A comet-chasing spacecraft swinging by Earth this week has snapped magnificent new images of our home planet.
The new photos come from the European Space Agency's Rosetta spacecraft, which will make its closest approach by Earth Friday at 2:45 a.m. EST (0745 GMT), during its third and final flyby past the planet.
The Rosetta spacecraft's OSIRIS narrow-angle camera captured three images of Earth with an orange, green and blue filter, and from a distance of about 393,330 miles (633,000 km). The resulting illuminated crescent is a combination of the trio.
The combined image shows the Earth as blue sliver, with the South Pole roughly in the center. The outline of Antarctica is visible beneath the clouds that form the south-polar vortex, a natural continent-wide tornado of sorts. Pack ice in front of the coastline, due to its strong reflectivity, causes bright spots in the image.
Besides capturing stellar images, the flyby could help unravel a mystery that has stumped scientists for two decades. Space scientists have noticed craft vary the amount of orbital energy they exchange with Earth during planetary flybys. This variation shows up as a tiny difference in speed either gained or lost when compared with that predicted by fundamental physics and that actually measured after the event.
During tomorrow's flyby, scientists will track the craft's orbital energy, as they have no idea whether Rosetta will get a slight boost, brake, or experience no speed-change at all.
Rosetta was launched in 2004 with a 2014 goal of entering low orbit around the comet Churyumov-Gerasimenko, before selecting a landing spot so its small lander Philae can travel with the icy object as it moves toward the center of the solar system. Then, Rosetta should have a front row seat as the comet gets heated by the sun and sheds its outer layer, finally producing comets' claim to fame ? its tail.
- Video - Rosetta's Asteroid Rendezvous
- Top 10 Views of Earth from Space
- Images: Great Comets