All About the Sky

Atmospheric rivers are huge streams of water vapor in the air. An atmospheric river forms when warm water vapor from the ocean flows toward cooler land masses. Discover more in Water Vapor, a title in the All about the Sky series.

It takes the Moon slightly less than a month to rotate on its axis. This is one day on the Moon. Discover more in Moon Phases, a title in the All about the Sky series

Earth's North and South Poles point toward the Sun at different times of the year. Seasons depend on which pole is pointing toward the Sun. Discover more in Seasons, a title in the All about the Sky series.

The four biggest planets in the Solar System are Jupiter, Saturn, Uranus, and Neptune. Jupiter is the largest of these, with a diameter of 88,846 miles (142,984 km). Discover more in Planets, a title in the All about the Sky series.