Pluto still revolves around the sun

Science in dialogue

Why does Uranus rotate differently than all other planets in our solar system?

Nobody knows for sure, because the question of how Uranus rotates was decided around four and a half billion years ago. At that time, our solar system was created - from a large cloud of gas and dust.

This cloud was already turning. The gas and dust particles in it were not evenly distributed. Due to the attraction of mass (gravitation), particles attracted each other and condensed more and more. In this way, various clumps of particles of different sizes emerged from the cloud, all of which turned as the cloud had done. The fact that in our solar system today all planets orbit the sun in the same direction is related to the fact that they all emerged from the same cloud. It also goes back to the fact that the planets rotate like tops around themselves.

However, apart from the sun, which was formed in the center of the cloud, and the eight planets with their moons as we know them today, there were initially many other clumps of particles in the solar system. And there were always clashes. In such a collision, the bodies involved can tip over - and thus also change their direction of rotation.

Scientists suspect that Uranus also experienced collisions with other lumps of particles in the course of its formation. Its axis of rotation was tilted by almost 100 degrees. The axis around which Uranus rotates today is therefore almost in the plane of the orbit, so that the planet "rolls" backwards along its orbit around the sun.

The question was answered by Dr. Carolin Liefke from the House of Astronomy in Heidelberg.

(Editor WiD: urs)