- Asteroid influences on Earth are hidden by erosion, but the moon holds a pristine record of them.
- Scientists dated 111 major craters on the moon to reconstruct the Earth's history of consequence over the last 1 billion years.
- The team discovered that major asteroid strikes were 2.6 times more common over the last 300 million years of that period.
- An animation illustrates the effect data with light and sound.
The moon has hidden a great secret on Earth in plain sight.
Evidence of old asteroid strikes is hard to find on our planet. In fact, fewer than 200 craters are known to science. The commonly understood reason for this has been that the Earth quickly erodes, buryes and otherwise hides even large impact sites.
However, the moon acts as a time capsule because it does not have air, water or active geology, so its craters do not disappear. And it happens right next to our planet, which means that what happened to the moon reflects what has also happened to Earth.
So a new study released this week in the journal Science took a look at the biggest lunar craters. By counting and dating such sites, the researchers suggest that an approximate history of asteroid strikes on Earth can be reconstructed.
"The moon is like a time capsule that helps us understand the earth," said William Bottke, a space researcher at the Southwest Research Institute, in a press release on the new research. "We found out that the moon shared a similar bombardment story, which meant that the response to the Earth's speed of impact stared at everyone in the face."
Deleting Early Assumptions about Earth's Impact History
The research team behind the work studied very detailed images of the moon and thermal data recorded by NASA's Lunar Reconnaissance Orbiter (LRO) to derive the largest crater age. When their analysis was completed, the 111 large sites had over one billion years.
The team's results indicate that the moon has fewer craters left by large strikes in the oldest 700 million years of that period, while large strikes were about 260% more frequent in the latter third.
This led the researchers to conclude that wind and water on Earth probably did not hide as many large sites as scientists who previously believed.
"The earth has fewer older craters on stable terrain, not because of erosion, but because the impact was lower than 290 million years ago," Bottke said in the release.
Read more : How big asteroids must be to destroy a city, state, country or planet
Bottke and his colleagues do not suggest that their discoveries mean we should worry about any huge asteroid strikes are coming soon. Instead, the upticket may have been a temporary wave driven by the "break of one or more major asteroids in the inner and / or central head asteroid bands," they wrote.
Work must be useful for scientists trying to understand the history of the earth and its complex relationship with life.
"Our results also impact on the history of life, which is characterized by extinction events and rapid development of new species," said Bottke. "Although the forces driving these events are complicated, asteroid effects have probably played a role in this ongoing story."
See the last 1 billion years of great moon asteroid strikes
The researchers at the Southwest Research Institute gave 1.3 billion years worth of lunar impact data to System Sounds animators that compressed this story to about one minute of film (of which one is not shown here).
The animation above illustrates 111 of the lunar major battlegrounds as sound and color, and in the order they appeared. Smaller craters are represented by higher and quieter sounds, while the largest are higher and lower.
In the last third of the video you will notice that there is an increase in lower and higher sounds.