A small plane whizzing too close for comfort by the U.S. Capitol triggered evacuations on Saturday, but the too-close aircraft wasn't the most dangerous threat in the sky over the weekend.

Coming an estimated 777,000 miles by Earth, a potentially catastrophic asteroid passed by our planet from outer space on Sunday, The Washington Post reported.  While the asteroid would have been devastating, experts said at the time that it wouldn't come nearly close enough to do any damage.

"There is zero chance of an impact," said Don Yeomans, manager of NASA's Near-Earth Object Program Office at the lab, as quoted by the Post.

Said to be about 800 feet across, the space rock would "be catastrophic if it hit the Earth," said asteroid impact expert Mark Boslough of Sandia National Laboratories in New Mexico, as quoted on Space.com. 

Scientists didn't realize the asteroid, which is nicknamed "the Beast," was coming so close until April, according to National Geographic.

"What's disconcerting is that a rocky/metallic body this large, and coming so very close, should have only first been discovered this soon before its nearest approach. HQ124 is at least 10 times bigger, and possibly 20 times, than the asteroid that injured a thousand people last year in Chelyabinsk, Siberia," said Bob Berman, an astronomer with Internet astronomy outreach venture Slooh, as quoted by National Geographic.

"If it were to impact us, the energy released would be measured not in kilotons like the atomic bombs that ended World War II, but in H-bomb type megatons."

The small plane that did come close on Saturday was a Mooney M20C, flying from Massachusetts to North Carolina. Authorities couldn't reach the aircraft's pilot before deciding to evacuate the nearby buildings, but a security official later said the close flyby was due to the pilot's confusion and not a threat. 

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