The picture is of Europe and Africa when the sun is setting. Half of the picture is in night. The bright dots you see are the cities lights.

The top part of Africa is the Sahara Desert. Note that the lights are already on in Holland, Paris, and Barcelona, and that's it's still daylight in Dublin, London, Lisbon, and Madrid.

The sun is still shining on the Strait of Gibraltar. The Mediterranean Sea is already in darkness. In the middle of the Atlantic Ocean you can see the Azores Islands; below them to the right are the Madeira Islands; a bit below are the Canary Islands; and further south, close to the farthest western point of Africa, are the Cape Verde Islands.

Note that the Sahara is huge and can be seen clearly both during Daytime and night time.