In the 1950s Isaac Asimov wrote a series of science fiction novels set in various parts of the solar system with plots spun from the physical properties of each location. The one about Mercury was titled Lucky Starr and the Big Sun of Mercury. I'm feeling the urge for a meander through the solar system, so this will be the first stop, which you might want to call Plenty of Nothing and the Retrograde Sun of Mercury, because because of Mercury's somewhat elliptical orbit the sun can actually be seen to move backwards during the course of its day, which I declare is just too cool. Mercury is practically all metal core, to the extent that it's thought that early on in its history Mercury was brushed up against by another body, which caused the greater part of its rocky mantle to spin off into space. In fact all of the inner planets seem to have been involved in this kind of billiards in the first billion years of the solar system. A similar brush created the Moon. The Moon and Mercury look very much alike, but that's just coincidence. Or is it? [It is.] Douglas