Uranus is the seventh planet from the Sun in our solar system, a giant ball of gas and ice about four times wider than Earth. It's so far away that it takes sunlight nearly three hours to reach it (compared to just eight minutes to reach Earth).

What makes Uranus truly strange is that it's tipped on its side. While most planets spin upright like tops, Uranus rolls around the Sun like a barrel rolling down a hill. Scientists think a massive collision billions of years ago knocked it sideways. This odd tilt means that during Uranus's 84-year orbit, each pole faces the Sun for 42 years of continuous daylight, then 42 years of darkness.

Through a telescope, Uranus appears as a pale blue-green dot. That color comes from methane gas in its atmosphere, which absorbs red light and reflects blue and green. The planet has at least 27 known moons, many named after characters from Shakespeare's plays, and a set of thin, dark rings that circle it. Because of Uranus's unusual tilt, its rings and moons are tilted, too.

Uranus was the first planet discovered in modern times. Ancient astronomers knew about Mercury, Venus, Mars, Jupiter, and Saturn because they're visible to the naked eye, but Uranus was spotted through a telescope in 1781 by astronomer William Herschel. The planet was named after the ancient Greek god of the sky.