Sunspot AR3245 is splitting in two. This 24-hour movie from NASA’s Solar Dynamics Observatory shows the sunspot’s primary core dividing like a eukaryotic cell as it turns toward Earth.
The bright, linear gap between the sunspot’s two halves is known as a “light bridge.” It measures 20,000 km from end to end.
The nature of light bridges is not fully understood. They often herald the break-up of a sunspot, with jets of plasma shooting up from the chasm as the sunspot decays. Some research suggests that magnetic fields at the base of a light bridge are busy cross-crossing and reconnecting–the same explosive process that sparks solar flares.
