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When Was Uranus Discovered? History of Uranus

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Planet Uranus in the Starry Sky

Uranus was accidentally discovered on March 13, 1781¹, by astronomer William Herschel. The musician with a penchant for astronomy used a telescope he built himself, and although Uranus had been observed several times through a telescope over the previous century, it had always been dismissed as another star. The event marked the first-ever planet to be discovered with a telescope. 

The object that William Herschel first thought was a comet, turned out to be a wonderful planet, full of surprises. If you’d like to learn more about this planet, including fascinating facts, like why scientists believe it rains diamonds on Uranus, keep reading!

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A Brief Overview of Uranus

Uranus is the 7th planet in our solar system. It is classified as an ice giant, and like the gas giants in our solar system, it lacks a solid surface. Instead, Uranus is composed of hydrogen, helium, and lots of water, ammonia, and methane.

The planet is made of layered clouds. It’s believed that Uranus’s innermost clouds are composed of water, while the outermost layers of clouds are methane.

With its vibrant cyan color and unique name, Uranus has inspired¹ military operations, poetry, music, and comedy, making it one of the most interesting planets in our solar system.

planet uranus in the galaxy
Image Credit: NASA images, Shutterstock

History of Uranus

Like most astronomical discoveries, not everything about Uranus was revealed simultaneously. As knowledge and technology have advanced, so has our knowledge of Uranus. Below, we’ve written a timeline that spans all the Uranus-related discoveries since Herschel first spotted a glinting object in his homemade telescope.

The 1700s – The Discovery of Uranus, Titiana, and Oberon

When William Herschel first spotted a glinting object in his telescope in March 1781, he initially mistook it for a faraway star, just as others before him had done.

But, several days later, Herschel noted that the object had traveled across the sky. Based on its movement, he concluded that the object was too close to Earth to be a star, therefore, he decided it must be a comet. William Herschel then presented his discovery and theory to the Royal Society.

It wasn’t until Mathematician, astronomer, and physicist Andres Johan Lexell studied the orbit of the object with great detail, that he calculated and revealed that the object was actually a planet¹. Lexell even revealed that the Uranus’s orbit suggested the existence of another undiscovered planet beyond it. This remarkable theory was proved true in 1846 when Neptune was discovered.

Having acknowledged Uranus as a planet, Herschel wanted to name it Georgium Sidus, or Georgian Star, after King George III. Unsurprisingly, the wider scientific community was not supportive. Instead, they named it Uranus after the figure in Greek mythology, who was both the father of Saturn and grandfather of Jupiter.

Six years later, in 1787, William Herschel discovered Titiana and Oberon, Uranus’s largest, and second largest moons, respectively.

The 1800s – Lassell Discovers Ariel and Umbriel

William Lassell was an English merchant who made his fortune as a beer brewer. He then used his riches to fuel his real passion, astronomy. Lassell built an observatory in his home, “starfield,” and in 1851, the “amateur” astronomer discovered Ariel and Umbriel, two more of Uranus’s moons.

Both Ariel and Umbriel were named by Sir John Herschel, William Herschel’s son, at Lassell’s request.

Uranus as seen on Voyager 2
Image Credit: NASA, Unsplash

The 1900s – Miranda, and Uranus’s Rings

The Dutch astronomer, a person who many consider to be the father of modern planetary science, Gerard P. Kuiper, discovered Miranda, another of Uranus’s moons, on February 16, 1948, from the McDonald Observatory in Texas. The small moon¹ is 1/7th the size of our moon. Yet, despite its size, Miranda is full of character and surprises. Miranda has giant canyons up to 23 times as deep as the Grand Canyon.

Almost three decades later in 1977, the Kuiper Airborne Observatory, named after Gerard Kuiper, and the Perth Observatory in Australia carried out observations that led to the discovery that Uranus, like its neighboring planet, Saturn, has rings¹.

Nasa’s Voyager 2 was the first, and so far the only, visitor to Uranus. Voyager 2 flew within 50,600¹ miles of Uranus’s outermost clouds and discovered 10 new moons and two new rings. Voyager also discovered that Uranus’s magnetic field is stronger than that of Saturn.

The 2000s – Hubble Space Telescope Photographs Uranus

In 2005 Nasa’s Hubble Space Telescope captured images of another pair of rings around Uranus and 2 more new moons. The small moons are named Mab and Cupid.

A year later scientists observed that Uranus’s rings are interestingly colored. Its outer ring appears blue, while its inner ring is colored red. This could be because the larger particles of the inner ring reflect more red light.

3D rendition of planet Uranus
Image Credit: 3dFLasH, Shutterstock

telescope divider 1 Interesting facts about Uranus

It rains diamonds on Uranus

Scientists have long theorized that the composition of Uranus, combined with its intense pressure and heat, may lead to the existence of diamond rain¹. The theory has been proven in lab experiments where nano-sized particles were made by directing powerful lasers at polystyrene. However, on Uranus, where the heat and pressure are continuous, the diamonds would probably be a lot larger!

Uranus Has a Unique Tilted Axis

If you think of the planets in our solar system like spinning tops, Uranus’s axis is the only one that doesn’t match. The planet seems to be sitting on its side, rolling around like a ball instead. Its 98º tilt causes the most extreme seasons of any other planet in our solar system. Dark winters¹ on Uranus last 21 years!  

One Uranian Year is 84 Earth Years

It takes 84 earth years for Uranus to complete one orbit around the sun. Because of its unique tilt, either one or the other of its poles face the sun for 42 years Earth years.

Uranus Holds the Record for the Coldest Planet in Our Solar System

Even though Neptune is further away from the sun than Uranus, temperatures on Uranus can dip to -371.2ºF¹. Scientists believe this has to do with Uranus’s uniquely tilted axis. Neptune also has more methane than Uranus, which could contribute to a slightly higher temperature.

Featured Image Credit: 24K Production, Shutterstock

About the Author Cheryl Regan

Cheryl is a freelance content and copywriter from the United Kingdom. Her interests include hiking and amateur astronomy but focuses her writing on gardening and photography. If she isn't writing she can be found curled up with a coffee and her pet cat.