• Asteroids 2016 CZ31 and 2013 CU83 will swing past Earth on July 29 and July 30, respectively.
  • As large as 1,000 feet across, the asteroids won’t get closer than 1.7 million miles from Earth.
  • Less than a decade ago, an asteroid 65 feet in size exploded in Earth’s sky, emitting a damaging shockwave.

When an asteroid about 65 feet in diameter exploded about 18 miles from Earth’s surface above Russia in 2013, the shockwave spanned six cities, injuring 1,500 and damaging more than 7,000 buildings. Fortunately, the two massive asteroids passing Earth this week have no chance of coming close enough to elicit fear or cause harm. The 1.7-million-mile buffer between Earth and asteroid 2016 CZ31 ensures that we'll be safe.

As tracked by NASA’s Center for Near Earth Object Studies (CNEOS), two abnormally large asteroids will present what experts deem a close encounter with Earth, even though the fly-bys happen at quite a safe distance. The first, at 7:02 p.m. Eastern Time on Friday, July 29, will send asteroid 2016 CZ31 screaming past Earth 1.7 million miles away at a speed of 34,5000 miles per hour. As Newsweek reports, this is 17 times faster than a rifle bullet and one-fifth as fast as a bolt of lightning.

The zooming rock isn’t as large as the one coming the next day, but at up to 722 feet across—taller than Seattle’s Space Needle—it sure dwarfs the 2013 asteroid event.

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The magnitude of the distance, as much as seven times as far away from Earth as the Moon is, doesn’t cause alarm, but still qualifies as a near Earth object in the grand scope of the Milky Way.

Almost exactly 24 hours after the 2016 CZ31 event, at 7:37 p.m. ET on Saturday, July 30, the much larger 2013 CU83 asteroid, this one as big as 1,050 feet across, will swing by Earth at a relatively pedestrian 13,100 miles per hour, at over 3 million miles away. It’s similar in height to both the Eiffel Tower in Paris and the Empire State Building in New York City.

The NASA center monitors space objects continually, with near Earth encounters happening regularly, but most of the 29,000 asteroids are too small to pose any risk. The most recent asteroid to enter Earth’s atmosphere, 2022 EB5, measured just over 6 feet in width and disintegrated upon entering the atmosphere over the Norwegian Sea on March 11, 2022.

NASA’s Scout impact hazard assessment system predicted the collision based on calculated trajectory, just the fifth small asteroid to be detected in space before hitting Earth's atmosphere. As the survey system becomes more sophisticated and sensitive, researchers expect more objects will be detected before entering the atmosphere. And the larger the asteroid, the greater the opportunities to discover and track trajectories, often giving multiple years' notice of any potential impact.

“Tiny asteroids like 2022 EB5 are numerous, and they impact into the atmosphere quite frequently, roughly every 10 months or so,” Paul Chodas, director of CNEOS, says in a news release. “But very few of these asteroids have actually been detected in space and observed extensively prior to impact, basically because they are very faint until the last few hours, and a survey telescope has to observe just the right spot of sky at the right time for one to be detected.”

Researchers have known about the two massive asteroids moving past us this week for years, and their sheer distance from Earth means we can marvel as their size, speed, and relative closeness while taking solace in the fact that–in the scope of outer space distances—these near Earth objects are only relatively close to Earth.