And the damage from it? Apocalyptic.
"The impact would have triggered earthquakes orders of magnitude greater than terrestrial earthquakes. It would have caused huge tsunamis and would have made cliffs crumble," said Andrew Glikson, of the Australian National University (ANU) Planetary Institute.
The asteroid, which is thought to have hit the Earth 3.46 billion years ago, is estimated to have been huge -- 12 to 18 miles (20 to 30 kilometers) wide -- and its impact would have been felt around the globe.
Glikson and his team are basing their assessment on the discovery of tiny glass beads called spherules. They materialized from vaporized material caused by the asteroid's impact.
The asteroid's possible size was determined by analyzing the size of the spherules, Glikson told CNN.
It means the asteroid was bigger than the one that is thought to have wiped out the dinosaurs. It hit Earth 66 million years ago.
Glikson says it's impossible to tell where it would have struck, but it would have formed a crater hundreds of kilometers wide.
"Material from the impact would have spread worldwide," he is quoted as saying. The crater is long gone, the victim of geological activity such as volcanoes and tectonic shift.
The beads were found in a 3.46 billion-year-old layer of sediment in Western Australia's Marble Bar, which once formed the sea floor.
The layer, which is able to be accurately dated as it is sandwiched between two layers of volcanic rock, is some of the oldest sediment on Earth.
Further testing found the presence of elements such as platinum, nickel and chromium in the same quantities as those found in asteroids.
Glikson says that the discovery raises hopes for further finds from Earth's ancient, violent past.
"This is just the tip of the iceberg. We've only found evidence for 17 impacts older than 2.5 billion years, but there could have been hundreds."
"Asteroid strikes this big result in major tectonic shifts and extensive magma flows. They could have significantly affected the way the Earth evolved."
The findings were published in the journal "Precambrian Research