An asteroid the size of a skyscraper made a “relatively close” approach to Earth on Tuesday.

According to NASA’s Jet Propulsion Laboratory website, the “potentially hazardous” space object—called 2021 KT1—is believed to be about 600 feet in diameter, which would make it bigger than the Washington Monument and about the size of the Seattle Space Needle. NASA states the asteroid is traveling at a speed of 400,000 miles per hour and flew within 4.5 million miles of Earth. For comparison, that’s about 19 times the distance between our planet and the moon. 

Although its distance didn’t seem “close,” 2021 KT1 was still considered a “potentially hazardous object”—a classification given to asteroids that are either larger than 490 feet in diameter or come within 4.6 million miles of Earth. Any asteroids smaller or further are not considered “potentially hazardous.”

“No one should be overly concerned about an Earth impact of an asteroid or comet. The threat to any one person from auto accidents, disease, other natural disasters and a variety of other problems is much higher than the threat from [near Earth objects],” NASA’s Center for Near-Earth Object Studies states. “Over long periods of time, however, the chances of the Earth being impacted are not negligible so that some form of NEO insurance is warranted. At the moment, our best insurance rests with the NEO scientists and their efforts to first find these objects and then track their motions into the future. We need to first find them, then keep an eye on them.”

According to the JPL website, 2021 KT1 is one of three asteroids that zoomed near our planet Tuesday. There’s 2021 KT2, a bus-size asteroid that flew within 181,000 miles of Earth; as well as 2018 LB, an airplane-size (70 feet) asteroid that came within 694,000 miles. Two house-sized asteroids, 2021 JW6 and 2021 KE1, will pass Earth Wednesday, and flying within 1,930,000 and 3,580,000 miles, respectively.