Saturn: Mysterious shadows appear on planet's rings

Nasa has captured a picture of Saturn's mysterious 'spokes' on its rings.

It's quite a rare phenomenon, which can only be seen for two or three Saturn rotations - which is around 30 hours.

Because Saturn is so far away, it takes a long time - and a lot of effort - to capture the picture.

Although they might look quite small compared to Saturn, the 'spokes' length and width are longer than Earth's diameter.

The diameter is the distance right across the middle of a circle or sphere.

Nasa calls the shapes 'spokes', like those on a bike wheel. They look like shadows on both sides of the planet.

Scientists aren't quite sure how they form yet, but one theory is that it's got something to do with Saturn's magnetic field.

Scientists at Nasa think activity from the sun with Saturn's magnetic field, create the mysterious shapes.

We're also likely to see more of this soon. Nasa scientist Amy Simon says "we are heading towards Saturn equinox, when we'd expect maximum spoke activity, with higher frequency and darker spokes appearing over the next few years."

The Hubble Telescope, which is a huge telescope that can look deep into space - is going to be keeping a close eye on the spokes to try and unravel the mystery.

Our magnetic field on Earth can make some interesting shapes too. You might have heard of Aurora Borealis - also known as the Northern Lights.

They can be seen when light particles from the sun bump into the planet's atmosphere and are pushed to the north and south poles, because of the Earth's magnetic field.

This can create beautiful shapes in the sky.