Uranus

A lot of the conversation that takes place about Uranus is marked by terms like “the least” and “less dense” and “less massive.” In comparison to other planets in our solar system, it comes up a bit like a younger brother; always falling short in comparison to older siblings. But, like the younger brother often does, Uranus surprises observers with quite a few features that leave scientists scrambling for their thinking caps.

A Look at Uranus

Uranus is remarkable for a lot of reasons, not the least of which because it is the first new planet discovered in the modern age. Ancient observers knew about Uranus, one of the planets that can be seen with the naked eye, but due to its slow movement and dim appearance it was always considered a comet or far off star rather than a relatively close neighbour to our home in space. On March 13, 1781 Sir William Herschel made a notation of the planet and is credited with its discovery—but it was a long road from his first notation, which clearly labelled Uranus (as of yet unnamed) as a comet, to a planet. Herschel’s comet explanation quickly met with critics who pointed out that no observable tail, it’s relatively round trek through the sky and its distance—estimated at three times further from Earth than any as of yet observed comet—all pointed to a different possibility. By 1783 Herschel finally accepted what others had already decided, that the object was indeed a planet, and the naming process began.

Its discoverer wanted to call it “George’s Star” after the then-monarch King George III, but Berlin astronomer Johann Elert Bode suggested Uranus, the sky god that was the father of Saturn, as Saturn was the father of Jupiter. The name became universally accepted by 1850.

Uranus, Ice Giant

Uranus is, technically, one of the gas giants in our solar system. It is not a terrestrial planet (rock-based), but because it has a different composition than Jupiter and Saturn, so scientists created a new category for it and Neptune, “Ice Giants.”

Despite the name Uranus is not, as one might imagine, a giant ball of ice. In fact its surface is thought to be liquid rather than solid, a water-ammonia ocean that blends so closely with the gaseous atmosphere that scientist had to pick a near-arbitrary point to call “surface” so that they could discuss it separately from the “atmosphere” of the planet.

The uniqueness of Uranus does not stop there. Unlike the rest of the planets in our solar system Uranus does not “spin like a top” on its axis, but rather rolls much like a football on a spit would. It’s extreme axial tilt of 98 degrees is thought to have been caused by an impact from an Earth sized protoplanet in the early days of the universe, which may also explain why the planet radiates much less internal energy than other planets; the impact caused most of the internal radiation to shunt out into space. Other theories include some layer that keeps the heat from reaching the surface, but in plain fact, scientists just don’t know. Another feature of the tilt is that the poles spend more time facing the sun than the equator (yet despite this the equator is still hotter than the poles, reason unknown) but each spends 42 years in darkness followed by 42 years of light as Uranus travels its 84 Earth-year trip around the sun.

Uranus has a ring system that is fairly faint; Herschel mentioned it, but then two hundred years passed before it was observed again. The ring system has some company around Uranus, as it has a satellite system of 27 moons, most named after Shakespearean characters.

Final Thoughts

The cyan disk in the sky that can be observed with amateur telescopes continues to fascinate and puzzle scientists. Voyager 2 got a good look at the planet in 1986, but it is unlikely we will get that close to Uranus for some time to come.

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• All About The Earth
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• Jupiter
• Mars
• Neptune
• Planet Mercury
• Planet Venus
• Planets Outside the Solar System
• Pluto
• Saturn