Robert’s Out of This World Space Odyssey: Uranus, Haha, You Said Uranus

You better grab a parka and some hot chocolate, because we have arrived at the ice giants.

At a distance of 1,784,860,000 miles (2,872,460,000 kilometers) from the sun (a distance that takes light almost 3 hours to travel), Uranus is orbiting though the suburbs of our galaxy. Discovered by astronomer William Herschel in 1781, Uranus is the first planet discovered since ancient times.

When you talk about the orbit of Uranus around the sun, you are starting to really talk about a distance to travel. One year on Uranus (a full orbit around the sun) takes 30,685 Earth days or a little more than 84 Earth years. Most people don’t even live that long. One day on Uranus is a little faster than an Earth day, only taking 17 hours 14 minutes. What is fun about the rotation of Uranus around its axis is that this plant basically rotates on its side. Scientists believe during formation something about the size of Earth smacked into Uranus and knocked it onto its side. Being tipped on the side means that for the majority of the Uranian year only the poles receive light and leave the rest of the planet in the dark. To make the rotation even better, like Venus, Uranus rotates retrograde (east to west) – you know, just to be different.

Uranus is a ball of gas and liquid about four times the size of Earth. Due to its distance from us, there is a lot of speculation about the composition of Uranus. It may have a solid rocky core, about the size of Earth, surrounded by a liquid sea full of dissolved ammonia. Above this sea would be layers of thick water clouds stocked full of frozen ammonia crystals. Topping the atmosphere off are blue-green clouds comprised of frozen methane crystals. Similar to the other gas giants, Uranus is probably a planet covered in high winds and violent storms.

William Shakespeare wrote in a Midsummer Night’s Dream, “Sweet Moon, I thank thee for thy sunny beams; I thank thee, Moon, for shining now so bright.” Astronomers liked that line, so they decided to name the moons of Uranus after Shakespeare’s characters. All of the moons orbit the planet in the same way it rotates (the orbits look like they go up and over then back under the planet, versus around it like our moon). Oberon and Titania are the largest moons (they are also the king and queen of the fairies). Miranda is the smallest and innermost moon and is also the most unique moon in the galaxy. It has a cavern 12 times deeper than the Grand Canyon. Uranus has 27 identified moons and more are expected to be found.


We know there should be more moons because something needs to explain the extra gravity being provided to help hold together Uranus’ rings. Yup, Uranus has rings too. An inner ring system found in 1977 and an outer ring system found in 2003. In 2007 it was observed that the outer rings are really brightly colored. See, look, 2007 – that is not long ago. There is still so much to learn about the planets!