The nighttime sky is a vast expanse that becomes visible after sunset. It is filled with stars, planets, and sometimes the moon, which reflects sunlight. The stars are distant suns, and their light takes years to reach Earth. The sky can also display various celestial events, such as meteor showers and the appearance of comets. In addition to stars, the nighttime sky often features constellations, which are patterns formed by groups of stars. Astronomers study these patterns to understand the universe better. The sky can also show the Milky Way, a band of light created by countless stars, and satellites that orbit Earth.