tech2 News StaffJan 21, 2019 17:28:20 IST
The moon appears to have been hiding a secret in plain sight about the Earth's recent history.
Asteroid strikes have been always been considered few and far between on Earth, with fewer than 200 craters in total known by scientists to exist. Researchers have justified this with the Earth's quick changes in landscape from erosion, burying or other geological factors that may help hide impact sites.
With air, water or much geological activity, the moon, however, is a lot like a time capsule. Being in close proximity within the solar system, impacts on the moon should reflect incidents that also affected Earth.
In a new study, researchers have looked at the biggest craters on the moon — counting and dating their impact sites to approximate when the asteroid might have struck the moon and/or Earth.
"The moon is like a time capsule, helping us understand the Earth," William Bottke, a space scientist at the Southwest Research Institute, said in a press release. "We found that the moon shared a similar bombardment history, which meant the answer to Earth's impact rate was staring everyone right in the face."
The team of researchers analyzed images taken by NASA's Lunar Reconnaissance Orbiter (LRO) to gauge how old these craters are. The study showed a total of 111 major impact sites over a period of 1 billion years.
Their findings were that the biggest strikes over the first 700 million years of those billion left fewer craters, but big strikes were 260 percent more frequent in the last 300 million years. The team also found that wind and water on Earth probably didn't contribute to hiding as many impact sites as early astronomers had assumed and theorized.
"Earth has fewer older craters on stable terrains — not because of erosion, but because the impact rate was lower prior to 290 million years ago," Bottke said in the release.
The surge is probably a temporary one, driven by the "breakup of one or more large asteroids in the inner and/or central main asteroid belt," the study reads.
The findings could be an important step in the astronomy community's understanding of Earth's history and its complex link with life.
"Our findings also have implications for the history of life, which is punctuated by extinction events and rapid evolution of new species," Bottke said. "Though the forces driving these events are complicated, asteroid impacts have surely played a role in this ongoing saga."
The team also put together 1.3 billion years' worth of impact data from the moon's surface with help from animators in a minute-long musical treat. The animation illustrates 111 of the moon's larger impact craters as sound and colour — in the same order that they took place in.
While the smaller impacts are given a higher-pitched, quieter sound, the bigger impacts are louder and lower-pitched.
In the last third of the video, you may also pick up on the abundance of lower, louder sounds — much the last 300 million years on Earth.
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