When you’re a youngster in elementary school learning about the solar system, you discover Uranus. This is monumental. There’s so many puns to be had. So many, in fact, my grade school teacher forced us to call it “YOUR-en-us.” She wasn’t much for jokes, I guess.
And while the planet’s name is burned into your brain on day one, you never actually learn a very important characteristic of Uranus: why it tilts on its side as it rotates around the sun. The strange anomaly causes Uranus to produce irregular magnetic fields and its rings to revolve vertically instead of horizontally, like Saturn. Astronomers have had theories as to why, but nothing had been confirmed.
Now, new research from the Astrophysical Journal suggests Uranus was hit by a planet roughly two times the size of Earth, causing its planetary abnormalities. The collision likely happened long ago and massively changed the planet, explaining why Uranus is colder than the farther-out Neptune. This has been suggested before, but the evidence supplied by researchers furthers the hypothesis more than we’ve heard previously.
The object [to strike Uranus], according to the research, is likely closer to two Earth masses, as this would have kicked up more of the gas and dust that went on to form the inner Uranian moons. Uranus has 27 moons, but 13 of them are considered “inner” moons. Some of the mass from the planet would have been incorporated into Uranus, some went into the moons, and the rest possibly escaped the system entirely.
So now you have at least some explanation for the oddities of Uranus. Its other mysteries will probably not be solved in our lifetime, but at least now you know why it’s tilted just so. And yes, class, you may now say Uranus however you want to make yourself giggle.