Sun

This image shows the Sun in white light (the visible spectral range) with several active regions on its surface, the so-called photosphere. Sunspots are caused by strong magnetic fields that locally inhibit the transport of energy from the Sun’s interior. As a result they are a few thousand degrees cooler than their surroundings and appear noticeably darker by comparison. Typical is the structure of a dark umbra and a surrounding, finely structured penumbra.

The most conspicuous group of spots near the centre of the image reaches an extent of up to about 100,000 kilometres — roughly 8 times the diameter of the Earth. Such complex regions are often associated with increased activity and can cause energetic eruptions such as solar flares or coronal mass ejections.

The surrounding smaller spot groups also show that the Sun is currently in an active phase of its roughly eleven-year cycle. The structure of these regions is dynamic and can change noticeably within a few days.

The image was taken in white light and colour-processed to better reveal fine details.