Compared to Earth, not much happens on the Moon. Where our planet’s surface is an impressive mix of wind-swept plains, ice-carved gorges, and volcanic mountain peaks, the Moon’s surface has impact craters. Many impact craters. Without the dynamic geological and atmospheric processes that keep the face of our Earth relatively fresh, Earth’s satellite has been battered and scarred by cosmic shrapnel for billions of years. But that’s not the whole old story. The moon’s bombardment continues and it’s constantly raining debris.

Most are invisible, but a particularly bright shock flash was captured by astronomer Daichi Fuji of the Hiratsuka City Museum using lunar observation equipment at his home in Hiratsuka in late February. Most objects in space are too small and dark to be seen when approaching the Moon, so we only know that they hit it from a flash. To catch one, you have to look for the right time — so astronomers hoping to see the effect set up tracking equipment to make sure they didn’t miss the moment.

“I’ve managed to record the largest moon collision flare in the entire history of my observations!” Fuji wrote this on Twitter.

“This is a photo of the Moon impact flash from my home in Hiratsuka (played at real speed) on February 23, 2023 at 20:14:30.8 pm. It was a massive flash that continued to shine for over an hour second. The moon has no atmosphere. Meteors and fireballs cannot be seen and glow when a crater is formed.’

In fact, it should come as no surprise that the Moon is under constant bombardment. Outer space is littered with small stones, many of which fall into our planet’s atmosphere every day. A study conducted in 2020 found that about 17,600 stones weighing more than 50 grams fall each year.

The reason they’re usually not news is because the thick layer of gas they have to pass through often deprives them of any splendor. Meteorites falling into the Earth’s atmosphere tend to burn or explode without our knowledge; What doesn’t evaporate eventually falls to the ground as much smaller pieces of rock or dust and doesn’t leave much of a trace, let alone an impact crater. The moon has no atmosphere and meteors fly fast. Imagine a stone hitting Earth’s atmosphere at a speed of up to 72 kilometers (45 miles) per second. Anything that hits the surface of the Moon will hit hard.

Most of what goes in will be quite small. We can’t even see it with a telescope. A few years ago, however, a project by the European Space Agency to study the effects of the Moon with more powerful technology revealed that objects large enough to cause a flare hit the Moon an average of eight times per hour.

Among these frequent collisions will be the accidental collision of a larger object that can be seen with equipment in the backyard. It does not have to be a very large stone. In 2019, an astronomer caught the moon’s shock glow during a lunar eclipse; The estimated size of this stone was about 2 kilograms (4.4 lb), about the size of a soccer ball. We won’t know more about Fujii’s influence until more observations are made. The size of the crater will help astronomers calculate the size and velocity of the object that caused it; This information will help us better characterize the continuous rain of stones hitting our satellite and the evolution of its rocky, rough surface.