The planet Mercury. This mosaic shows the planet Mercury as seen by Mariner 10 as it sped away from the planet on March 29, 1974. The mosaic was made from over 140 individual TV frames taken about two hours after encounter, at a range of 37,300 miles. North is at top. The limb is at right, as is the illuminating sunlight. The equator crosses the planet about two-thirds of the way from the top of the disc. The terminator, line-separating day from night, is about 190 degrees west longitude (NASA Media Archives). Buy this as a superb wall poster, a canvas print or a framed print.