An asteroid that struck the Earth between 3.25 and 3.5 billion years ago created an earthquake that shook the entire planet for half an hour.
Stanford researchers have measured the size of the asteroid at about 30 miles across, roughly as wide as the state of Rhode Island. The massive asteroid impacted the planet at 42,000 miles per hour. The sky burned red-hot following the impact. Oceans boiled, much of it streaming into the atmosphere. Tidal waves hundreds of feet high formed in much of the water that remained.
"[W]aves from the impact greatly exceeded the amplitudes of typical earthquake waves," researchers wrote in their research article published in journal G3.
Norman Sleep of Stanford University created the most detailed model ever created of the ancient impact.
The Barberton Greenstone Belt is one of the oldest rock formations on Earth. The feature is located in South Africa. Tiny spherules created in the impact were found in the layer corresponding to the ancient rock bed. Also present in the layer is the element iridium, which is common in meteorites, but extremely rare on Earth.
Geologists believe the impact occurred thousands of miles from the greenstone belt. The impact was so great it deformed the seabed and affected continental plates. As hot rocks thrown into the air and cooled in the atmosphere, it formed spheres of rocks that rained back to Earth, producing the spherules found in South Africa.
"There's widespread evidence that the asteroid's impact caused the ground to fail from earthquakes everywhere around the world," Sleep told the press.
Erosion has worn away most of the evidence from this ancient collision, hiding much of the evidence, geologists need to piece together information about the event.
Greenstone belts are found in various places around the world, including Canada, Australia and Madagascar. They are named for the distinctive green color of chlorite minerals that mark the features.
The Late Heavy Bombardment was a period in the history of ancient Earth when our planet was frequently bombarded by large asteroids. This era ended not long before this tremendous impact took place. Astronomers believe numerous other similar-sized objects also struck our home world during that period. Based on lunar craters, the Earth may have been struck by several objects capable of making craters as large as the United States. Around 22,000 objects struck our planet during that time, each large enough to completely destroy a city.
The asteroid that struck earth over three billion years ago is estimated to measure between 23 and 36 miles in diameter.
