosetta spacecraft is continuing onto comet Churyumov-Gerasimenko where a landing is planned for 2014.