Uranus: Discovery, Atmosphere, Interior, Rings, and Moons

Uranus

Seventh planet from the Sun, discovered in 1781.

William Herschel

Astronomer who discovered Uranus in 1781.

Georgium Sidus

Original name given to Uranus by William Herschel.

Voyager 2

NASA spacecraft that visited Uranus in 1986.

Uranus’s Distance from the Sun

Approximately 1,780,000,000 miles.

Uranus’s Size

31,693 miles in diameter.

Uranus’s Orbital Period

84.01 years.

Uranus’s Rotational Period

17.24 hours (retrograde).

Uranus’s Inclination of rotation axis

97.86º, causing extreme seasonal variations.

Impact Theory of Uranus

Hypothesis that an Earth-sized protoplanet caused Uranus' high inclination of rotation axis.

Uranus’s Number of Satellites

27 known moons.

Uranus’s Atmosphere Composition

Hydrogen (83%), helium (15%), and methane (2%).

Ammonia

Not observed in Uranus' upper atmosphere due to low temperature.

Uranus Atmospheric Structure

Blue-green color, few discernible features, seasonal weather effects.

Clouds in Uranus atmosphere

Composed of condensed methane, exhibit banded pattern parallel to latitude lines.

Haze

Tenuous haze in Uranus' upper atmosphere, giving the planet its blue-green hue.

Uranus’s Interior Composition

Core of silicate rock, icy mantle, and gaseous hydrogen/helium envelope.

Diamonds

Extreme pressure and temperature may cause methane molecules to break up into _____ crystals.

Magnetic Field

Generated by ionized water and ammonia within the mantle.

Offset and Tilted Magnetic Field

Uranus' magnetic field is not centered and tilted almost 60º with respect to the axis of rotation.

Internal Heat

Uranus radiates less heat than it receives from the Sun, reasons still under debate.

Discovery of Uranus Rings

Discovered unexpectedly in 1977 during a stellar occultation experiment.

Ring Structure and Composition

Eleven narrow rings composed of dark particles, possibly carbonaceous material.

Outer Ring System of Uranus

Two additional rings discovered in 2005, possibly composed of water-ice particles originating from small impacts of a minor moon

Uranus’s Ring Origin

Thought to be the result of collisional fragmentation of moons that once existed around Uranus.

Major Moons

Miranda, Ariel, Umbriel, Titania, and Oberon.

Miranda

Moon with extreme and varied topography, including the tallest known cliff in the solar system.

Ariel

Moon with bright and young surface, extensive system of fractures and faults.

Umbriel

Moon with dark surface, heavily impacted, presence of canyons that suggests early tectonic process

Titania

Moon with similar surface to Ariel, intersected by scarps and canyons and underwent an active phase in which cyrovolcanism erased the early craters

Oberon

the oldest of Uranus’ moons. with heavily cratered surface, intersected by canyons, and a multi-ringed

Uranus’s Minor Moons

22 irregularly shaped and dark moons, possibly captured asteroids or fragments from collisions.

Coronae

Miranda’s broken terrain consists of three large grooved
structures referred to as coronae, which may be the result of “warm” ice upwelling from the moon’s interior.