NASA Sees the Dark Side of the Sun

NASA Sees the Dark Side of the Sun. Yes that's kind of a joke, but the STEREO spacecraft are two solar observatories that are in earth's solar orbit, ahead of and behind the earth, and that are schedule to be on opposite sides of the sun.

"STEREO's deployment on opposite sides of the Sun solves a problem that has vexed astronomers for centuries: At any given moment they can see only half of the stellar surface. The Sun spins on its axis once every 25 days, so over the course of a month the whole Sun does turn to face Earth, but a month is not nearly fast enough to keep track of events. Sunspots can materialize, explode, and regroup in a matter of days; coronal holes open and close; magnetic filaments stretch tight and—snap!—they explode, hurling clouds of hot gas into the solar system. Fully half of this action is hidden from view, a fact which places space weather forecasters in an awkward position. How can you anticipate storms when you can't see them coming? Likewise researchers cannot track the long-term evolution of sunspots or the dynamics of magnetic filaments because they keep ducking over the horizon at inconvenient times. STEREO's global view will put an end to these difficulties. The global view is still two years away. Already, however, the two spacecraft are beaming back over-the-horizon images that have researchers and forecasters glued to their monitors."