Largest asteroid to pass by Earth on March 21: Know all about it

2001 FO32, the interplanetary interloper which will zip past Earth at a distance of 2 million km, will provide astronomers a rare opportunity to study its size and composition

A view from inside the dome of NASA’s Infrared Telescope Facility at Hawaii’s which is being used to observe the approaching asteroid 2001 FO32. Photo: NASA

2001 FO32, the largest asteroid predicted to pass by Earth will be at its closest on March 21.

The interplanetary interloper which will zip past our planet at a distance of 2 million km with no threat of collision, will provide astronomers a rare opportunity to study the rock which according to NASA may be as ancient as the Milky Way.

Here is all you need to know about the asteroid:

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  • Scientists have been studying the orbital path of 2001 FO32 around the Sun since its discovery in 2001 and have tracked it since, Paul Chodas, director of the Center for Near Earth Object Studies, an arm of NASA’s Jet Propulsion Laboratory in Southern California has said.
  • 2001 FO32 was discovered in March 2001 by the Lincoln Near-Earth Asteroid Research (LINEAR) program in Socorro, New Mexico.
  • On basis of optical measurements, it is estimated to be 3,000 feet wide. Recent observations by NEOWISE peg its diameter at 1 km, while an analysis by the NEOWISE team say it must be 1,300 to 2,230 feet wide.
  • The asteroid is classified under the Apollo asteroid group by NASA.
  • The asteroid poses no fear of collision on earth’s surface now or for centuries to come as it will pass at a distance of 1.25 million miles (2 million km), which is 5 ¼ times the distance from Earth to Moon. However, the asteroid has been named “potentially hazardous” as the same distance is close in astronomical terms.
  • The asteroid will pass at a speech of 124,000 kmph, faster than the usual speed at which other asteroids pass by earth. The faster speed and proximity of 2001 FO32 to earth is being attributed to its highly eccentric orbit around the Sun which is inclined 39 Degrees to Earth’s orbital plane, bringing it closer to Sun than Mercury and twice as far from the Sun and Mars.
  • 2001 FO32 will pick up pace when it makes it to the inner solar system journey. NASA has described the speed akin to a “skateboarder rolling down a halfpipe”. It will slow down after it is flung back out into deep space and then swing back to the Sun. It completes one orbit every 810 days (or 2 ¼ years).
  • The asteroid will visit Earth next after 31 years, in 2052, when it will pass by the planet keeping a distance of 1.75 million miles (2.8 million km) or seven lunar distances.
  • The visit of 2001 FO32 will help astronomers understand its size and albedo (or how bright, or reflective its surface is) and give them an idea on its composition.
  • The asteroid will be observed by scientists with the help of NASA’s Infrared Telescope Facility (IRTF), a 3.2 m telescope atop Hawaii’s Mauna Kea. The telescope will observe the rock in the days leading up to its voyage by earth using its workhorse infrared spectrograph SpeX.

    When an asteroid comes in contact with sunlight, minerals on its surface absorb some wavelengths while reflecting others. Astronomers can measure the chemical “fingerprints” of these minerals by studying the light reflecting off the surface. The IRTF is being used for the same purpose. Once scientist have the data, they can make comparisons with meteorites on Earth to find out the composition of 2001 FO32.

  • The last asteroid that came close to Earth was 1998 OR2 on April 2020. While 2021 FO32 is smaller than 1998 OR2, it will be three times closer to Earth.
  • 2021 FO32 can only be watched by observers using telescopes with a diameter of 8’’ or more. While it may not visible to the naked eye, according to Earthsky those using telescopes may be able to spot it as it passes through the southern constellations of Scorpius and Sagittarius.
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