Planetary scientists noticed that Uranus is very different than other solar system planets. First, it spins on its side, rather than rotating on an axis like that of other planets. Second, and even stranger, its many moons revolve around the planet sideways.

What caused this icy planet’s strange state?

Planetary scientists had a theory. They thought that, in the early solar system, a smaller Uranus may have crashed into a roaming ball of ice. The two bodies combined with each other, forming the Uranus we know today. In the early 1990s, researchers were able to model and confirm this theory - after a crash

But a new model, produced by Japanese astronomers, takes it a step further. They wanted to observe what happens with higher quality, modern simulations.

They found three interesting things:

1. The impact of the two bodies made of ice would create clouds of water vapor, hydrogen gas and helium gas. These clouds would then cool down and condense into small ice particles. Those particles orbited Uranus, forming moonlets - small moons.

2. When simulating the collision of 10,000 icy moonlets, several large moons appeared. Four of them even had the same orbiting patterns as four of Uranus’ real moons!

3. The only way this could happen is if the bodies were mostly made of ice. Only ice has the properties that allow for moonlets to form.

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This simulation further confirms the original finding in the 1990s. But it also provides an explanation for Uranus’ moons - a big step forward! However, planetary scientists are not satisfied with simulations that look back. They want to develop one that predicts.

For example, a new simulation could determine what substances resulted from the collision. With it and a sample of Uranus’ surface, we can compare the simulation’s results with the reality. If they match, scientists could use this model to predict the compositions of planets!  Valuable knowledge when exploring space!

Citation:https://www.popsci.com/story/space/why-uranus-spins-sideways/