Hey, Sky Fans. I hope you had a great Christmas, and some wonderful time with your family yesterday. If you’re celebrating Kwanzaa, I hope you have a great holiday, and thanks for taking the time out of your day.
Quick, think of all the things you know about Uranus off the top of your head. I’ll give you a second.
Let’s see: Uranus is the 7th planet from the Sun, the third biggest, takes 84 Earth years to go around once, has a thin ring system, and orbits on its side. Was I close?
Yeah, you know, it’s funny. Not a lot of people spend a lot of time talking about the 7th planet. It doesn’t get a lot of news. Though earlier this year, there was some talk that there was more going on there than there seemed to be when Voyager 2 came within about a fifth of the distance from the Earth to the Moon in 1986. Back then, astronomers were disappointed to find a very flat, mostly featureless cloud-covered planet, and Voyager sped off to Neptune.
As far as its moons go, can you name more than one or two? I still remember a poster I had hanging on my bedroom wall, a map of the solar system, that showed Uranus with five moons.
Uranus has 27 moons, wow, and the more I read about them to research this post, the more interesting I found them, and I started to wonder if maybe we, as a group of astronomy fans, are really missing out by not thinking more about them. For the third night of Hanukkah, this brings us to number 6 on our list of 2016’s best moons.
I’ll just come right out with it: Uranus’s moons are really interesting. There’s 27 of them, split into groups. Of those, only five manage to skirt inside the limits of being big enough to hold themselves together as spheres. Those five—Titania, Oberon, Ariel, Umbirel, and Miranda—are fairly small, though. Combined, they’re all smaller than than Neptune’s moon Triton. You’re not the only one who thinks it’s easy to confuse the names of Titania, Triton, and Saturn’s Titan. Some moons are lumpy, some orbit backward, some help keep the rings together, and all of them are named after William Shakespeare or Alexander Pope characters. Some even have U-shaped orbits (they’re unstable).
Miranda, which was discovered in 1948 by Gerard Kuiper (he, not the former San Francisco Giants slugger Duane, is also the name behind the Kuiper Belt), is the smallest of this group of Uranus’s big moons, only about 300 miles across. It’s the 13th most distant of Uranus’s moons, but the closest of the big moons. It’s so close that it finishes one orbit around Uranus in about 36 Earth hours. For comparison, tiny Cordelia is the closest-in of all of Uranus’s moons, and finishes one orbit in just just a little over 8 Earth hours. That’s amazing for such a big planet.
What strikes me most of all is it’s landscape. As I flipped through photos from Voyager 2, picture after picture, like when I was reading about Saturn 35 years ago, it was icy cliff upon icy canyon. There’s a lot of ice. Some of Miranda’s surface is old, some young. There’s rocks and cliffs and canyons. It looks like it was made from bits and pieces, leftover spare parts stuck together. It’s really an incredible place. That, like a good movie, or bowl of soup, left me wanting more. You can see some of these amazing things in this photo, particularly toward the lower right.
Here’s to number 6 on our list, Uranus’s moon Miranda, for making me feel like a kid again and inspiring me to go back and learn more about all of Uranus’s moons. I hope you will, too. Clear skies, everyone!