© olcano.oregonstate.edu/NASA
There are many volcanic features on the lunar surface. In fact, the dark lunar maria that you can see when there is a full Moon are massive, generally level deposits of basalt, a volcanic rock. The Gruithuisen Domes (shown by the black arrows in this Apollo 15 picture) are unusual silica-rich volcanoes.
There are many volcanic features on the lunar surface. In fact, the dark lunar maria that you can see when there is a full Moon are massive, generally level deposits of basalt, a volcanic rock. The Gruithuisen Domes (shown by the black arrows in this Apollo 15 picture) are unusual silica-rich volcanoes.
Three to four billion years ago, the giant volcanic eruptions that created the Man in the Moon also gave the Moon an atmosphere, scientists say.
That's because volcanic eruptions release gases, and a new study, published online in Earth and Planetary Science Letters, calculates that these gases would have accumulated more quickly than they could escape into space, even under the Moon's low gravity.
The exact composition of that ancient atmosphere isn't completely known, but it would have included carbon dioxide, water, hydrogen, and sulfur, says David Kring of the Lunar and Planetary Institute in Houston, Texas. And there would have been enough of these gases to raise the surface pressure about 50% higher than on present-day Mars, about 1% of Earth's at sea level.
The research was based on prior studies that reanalysed volcanic rocks brought back by Apollo astronauts. These studies had concluded that the magma from which these rocks solidified contained substantially larger quantities of gases than had previously been believed. Kring's brainstorm was to wonder where those gases had gone.
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