Universal rotation curve

A universal rotation curve is a graph which shows how fast something is spinning. To understand why this is important, you need to know that everything in the Universe is always spinning! From planets to stars, and all sorts of other things, they all have some kind of rotation (spinning). The universal rotation curve is a graph which represents this spinning in a visual way. It shows how fast things are spinning in different parts of the Universe, like near a star or in the outer reaches of a galaxy. By looking at the rotation curve, scientists can learn a lot about the objects they're studying, like how dense they are and what they're made of. So it's an important tool for astronomers.