The terminator, too 😎⁣ The terminator – the line between light and dark, or day and night – is what we’re looking at here in this image of Mercury. Days and nights are interesting on this little planet: sunrise and sunset don’t accompany each rotation like they do on most other planets. Instead, the morning Sun appears to rise briefly, set, and rise again from some parts of Mercury’s surface. The same thing happens in reverse at sunset for other parts of the surface.⁣ Mercury stands out in other ways as well. For instance, its egg-shaped orbit takes the planet as close as 29 million miles and as far as 43 million miles from the Sun. It’s also faster than any other planet – it speeds around the Sun every 88 days, traveling through space at nearly 29 miles per second.⁣ Image description: Mercury's surface looks a lot like that of Earth's Moon: It is scarred by many impact craters resulting from collisions with meteoroids and comets. Mercury’s surface is grayish brown, with some brigh...