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The Mysterious World of Uranus, the Ice Giant

Take a celestial journey into the mysteries of the ice giant, Uranus. Explore its exotic atmosphere and icy landscapes.

By Matt Hrodey
May 15, 2023 2:00 PMMay 17, 2023 2:29 PM
Uranus, where a cool exterior hides harsh conditions within. (Credit: 24K-Production)


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As the third furthest planet from the sun (assuming you count the dwarf planet Pluto), Uranus is a ball of contradictions, hot and yet cold, placid-looking and yet churning beneath.

Scientists are still sorting out basic questions about this ice giant, including whether it has a large mantle made of “hot ice.”

Here are some facts about the pale blue planet, the first discovered in modern times.

When Was Uranus Discovered?

William Herschel looks through the eyepiece as his sister, Caroline Herschel, takes notes on the night they discovered Uranus in 1781. (Paul Fouché/Wikimedia Commons)

In 1781, pioneering astronomer William Herschel first spotted Uranus using one of his self-built telescopes, but he initially mistook it for a comet or star.

He changed his mind, however, after calculating the object’s orbit, which turned out to be remarkably circular, not elliptical like a comet.

Read More: How the James Webb Space Telescope Takes Such Stunning Pictures

How Did Uranus Get Its Name?

This is an updated montage of planetary images taken by spacecraft managed by NASA’s Jet Propulsion Laboratory in Pasadena, CA. Included are from top to bottom images of Mercury, Venus, Earth and Moon, Mars, Jupiter, Saturn, Uranus and Neptune. (Credit: NASA/JPL)

Herschel initially put forth the name of Georgium Sidus, after King George III, but the scientific community later accepted another suggestion, Uranus, proposed by astronomer Johann Elert Bode.

Uranus was the first planet discovered in 2,000 years, according to the Science History Institute, since humans had previously spotted Venus, Mercury, Mars, Jupiter and Saturn with the naked eye. While all these names came from Roman gods, Uranus invokes the Greek god of the sky.

What Is Uranus Made of?

An infrared composite image of the two hemispheres of Uranus obtained with Keck Telescope adaptive optics. (Credit: NASA/Lawrence Sromovsky, University of Wisconsin-Madison/W.W. Keck Observatory)

At the atmospheric level, Uranus is a mixture of hydrogen and helium and methane, the last of which serves as a bluish shroud, hiding storms in the cloud decks below.

Uranus’ great mantle is made of a black, slow-moving substance called “superionic ice,” scientists have hypothesized. Formed by intense pressures, this hot ice breaks apart water molecules, setting the hydrogen loose and locking the oxygen in a cube structure.

Read More: Earth Isn't the Only Ocean World in the Solar System

What Is the Temperature of Uranus?

NASA Hubble Space Telescope peered deep into Uranus atmosphere to see clear and hazy layers created by a mixture of gases. Using infrared filters, Hubble captured detailed features of three layers of Uranus atmosphere. (Credit: NASA/JPL/STScI)

Winds on deceptively placid Uranus can surpass 500 miles per hour, and temperatures can drop as low as 430 degrees below zero, lower than on any other planet in the solar system.

The fourth smallest gas giant planet is still large enough (14.5 times the mass of Earth) to create massive pressure and high temperatures within its mantle and core, which can reach 9,000 degrees.

Read More: Winter May Seem Cold, But It's Nothing Compared To Outer Space

How Many Moons Does Uranus Have?

This Voyager 2 picture of Oberon is the best the spacecraft acquired of Uranus' second-largest moon. (Credit: NASA/JPL)

The planet has 27, all of which were named after characters from the works of Shakespeare (Juliet, Caliban, Oberon, Titania) or Alexander Pope. Some may have originated in a distant collision, back when the solar system was a younger and more crowded place.

According to one theory, a Mars-sized moon fell into a deteriorating orbit and smashed into the planet, leaving behind debris that slowly formed into moons. This pummeling may also be responsible for the planet’s unique tilt, although another theory contends that an ancient satellite could have tilted the planet by mere gravitational influence.

A similar theory proposes that the Earth and moon formed from the dramatic collision of a Mars-sized object, dubbed Theia, and an early, proto-Earth. When the dust settled some 4.5 billion years ago, our Earth and moon were left standing.

Read More: A Telescope on the Moon Could Illuminate the Dark Ages of the Universe

Can Humans Go to Uranus?

These three NASA Hubble Space Telescope images of the planet Uranus reveal the motion of a pair of bright clouds in the planet southern hemisphere, and a high altitude haze that forms a cap above the planet south pole. (Credit: NASA/JPL/STScI)

Don’t plan on booking a SpaceX trip to Uranus anytime soon, according to people at NASA.

“While a spacecraft would have nowhere to land on Uranus, it wouldn’t be able to fly through its atmosphere unscathed either,” the space agency advises. “The extreme pressures and temperatures would destroy a metal spacecraft.”

Uranus has a short day in the technical sense, meaning it rotates on its axis once every 17 hours. But that doesn’t mean you can “stand” on the planet and watch a sunset every 17 hours.

For reasons not fully understood, Uranus’ axis is tilted about 90 degrees to the side, meaning the planet’s rotation doesn’t cause sunsets – its revolution around the sun does. As such, you’d have to wait potentially decades (up to 84 years) to watch the sun go down, depending on your position on the planet.

Read More: How Old Is the Sun?

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