Mercury is a small, rocky planet that’s the closest planet to the Sun. Due to its close proximity its years are relatively short, taking just 88 Earth days to complete an orbit. But its days are long, taking over 116 Earth days for the planet to rotate.
Its surface is thoroughly baked during the day, reaching 427 °C (800 °F) and as it has no atmosphere to retain this heat, nighttime temperatures fall to −173 °C (−280 °F). There may be a thin, constantly shifting zone on the planet’s surface (after sunset and before sunrise) where temperatures may be briefly within survivable limits.
Mercury’s orbit is elliptical, which means its body is slightly warped when it reaches its closest point to the Sun. This creates internal friction, creating heat, which keeps Mercury’s core in a liquid state.
This liquid core means that heat can move liquid iron around, creating a strong magnetosphere for the planet. It both deflects and absorbs solar wind. The magnetosphere is ‘leaky’, containing magnetic ‘tornadoes’:
Twisted bundles of magnetic fields [connect] the planetary magnetic field to interplanetary space – that [are] up to 800 km wide or a third of the radius of the planet. - Wikipedia, Mercury (planet)
The surface of the planet is etched and scatted, reflecting these extreme conditions.
However there are huge volumes of ice at its poles inside of deep craters which are never exposed to direct sunlight. Primitive microorganisms may have once existed on the planet in habitable subsurface zones.
