> Which planet has the most tilt out of all the planets, so much so that itessentially spins on its side?And the answer: Uranus.The seventh planet from the sun, Uranus has an axis of rotation that makes itappear to be tilted sideways, at nearly 90 degrees to its orbit. Each pole getsaround 21 Earth years of sunlight during its summer season, and 21 years ofdarkness in winter.Photo credit: (Pixabay Photo).For centuries, astronomers have been able to studyand document our neighboring planets. Mars, Venus, Jupiter, and even Saturn havebeen researched for centuries, dating back even before Galileo's advancements intelescopic science. However, another more elusive planet lay just out of sight:Uranus. This peculiar planet revolves around the sun some 20 astronomical unitsfrom Earth (i.e., 20 times the distance between Earth and the sun), making itnearly impossible to see with the naked eye. For this reason, astronomers longbelieved the ice giant to be a star. And why shouldn't they? Uranus' greatdistance from the sun (and massive size) leaves it with a very slow, nearlyimperceptible revolution around the sun: once every 84 Earth years. Also due to its distance from the sun, Uranus is one of the coldest planets inthe solar system. Its icy temperatures – sometimes dropping as low as -370degrees Fahrenheit – are largely due to the planet's composition. While its core(which on its own is roughly the size of Earth) is comprised of iron andmagnesium silicate, the remaining 80% of the planet is made up of water, ammoniaand methane. Beyond being responsible for its blue color, this ocean of ice andgas makes the planet incredibly cold.Meanwhile, Uranus' peculiar tilt is thought to be the result of a collision withanother celestial body millions of years ago. As a result, Uranus' rings andmoons orbit the planet vertically. It is the only planet in our solar system todo so. Learn more about the gaseous, distant giant below.