FARSIDE PLANETARY CONJUNCTION: Mercury and Saturn are converging for a tight conjunction in the night sky. Just one problem: You have to be on the far side of the sun to see it. NASA's STEREO-B probe is perfectly positioned to observe the convergence:
Late in the day on Saturday, May 17th, the distance between the two planets will narrow until they become nearly indistinguishable. If this event were visible from our side of the sun, it would surely be headline news.
NASA's STEREO probes see many things that we cannot. From their orbits high above the farside of the sun, they track hidden sunspots, anti-Earth-directed solar flares, and intterplanetary CMEs. STEREO's wide-field Heliospheric Imagers also have a unique view of the planets. See above. This weekend's conjunction of Mercury and Saturn is bracketed by Mars and Earth itself, an arrangement impossible to observe from terra firma. http://www.spaceweather.com
