Uranus

Uranus’s axial tilt, magnetic anomalies, and icy composition make it a puzzle for planetary scientists.

Telescopic picture of planet Uranus

Introduction

Uranus is an ice giant famed for its unprecedented axial tilt – it rotates on its side at 97.77°, so it looks like it's rolling around the Sun. It has 13 thin rings, 28 moons, and ferocious winds. Uranus was the first planet to be found telescopically, by William Herschel in 1781.

Potential for Life

Although Herschel intended to name it after King George III, astronomers settled on Uranus, after the Greek god of the sky. Uranus is too cold, windy, and high-pressure to support life as we know it. Some moons might have oceans beneath their surfaces, but conditions are still harsh.

Properties

Property	Value
Size and distance	Diameter: 51,118 km (4 times wider than Earth) Distance from the Sun: 2.9 billion km (19 AU) Sunlight travel time: 2 hours 40 minutes
Orbit and Rotation	One day: 17 hours One year: 84 Earth years Severe seasons due to sideways tilt: each pole is facing the Sun for ~21 years Uranus also rotates retrograde, like Venus, in an opposite direction to most planets.
Moons	Uranus has 28 known moons, named mostly after Shakespearean and Alexander Pope characters (e.g., Titania, Oberon, Ariel, Miranda). Inner moons: icy + rocky makeup Outer moons: probably captured asteroids
Rings	Uranus has 13 known rings, in two sets: Inner rings: dark and narrow Outer rings: include a red ring and a blue ring, like Saturn's Rings are: Zeta, 6, 5, 4, Alpha, Beta, Eta, Gamma, Delta, Lambda, Epsilon, Nu, Mu.  Structure and Formation Formed ~4.5 billion years ago Likely formed closer to the Sun, then drifted outward. Made up of: hot fluid ices (water, ammonia, methane) + a small rocky core Temperature near core internally: 9,000°F (~4,982°C)

Surface and Atmosphere

• No solid surface

• Atmosphere: mostly hydrogen, helium, methane

• Red light is absorbed by methane, so Uranus looks blue-green.

• Winds: 900 km/h

• Coldest planet in some spots: -224.2°C

Magnetosphere

• The magnetic field is 60° tilted and off-center.

• Creates a twisted, corkscrew-shaped tail

• Auroras are irregular and non-pole-oriented

  
  

Scientific diagram of Uranus

Summary

Uranus is a cold, blue-green ice giant that rotates on its side with a 98° tilt, causing extreme seasons that last over 20 years. It was discovered in 1781 and is made of icy fluids, hydrogen, helium, and methane, giving it its unique color. Uranus has 13 rings, 28 moons (named after literary characters), and fierce winds up to 900 km/h. It has no solid surface and is one of the coldest planets, reaching –224°C. Its magnetic field is tilted and off-center, creating unusual, off-pole auroras and a twisted magnetic tail. While Uranus is uninhabitable, some of its moons may hide subsurface oceans.

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