Shortly after 4 billion years ago, the moon had formed from a debris disc, releasing water vapor and other volatile gases in bulk. The second event occurred about 3.5 billion years ago when volcanic activity peaked on the moon.
In both cases, the release of these volatile gases would have created liquid pools of water on the surface and a dense atmosphere could remain in place for millions of years. It also likely had a magnetic field that could protect any life on the surface from solar wind, a deadly stream of charged particles streaming out of the sun.
Today the moon has no atmosphere, but a very thin layer of gases, including sodium and potassium, that try to act as an atmosphere.
"It looks like this as if the moon was habitable at the time, "said study author Dirk Schulze-Makuch, an astrobiologist at Washington State University, billions of years ago. "There could actually have been microbes that thrive in water basins on the moon until the surface is dry and dead."
But what would life have looked like if it existed on the Moon and how it came into being?
On Earth, the earliest evidence of life on cyanobacteria fossils can be traced between 3.5 billion and 3.8 billion years ago. Cyanobacteria are microscopic single-celled organisms that produce oxygen through photosynthesis.
The ingredients for life have been found in meteorites before, and it is believed that meteorites could have helped to bring water to the earth in the early time of its formation. The researchers for this study suggest that in the early days of our solar system, it is possible that meteorites that have come in contact with the Earth and have "blasted from their surface" could also have landed on the moon.
This was common in the early solar system when, according to the study, it came to huge collisions and the transfer of meteorites between planets.
If so, the meteorites might have carried microbes to the moon, and these microbes might have lived in water basins on the surface.
"If liquid water and a significant atmosphere were present on the early moon for a long time, we would think that the lunar surface was at least temporarily habitable," said Schulze-Makuch in a statement.
Now the moon is in Essentially dead and dry its surface covered with dust. But as future missions return to the moon, researchers believe that taking samples from areas that are at the height of volcanic activity could provide evidence of water or life.
Experiments simulating conditions on the moon between 3 billion and 4 billion years ago could, according to the study, also be carried out in laboratories on Earth or the International Space Station to see if microbes could survive.