Last month, the moon was pelted by two rogue space rocks that slammed into its surface within a day of each other, CNET reports.
The news comes from the European Space Agency (ESA), which unveiled a GIF showing the two events right before the total lunar eclipse of July 27-28.
According to the sources, the first of the two meteors struck the moon on July 17, with the other one coming in hot pursuit exactly a day later. The two meteoroids that landed on the lunar surface are thought to be “about the size of a walnut” and crashed in different regions of the moon, as seen in the short clip below.
Scientists speculate that the rogue meteors could have come from the Alpha Capricornid meteor shower, which usually begins around mid-July and continues until around August 10. As ESA points out, the Alpha Capricornids are leftover debris from comet 169P/NEAT, on whose “dusty” trail the Earth and the moon pass every year.
The violent encounter was picked up by the Moon Impacts Detection and Analysis System (MIDAS), which uses powerful telescopes equipped with high-sensitivity CCD video cameras to keep track of what happens on the lunar surface.
Despite being so tiny, the two meteors “thwacked into the moon with enough energy to produce a brilliant flash of light,” notes ESA. Both lunar flashes can be seen in the GIF, which edits the MIDAS footage to show the meteor impacts right after one another.
“On 17 July 2018, an ancient object from space impacted on the Moon with enough energy to produce a brilliant flash of light. A second flash lit up a different region almost exactly 24 hours later,” ESA officials wrote on Twitter on July 27.
On 17 July 2018, an ancient object from space impacted on the #Moon with enough energy to produce a brilliant flash of light. A second flash lit up a different region almost exactly 24 hours later.
— ESA (@esa) July 27, 2018
Such occurrences are known as “transient lunar phenomena” and are rigorously being tracked by MIDAS.
“By definition, these transient flashes are hard to study, and determining their cause remains a challenge,” explains the space agency.
All the more reason for MIDAS to keep its telescopes pointed at the moon and detect each piece of space rock that hits the lunar surface, even on its “darker faces,” ESA points out.
These are not to be confused with the dark side of the moon, which remains ever obscured to our sight because the moon is tidally locked and always faces Earth with the same side.
“By studying meteoroids on the moon, we can determine how many rocks impact it and how often, and from this we can infer the chance of impacts on Earth,” MIDAS scientist Jose Maria Madiedo said in a statement.