A Mercury rover could explore the planet by sticking to the Terminator

The closest planet to our sun, Mercury, experiences extreme temperature variations. Since the planet has no atmosphere to speak of, it is in a constant cycle where one side is extremely hot and the other extremely cold. On the sun-facing side, temperatures reach a scorching 427°C (800°F), enough to melt tin and lead, and the surface is exposed to extremely lethal levels of radiation. On the night side, temperatures plunge to a chilling −173°C (-279.4°F), cold enough to freeze most liquids, including those used in battery manufacturing.