A ghostly face has been spotted in a volcano seen from space.
Trou au Natron is a deep crater in the north-central African country of Chad.
It is part of the Tibesti Mountains, a chain of volcanic formations in central Sahara.
The crater is filled with natron, a naturally occurring mixture of sodium carbonate decahydrate and around 17% sodium bicarbonate.
Small quantities of sodium chloride and sodium sulfate are also found.
Natron, which gives the volcanic pit its name, was used by the ancient Egyptians for mummification purposes.
The image of the volcano’s face – made up of two eyes and a nose – was taken on board the International Space Station.
The photo was shared by NASA Earth Observatory on 31 October as their ‘Image of the day’.
A NASA spokesperson said: “The edge of the ‘face’ is partly formed by shadows cast by the rim of a caldera.
“A type of volcanic crater formed after an explosive eruption or the collapse of the surface into a partially-emptied magma chamber.
“The ‘eyes’ and ‘nose’ are cinder cones – steep conical hills built around volcanic vents.
“The cinder cones are thought to be relatively young in geological terms, likely forming within the past few million years and possibly as recently as the past few thousand years.
“The white area around the ‘mouth’ is a mineral crust made of a salt known as natron.
“It forms as hot spring water pools on the surface and evaporates, and mineral-rich steam rises from the surface of the geothermally active area.”
