NASA Scientist Responds: When was the last time an asteroid hit Earth?

About 26,115 asteroids have skimmed the Earth since 1990, according to NASA’s Center for Near-Earth Object Studies.

Of these, 888 had a diameter of more than one km., Which made them two and a half times taller than the Empire State Building in New York.

But when was the last time an asteroid hit Earth?

According to Marina Brozovic, a scientist at NASA’s Jet Propulsion Laboratory, the answer depends on your definition of being hit by an asteroid.

Smaller asteroids hit Earth almost all the time, Brozovic told NASA’s “We Asked a NASA Scientist” program. However, due to the smaller scale of those asteroids, they burn up in the atmosphere, rendering their impact null and void.

NASA has labeled any asteroid 140 meters or more that comes close to the planet as a potentially dangerous asteroid (PHA), because it has the potential to cause catastrophic damage to Earth.

Illustrative asteroid (credit: Wikimedia Commons)

During the last century, the most important asteroid to hit Earth was one the size of a small building that flew over Russia in 2013. That asteroid disintegrated only 20 km. above the ground, causing a large number of meteorites to scatter over the Russian city of Chelyabinsk.

But when was the last asteroid to make a major impact on Earth, leaving craters in its wake and causing massive amounts of devastation?

“We have to go back in time for such an event,” Brozovic replied. “Those old craters are not easy to spot.”

“For now, they are full of sediment or they may be at the bottom of the ocean,” Brozovic said.

During Earth’s early years, the planet was furiously bombarded by massive ancient asteroids, 10 times more often than previously believed, and may have delayed the planet’s ability to host life.

However, even today, asteroids can pass through Earth without anyone noticing.

In October, an asteroid skimmed the Earth just 3,000 kilometers from the planet’s surface, but no one realized it until after the fact.

Aaron Reich contributed to this report.

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