The latest study of NASA has revealed that the Moon had an atmosphere about three to four billion years ago at the time when intense volcanic eruptions spewed gases above the surface faster than they could escape to space.
Dark surfaces of volcanic basalt can still be easily seen when one looks up at the Moon.
Those seas of basalt, known as maria, erupted while the interior of the Moon was still hot and generating magmatic plumes that sometimes breached the lunar surface and flowed for hundreds of kilometers.
Those magmas carried gas components, such as carbon monoxide, the ingredients for water, sulfur, and other volatile species, analyses of the lunar samples indicate.
The amounts of gases rose from the erupting lavas as they flowed over the surface and showed those gases accumulated around the Moon to form a transient atmosphere. It has been calculated by the researchers from the NASA and Lunar and Planetary Institute in the US.
About 3.5 billion years ago, the atmosphere was thickest during the peak in volcanic activity and when it was created, it would have persisted for about 70 million years before being lost to space.
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The two largest pulses of gases were produced when lava seas filled the Imbrium and Serenitatis basins about 3.5 and 3.8 billion years ago, respectively.
The astronauts of the Apollo 15 and 17 missions explored the margins of those lava seas. They collected the samples which not only provided the ages of the eruptions, but also contained evidence of the gases produced from the erupting lunar lavas.
Debra H Needham, Research Scientist of NASA Marshall Space Flight Center said, “The total amount of water released during the emplacement of the mare basalts is nearly twice the volume of water in Lake Tahoe.”
“Although much of this vapor would have been lost to space, a significant fraction may have made its way to the lunar poles. This means some of the lunar polar volatiles we see at the lunar poles may have originated inside the Moon,” the research scientist added.
“This work dramatically changes our view of the Moon from an airless rocky body to one that used to be surrounded by an atmosphere more prevalent than that surrounding Mars today,” said David A Kring, from LPI.
“When the Moon had that atmosphere, it was nearly three times closer to Earth than it is today and would have appeared nearly three times larger in the sky,” he added.
(With PTI inputs)
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