ScienceCasts: Two Comets to Fly By Mercury on Nov 18 & 19 - HD
2013-11-16 22 Dailymotion
Consider it a cosmic coincidence: On Nov. 18-19, two comets (ISON and Encke) are going to fly by the planet Mercury in quick succession. NASA's MESSENGER spacecraft will have a front-row seat for the rare double flyby.
