Why is Uranus tipped on its side? (Beginner)

Could you please explain why Uranus is laying/spinning on its side?

The reason for Uranus' tilt is still a big mystery. Most astronomers do not believe that the planet formed this way and was instead knocked on its side by an impact in its early history. The collision could have been with any object large enough to cause the tilt. However there are still a few questions this theory does not answer. For instance, why does Uranus still have a nearly circular orbit like most of the other planets if it was knocked so hard? And if its moons were formed before the collision, why are their orbits also so nearly circular?

About the Author

Sabrina Stierwalt

Sabrina Stierwalt

Sabrina was a graduate student at Cornell until 2009 when she moved to Los Angeles to become a researcher at Caltech. She now studies galaxy mergers at the University of Virginia and the National Radio Astronomy Observatory in Charlottesville. You can also find her answering science questions in her weekly podcast as Everyday Einstein.

 Twitter: @galaxygirlguru
 Website: www.astro.virginia.edu/~srs5vn

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