Looking all the world like sperm cells whipping their tails to propel themselves toward an egg, comets Encke and Ison are seen in this animation of spacecraft images swimming through the solar wind toward the sun.
This is actually the first view of Comet Ison from one of NASA’s two STEREO spacecraft. The dark, cloud-like features coming in from the right are actually denser concentrations of the particles streaming outward from the sun that comprise the solar wind. This is what’s causing Encke’s tail to ripple and whip back and forth.
As you’ve probably heard, Ison will be rounding the sun on Nov. 28, 2013, passing within a mere 700,000 miles of it. Considering that the sun is about 870,000 miles across, this will be a very close encounter — and Ison may not survive it intact.
Encke orbits the sun every 3.3 years. But for Comet Ison, this is its first trip around the sun. And that’s really significant, according to NASA, because it means that: