During a January 2019 lunar eclipse, an object hit the moon traveling at nearly 38,000 miles per hour. The resulting flash was part of an energy discharge equivalent to 1.65 US tons of TNT, with material ejected reaching temperature of 5400 degrees Celsius, about the same as the surface of the Sun.
The most recent lunar eclipse took place on 21 January 2019, with observers in North and South America and Western Europe enjoying the best view. At 0441 GMT, just after the total phase of the eclipse began, a flash was seen on the lunar surface. Widespread reports from amateur astronomers indicated the flash — attributed to a meteorite impact — was bright enough to be seen with the naked eye.
Madiedo and Ortiz operate the Moon Impacts Detection and Analysis System (MIDAS), using eight telescopes in south of Spain to monitor the lunar surface. The impact flash lasted 0.28 seconds and is the first ever filmed during a lunar eclipse, despite a number of earlier attempts. …
Unlike the Earth, the Moon has no atmosphere to protect it and so even small rocks can hit its surface. Since these impacts take place at huge speeds, the rocks are instantaneously vaporised at the impact site, producing an expanding plume of debris whose glow can be detected from our planet as short-duration flashes.
MIDAS telescopes observed the impact flash at multiple wavelengths (different colours of light), improving the analysis of the event. Madiedo and Ortiz conclude that the incoming rock had a mass of 45kg, measured 30 to 60 centimetres across, and hit the surface at 61,000 kilometres an hour. The impact site is close to the crater Lagrange H, near the west-south-west portion of the lunar limb.
The two scientists assess the impact energy as equivalent to 1.5 tonnes of TNT, enough to create a crater up to 15 metres across, or about the size of two double decker buses side by side. The debris ejected is estimated to have reached a peak temperature of 5400 degrees Celsius, roughly the same as the surface of the Sun.
This was a rare event to occur at the time of an eclipse. The density and frequency of space rocks hitting the moon is an important consideration for missions that visit as well as dreams of permanent moon colonies. Impacts like this explain why moon colonies may need to be built far underground. How far is an interesting question.
.. If we imagine a typical large musket ball with a mass of 28 g, we could imagine 100,000 of them rain down on the Moon each day.
If the distribution of sizes includes a lot of smaller marble sized rocks instead of musket-sized, the number per area would increase, one assumes.
Is the mass of the moon increasing?
I’ve found no answer to this question so far. The mass of the Moon is 7.4 × 10 m^22 kg, approximately 1/80 the mass of the Earth according to a text on the Foundations of Astronomy. The physics Fact book site gives several different answers ranging from 7.34 to 7.475 × 10 m^22 kg from different sources:
Is the mass of the earth increasing?
No, overall, the Earth’s mass is decreasing.
According to some calculations, the Earth is losing 50,000 metric tons of mass every single year, even though an extra 40,000 metric tons of space dust converge onto the Earth’s gravity well, it’s still losing weight. … The biggest mass loss comes from escaped hydrogen and helium, which escape with 95,000 metric tons of mass and 1,600 metric tons respectively. These elements are too light to stay permanently in the gravity well, so they tend to escape into space.
This is nothing to be concerned about, however. Due to the massive amount of these gasses in Earth’s atmosphere, it will take trillions of years for them to be depleted.