Which planet has the most tilt out of all the planets, so much so that it essentially spins on its side?
And the answer: Uranus.
The seventh planet from the sun, Uranus has an axis of rotation that makes it appear to be tilted sideways, at nearly 90 degrees to its orbit. Each pole gets around 21 Earth years of sunlight during its summer season, and 21 years of darkness in winter.
For centuries, astronomers have been able to study and document our neighboring planets. Mars, Venus, Jupiter, and even Saturn have been researched for centuries, dating back even before Galileo's advancements in telescopic science. However, another more elusive planet lay just out of sight: Uranus. This peculiar planet revolves around the sun some 20 astronomical units from Earth (i.e., 20 times the distance between Earth and the sun), making it nearly impossible to see with the naked eye. For this reason, astronomers long believed the ice giant to be a star. And why shouldn't they? Uranus' great distance from the sun (and massive size) leaves it with a very slow, nearly imperceptible revolution around the sun: once every 84 Earth years.
Also due to its distance from the sun, Uranus is one of the coldest planets in the solar system. Its icy temperatures – sometimes dropping as low as -370 degrees 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 and magnesium silicate, the remaining 80% of the planet is made up of water, ammonia and methane. Beyond being responsible for its blue color, this ocean of ice and gas makes the planet incredibly cold.
Meanwhile, Uranus' peculiar tilt is thought to be the result of a collision with another celestial body millions of years ago. As a result, Uranus' rings and moons orbit the planet vertically. It is the only planet in our solar system to do so.
Learn more about the gaseous, distant giant below.