Return to Mercury

After posting about pictures back from Jupiter and Saturn, and looking out to the anarchic and ambiguous outer fringe of the solar system, I find news drawing me in, much closer to the Sun. Today is the day that MESSENGER (the name is a complicated acronym) passes by Mercury for the first time; the last time a space probe did that was before I was born. Mariner 10 managed to bank down into the light-drenched environs of the innermost solar system and make three passes by Mercury taking pictures, but the same part of the planet was in sunlight every time; the hoary science fictional impression that half of Mercury never saw the Sun at all might as well have been true up to now. Of course, I'm not really expecting that the unseen half of Mercury will be surprising in the way the "other side of the Moon" managed to be forty-nine years ago, but it'll be interesting for me for uncertainty to be converted into knowledge of whatever sort.