On April 20, 2007, the comet Encke had just dipped inside the orbit of Mercury, perilously close to the sun, when a solar eruption struck and literally tore the comet's tail off. This surely has happened to comets before, but for the first time in history a spacecraft was watching. NASA's STEREO-A probe recorded a fantastic movie of the collision.

The eruption that hit Encke was a CME or "coronal mass ejection." Sky watchers on Earth are familiar with CMEs because of the auroras they create when they occasionally hit our planet. CMEs are fast-moving and massive, packing billions of tons of solar gas and magnetism into billowing clouds traveling a million-plus miles per hour.

To read more, go to http://science.nasa.gov/headlines/y2007/01oct_encke.htm

Be sure to watch the movie of the comet's tail being blown away.

Neptune's Moon Triton Occults Star

The image above is Neptune (near center) with its moon, Triton, at the 4 o'clock position. Just beyond Triton, just a wee bit further to the right, is a star. I watched Neptune move slowly until Triton occulted the star on September 20th.

Go to http://www.myslooh.com/data/members/1627/1190342291.gif to see an animated GIF I made from combining several images of Neptune's moon, Triton, occulting a star.