One thing is for certain: If a big enough asteroid crashes into our planet, everyone on Earth will die. We all know what happened to the dinosaurs, after all.

But what would happen to life on Earth if a similar asteroid hit the moon instead?

The short answer? “Mostly nothing,” says Reddit user 4THOT (if the asteroid is the same size as the one that killed the dinosaurs, that is) in a thread on the topic posted in the Explain Like I’m Five community. If the asteroid is much larger … well, then we might have some issues.

Take a look at this asteroid colliding into our moon in 2006:



NASA

It’s hard to see, but that faint flash in the upper right-hand corner is the site of impact. This asteroid was a mere 10 inches wide, but its collision with the moon created an intense 45-feet-wide crater. If a similar asteroid crashed into Earth, it would burn up in our atmosphere and nothing would happen.

The infamous asteroid that led to the demise of the dinosaurs was a lot bigger. Its size? Around 6 miles wide.

If an asteroid that size hits the moon, “it will just get another crater” astronomer Gareth Wynn-Williams told Popsci.

While this sounds underwhelming, it would be a spectacular view in the sky, astronomer Clark R. Chapman shared with Upvoted.

“And over the next years, centuries, and millennia, some rocks from the lunar explosion would certainly find their way to Earth as lunar meteorites. … There’s only one chance in a billion that such an impact would happen on the moon this year,” Chapman said.

In order to cause doomsday on Earth, the asteroid would have to be bigger than the moon itself.

Luckily for us, the largest-known asteroid in our solar system—Ceres—is only about 1/4 the size of the moon. If Ceres barreled towards our dear moon, it would hardly make a dent, according to Wynn-Williams.

Ceres (NASA)

That’s because our moon’s orbital momentum is so incredibly strong, it would just continue to orbit Earth, like a boss.

Even an asteroid the same size as the moon wouldn’t knock the satellite out of its orbit, though it “would certainly destroy the appearance of the moon as we know it,” Chapman said.

For the moon’s orbit to be affected, an asteroid would need to be much larger and traveling at greater speeds than our lunar satellite. If that did happen, our poor moon would shatter into pieces, says Chapman. And chunks of it would fall directly towards Earth.

“It is like asking how far you can hit a raw egg with a baseball bat. It won’t go very far at all… it will be smashed instead,” he said.

Interestingly, if it was possible for the moon to be pushed off course—even slightly—this would have disastrous effects, according to Wynn-Williams. The oceans would produce waves eight times larger than normal, submerging New York City. Fun!