Five years ago, the 10,000-ton, 56-foot Chelyabinsk meteor exploded over Russia with the force of 30 atomic bombs. Yesterday, an asteroid three to six times larger than that rock came out of nowhere and passed by the Earth at a distance of 119,500 miles, about half the distance to the moon—and scientists only had a few hours’ warning before it closed in.

The asteroid, dubbed 2018 GE3, passed by Earth at 2:41 EDT Sunday morning and was estimated to be between 157 to 361 feet in diameter. In a word, it was big. It was also incredibly fast—it was traveling at a speed of 66,174 miles per hour, or Mach 86.

The most disturbing thing about 2018 GE3 is that it wasn’t spotted until it was very close to Earth, giving scientist little time to prepare or assess what the damage might be if the asteroid entered the atmosphere.

Despite an international effort to track and identify near-Earth objects—NASA’s Global Asteroid Defense System, NASA’s very real plan to blow up asteroids and meteoroids threatening Earth with nuclear weapons—2018 GE3 slipped through the net. Next time, we might not be so lucky.

Even though the Chelyabinsk meteor was smaller than this particular space rock, it still injured over a thousand people from its airburst alone and showered the Russian landscape with debris, including a half-ton chunk recovered from a lake.

Though no one has ever been killed by a falling meteorite (mostly due to their tendency to burn up in the atmosphere), the recent Tiangong-1 falling Chinese space satellite incident has proven that every sizable piece of debris that makes it through the atmosphere is another roll of the dice. Space agencies like NASA may not even be able to stop asteroids they’ve been tracking for years, when it comes down to it—the giant asteroid Bennu, for example, has a very small chance of having a cataclysmic collision with Earth—but the plans NASA has put together to deflect it may not be enough.

On top of that, we may have to deal with end times predictions: Conspiracy theorists are sounding the alarm that the Biblical prophecy says the apocalypse is coming next week, with the rise of “Planet X,” a.k.a. Nibiru, the “doomsday planet.”

Planet-killing asteroids? Planet-killing planets? Maybe it really is time to build that colony on Mars. We are counting on Elon Musk.