An asteroid about the size of a bus and first spotted on Christmas Day will buzz by Earth today at a speed of 21,000 mph, according to NASA’s Jet Propulsion Laboratory.
Named 2017 YZ4, the space object will barrel by the Earth at a distance of just 139,433 miles (224,000km)— a near miss in terms of astrological measurements.
‘This is the first known asteroid to fly by Earth within one lunar distance, since two such asteroids flew past us 35 minutes apart on November 21, and the 52nd this year’, a NASA spokesperson told the Express.
For reference, the distance between the Earth and the moon is 238,855 miles (384,400 km).
The space rock measures around 22.6 to 49 feet in diameter (seven to 15 meters) and will buzz Earth at around 4.56pm GMT (11.56 ET) on Thursday, Dec. 28.
YZ4 will be known by its unaffectionate designation until given a more lively name, like that given to “Phaethon 3200,” the much reported on “mysterious” space object that flew by our planet on Dec. 16.
Phaethon 3200, named after a mythical Greek god that nearly destroyed the Earth, is technically defined as an asteroid, in fact, the first ever to be discovered by satellite. But it’s also the parent object that produced a unique meteor shower called the Geminids, something asteroids are, in theory, incapable of producing.
Other theories say that it’s a dead comet or a rock comet.
“So what it comes down to is that the Geminid parent object is a mystery,” says NASA’s Marshall Space Flight Center’s fact sheet.
But, however NASA eventually defines the space object cyclically careening through space in our general direction, Phaethon is expected to come even closer in 2093—to within 1.8 million miles.
Phaethon “measures 5 km wide, about half the size of the asteroid or comet that wiped out the dinosaurs 65 million years ago,” writes Dr. Tony Phillips, production editor of NASA Science.
That is why NASA defines Phaethon as a Potentially Hazardous Object.
For NASA to classify a space rock as “hazardous”, it must not only have the potential to make close approaches to Earth, but cause serious damage in the event of impact.
The space agency closely monitors objects that could come perilously close to Earth through its Near Earth Object Program. New PHAs are being discovered every month and still there are tens of thousands of uncharted PHAs of significant size, according to the Large Synoptic Survey Telescope (LSST) project. Best estimates are that there are 10,000 to 20,000 PHAs larger than 328 feet.
By astronomical terms, 2017 YZ4 is merely a Near-Earth Object and not a Potentially Hazardous Asteroid, according to this IAU list of PHAs.
“As of December 24, there are 17,495 known Near-Earth Objects (NEOs) around our planet; 17,389 are asteroids,’ a NASA spokesperson told the Express.
‘This year, we discovered 1,985 new near Earth asteroids. There were 1888 such objects discovered in 2016 and 1,571 in 2015.”
YZ4 was first spotted at the Mt. Lemmon Survey observatory, northeast of Tucson, Arizona, according to the International Astronomical Union’s Minor Planet Center note on the new asteroid.
The approximate speed at which 2017 YZ4 will streak past the Earth and the moon Thursday is 21,000 miles per hour (33,800 kilometers per hour).
Watch this analysis of what would happen if even a tiny meteor were to hit Earth at a velocity approaching the speed of light: