The European Space Agency wowed the world on Wednesday, landing a probe on a moving comet after orbiting around it. The probe, Philae, and its mother-ship, Rosetta, will hopefully retrieve samples that could help scientists understand more about the formation of the earth and solar system.
Let’s talk about that 4.6 billion-year-old comet.
On Thursday, according to the ESA, the comet -- named Churyumov–Gerasimenko, or more simply 67P -- is traveling at 11.4 miles per second. Every 6.45 years, it completes its orbit around the sun. Right now, it's roughly 310 miles away from Earth (if you're thinking about your childhood solar system diorama, place it between Mars and Jupiter). Comets are constantly spinning (this one completely rotates every 12.4 hours, just over half the time earth's rotation takes), are covered in ice and rock, and have an extremely uneven surface, one of the many things that made this mission particularly difficult.
Comets date back to the formation of the solar system and scientists believe they may be able to tell us how our universe was created. To reach the comet, it took Rosetta ten years, $1.8 billion dollars, and 4 billion miles of traveled space (thanks to the loop-the-loop path you can see on this ESA website by selecting "show full path"). The comet is so far away that it takes 28 minutes for data to be transmitted between mission control and Rosetta. In Earth terms, this comet is pretty big – the size of lower Manhattan—but in the scheme of the universe? Well, it’s a needle in a very, very big haystack.
Rosetta’s journey to the comet was not without hiccups: In 2011, it flew so far from the sun (half a billion miles away) it had to take a three-year nap because its solar panels couldn’t gather enough energy to operate. In January, however, Rosetta woke up and hurried on to the comet. The landing was a particularly difficult chapter of Rosetta and Philae's journey: It's still not clear whether the probe has secured itself to the surface of the comet so it can begin gathering samples and it actually took three tries to land on the comet. Still, some incredible photos have emerged.
"How audacious, how exciting, how unbelievable to be able to dare to land on a comet," NASA's director of Planetary Science, Jim Green, said after the touchdown.