Uranus

The sideways world

Vital statistics

• Mean radius: 25,362 kilometres
• Mass: 8.68 × 10²⁵ kilograms
• Surface gravity: 8.87 metres per second squared
• Sidereal rotation: 17.2 hrs (retrograde)
• Orbital period: 84 yrs
• Mean temperature: -195 °C
• Known moons: 28
• Axial tilt: 97.77 degrees

Field notes

• Uranus rolls around the Sun on its side. Its poles take turns facing the Sun, so each gets 42 years of daylight followed by 42 years of night.
• It is the coldest planet — down to −224 °C — even though Neptune is 50% farther from the Sun. Uranus mysteriously leaks almost no internal heat.
• It was the first planet ever discovered with a telescope, in 1781 — and was nearly named 'George' after King George III.
• Its clouds contain hydrogen sulfide. Uranus, in all likelihood, smells of rotten eggs.

Data: NASA Planetary Fact Sheets. Explore the full interactive 3D map at the home page — every orbit is computed from real Keplerian elements.