Astronomy Picture of the Day

Explanation: A tantalizing glimpse inside this dome was captured after sunset at the mountain top Pic Du Midi Observatory in the French Pyrenees. But while most are just beginning their work at sunset, this observatory's day was done. The instrument looming within is CLIMSO (for Christian Latouche IMageur Solaire), dedicated to exploring dynamic phenomena across the surface and atmosphere of the Sun. To image the solar atmosphere or corona, CLIMSO uses coronagraphs. Developed by French astronomer Bernard Lyot in the 1930s, coronagraphs block light from the centre of the telescope beam to create an artificial solar eclipse and allow a continuous view of the solar corona. In this surreal twilight scene above a sea of clouds, the dome's interior was revealed by the single, long exposure as the open slit rotated across the field of view.