Closest to the sun
The planet closest to the sun is Mercury. It is one of the smallest of
the nine planets—only a little more than one-third the size of the
earth. Seen from the earth, Mercury appears, disappears, and appears
again. This is why it was named after the Roman god Mercury. As the
messenger of the gods, Mercury was thought to move swiftly back and
forth between heaven and earth.
Mercury, much like our moon, is a bare, rocky ball covered with billions
of craters. In Mercury’s sky, the sun appears many times bigger and
brighter than it looks from earth. This is because Mercury is only about
36 million miles (57.9 million kilometers) away from the sun. The side
of Mercury facing the sun is tremendously hot. The other side is
fiercely cold.
A year on Mercury is only as long as 88 of our days. That’s how long it
takes Mercury to move all the way around the sun. But a day on Mercury
is equal to 59 of our days! Mercury spins around so slowly that its day
is nearly as long as its year.
the surface of Mercury
Mercury is very much like our moon. It is a bare ball of rock, covered
with craters.
