20150311 - ceres

NASA’s Dawn Probe Has Arrived at Dwarf Planet Ceres

By Sarah Scoles | March 6, 2015 10:27 am

Today, dwarf planet Ceres became the first such planet to have company over. The visitor is NASA’s Dawn spacecraft, which reached its final destination — an orbit around this 590-mile-wide ball of ice and rock — after more than seven years in space.
And now that Dawn is finally all up on this space rock, astronomers can take sharp snapshots of its surface and learn about what makes Ceres Ceres, which they’ll do for the next 16 months. In the process, they will investigate why some planet-like objects didn’t quite grow into planets (sorry, Pluto — we’re looking at you), what the solar system was like billions of years ago, and what that tells us about Earth today.

A New Day for Dawn

NASA launched Dawn in 2007, way back when Steve Jobs first announced this crazy thing called an iPhone. It traveled for four years to arrive at Vesta, a giant asteroid, where it spun around the surface for 14 months. Then, in 2012, Dawn’s ion drive (for real) propelled it out of orbit and back on its journey.
It began its approach to Ceres in December, beaming back HD images of the dwarf planet starting in late January.
Today, it becomes not just the first spacecraft to visit a dwarf planet but also the first spacecraft to orbit two different non-earthly objects. Guinness Book: Are you listening?

Origin Story

Sicilian astronomer Giuseppe Piazzi first saw Ceres in 1801. He called it a planet. But soon, other observers began to see more stuff like Ceres in the same region of space. That area became known as the asteroid belt, and Ceres became an asteroid. But Ceres is huge. If you spread its surface over the United States, it would cover more than one-third of the continental land.
So in 2006, at the same time that Pluto got demoted, Ceres received a promotion: both “bodies” (as astronomers call them) are now officially dwarf planets. They have enough gravity to pull themselves into spheres, but they haven’t swept up or kicked out all the debris in their orbits.


 http://blogs.discovermagazine.com/d-brief/2015/03/06/nasa-dawn-ceres/#.VQBDq45AvEQ