A few billion years ago, the moon looked quite different. It was three times closer to Earth, so would have looked much bigger in the night sky.
And now we know it also had a visible atmosphere – one that has pretty much disappeared today.
Scientists have just discovered that dramatic volcanic eruptions on the moon’s surface created an atmosphere that lasted for around 70 million years.
Testing lunar samples collected by the Apollo astronauts back in the 1970s with more advanced modern instruments showed when the volcanic eruptions took place and what sort of gases the mountains spewed.
And now, scientists from the Nasa Marshall Space Flight Centre and the Lunar and Planetary Institute have used that information to calculate where those gases ended up.
Between three and four billion years ago, two volcanic eruptions flooded craters on the moon with lava. This magma released trillions of tonnes of gas as it flowed.
And since the gases were being produced faster than they could escape into space, an atmosphere was formed.
But what does this news mean for those studying our rocky neighbour?
“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 co-author Doctor David Kring, of the Lunar and Planetary Institute.
Some of these ancient gases have ended up at the moon’s poles, and if we found them, could be used in future space missions as fuel and could tell us more about the early years of both the moon and our own planet.
Their paper was published in the journal Earth and Planetary Science Letters and can be read here.