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An asteroid the size of the Golden Gate Bridge to make "very close encounter" with Earth this weekend

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An asteroid similar in size to the Golden Gate Bridge will whip past our planet this weekend — the largest and fastest asteroid to pass by Earth this year. 

But don't worry, it won't get too close. 

The asteroid, officially known by NASA as 231937 (2001 FO32), is smaller than the last notable one to closely approach Earth, but it will be three times closer, NASA said in a statement

2001 FO32 is about 1,300 to 2,230 feet wide, according to observations made by the NEOWISE mission team, putting it at the smaller end of the scale. It has an orbit period of 810 days. 

It will be here to mark the first full day of spring. 

2001 FO32 is quickly approaching our planet, set to come within 1.25 million miles of Earth at 11:02 a.m. ET on Sunday, March 21, just one day after the spring equinox. That's close enough for NASA to classify it as "potentially hazardous" in its database of near-Earth asteroids, a designation that is given when an asteroid comes within about 4.65 million miles of Earth, and is larger than 500 feet in diameter. 

This diagram depicts the elongated and inclined orbit of 2001 FO32 as it travels around the Sun (white ellipse). Because of this orbit, when the asteroid makes its close approach to Earth, it will be traveling at an unusually fast speed of 77,000 mph. ASA/JPL-Caltech

The asteroid will zoom past at almost 77,000 miles per hour, or 21 miles per second — peaking scientists' interests as one of the fastest space rocks known to fly past Earth. It is "unusually speedy" due to its highly inclined and elongated orbit around the sun, which takes it closer to the sun than Mercury and twice as far from the sun as Mars. 

"This is the closest predicted approach in 2021 for any moderately large asteroid, where 'moderately large' means at least several hundred meters in size," Paul Chodas, the Director of the Center for Near-Earth Object Studies, told CBS News. 

However, it poses no risk of impact, and scientists know its path very accurately, having studied it for about two decades. 

"As 2001 FO32 makes its inner solar system journey, the asteroid picks up speed like a skateboarder rolling down a halfpipe, and then slows after being flung back out into deep space and swinging back toward the Sun," NASA said. 

An artistic rendering creates an approximate landscape of 2001 FO32 with Mount Everest in the background. Shape, color and texture of the asteroid are imagined.  Space Reference

The upcoming encounter gives astronomers the unique opportunity to gain a better understanding of the asteroid, including its size, reflectiveness and composition. Some of the studies will make use of NASA's Infrared Telescope Facility (IRTF) on Hawaii's Mauna Kea. 

"We're trying to do geology with a telescope," said Vishnu Reddy, associate professor at the University of Arizona's Lunar and Planetary Laboratory in Tucson. "We're going to use the IRTF to get the infrared spectrum to see its chemical makeup. Once we know that, we can make comparisons with meteorites on Earth to find out what minerals 2001 FO32 contains."

Additionally, researchers may use radar observations by NASA's Deep Space Network, which has ground stations in California, Spain and Australia, to study the asteroid's orbit, dimensions, rotation rate, surface features and potential satellites. 

"Observations dating back 20 years revealed that about 15% of near-Earth asteroids comparable in size to 2001 FO32 have a small moon," said Lance Benner, principal scientist at JPL. "Currently little is known about this object, so the very close encounter provides an outstanding opportunity to learn a great deal about this asteroid."

This photo shows the view from inside the dome of NASA's Infrared Telescope Facility during a night of observing. The 10.5-foot telescope atop Hawaii's Mauna Kea will be used to measure the infrared spectrum of asteroid 2001 FO32.  UH/IfA

At its brightest, the space rock will still be "far too faint" to be seen with the naked eye, Chodas said. But space enthusiasts can spot it with a telescope.

"A fascinating aspect of asteroids is that observers using backyard telescopes can spot them as apparently slow-moving 'stars,'" EarthSky said. "It typically takes at least 5 to 10 minutes for backyard telescope users to detect a space rock's motion in front of its starfield. But asteroid 2001 FO32 will be sweeping past Earth at such a fast pace that, when it's closest, observers using 8-inch or larger telescopes might be able to detect its motion – its drift in front of the stars – in real-time."

Observers at lower northern latitudes and in the southern hemisphere will have the best chance to spot it at its brightest, Chodas said. Star charts will help locate it.  

Telescopes in New Mexico that are part of the Lincoln Near-Earth Asteroid Research program detected the asteroid in March 2001. The MIT Lincoln Laboratory program, funded by the U.S. Air Force and NASA, has been monitoring it since. 

After its visit on March 21, FO32 will continue its "lonely voyage" — not returning to Earth again until 2052. In that year, it will come within 1.75 million miles of Earth, or about seven lunar distances. 

The current biggest known threat is an asteroid called (410777) 2009 FD, which has less than a 0.2% chance of hitting Earth in 2185, according to NASA's PDCO

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