School Bus-Size Asteroid to Safely Zoom Past Earth

Roughly 15 to 30 feet wide, the object will make its closest approach on Sept. 24.

A small near-Earth asteroid (or NEA) will briefly visit Earth’s
neighborhood on Thursday, Sept. 24, zooming past at a distance of about 13,000
miles (22,000 kilometers) above our planet’s surface. The asteroid will make its
close approach below the ring of geostationary satellites orbiting about 22,000
miles (36,000 kilometers) away from Earth.

Based on its brightness, scientists estimate that 2020 SW is
roughly 15 to 30 feet (5 to 10 meters) wide – or about the size of a small
school bus. Although it’s not on an impact trajectory with Earth, if it were,
the space rock would almost certainly break up high in the atmosphere, becoming
a bright meteor known as a

“There are a large number of tiny asteroids like this
one, and several of them approach our planet as close as this several times
every year,” said Paul Chodas, director of the Center for Near-Earth
Object Studies (CNEOS) at NASA’s Jet Propulsion Laboratory in Southern
California. “In fact, asteroids of this size impact our atmosphere at an
average rate of about once every year or two.”

After asteroid 2020 SW was discovered on Sept. 18 by the
NASA-funded Catalina Sky Survey in Arizona, follow-up observations confirmed
its orbital trajectory with high precision, ruling out any chance of impact.
CNEOS scientists determined that it will make its closest approach at 4:12
a.m. PDT (7:12 a.m. EDT) on Sept. 24 over the Southeastern Pacific Ocean. After
Thursday’s close approach, the asteroid will continue its journey around the
Sun, not returning to Earth’s vicinity until 2041, when it will make a much
more distant flyby.

This animation from NASA’s Center for Near-Earth Object Studies depicts asteroid 2020 SW’s trajectory as it safely passes Earth on Sept. 24, 2020. Also shown is the location of a typical geosynchronous satellite (labeled “GEOSAT”), orbiting 22,000 miles (36,000 kilometers) above Earth’s equator. Image credit: NASA/JPL-Caltech

› Larger view

In 2005, Congress assigned NASA the goal of finding 90% of
the near-Earth asteroids that are about 460 feet (140 meters) or larger in
size. These larger asteroids pose a much greater threat if they were to impact,
and they can be detected much farther away from Earth, because they’re simply much
brighter than the small ones. It is thought that there are over 100 million small asteroids
like 2020 SW, but they are hard
to discover unless they get very close to Earth.

“The detection capabilities of NASA’s asteroid surveys are
continually improving, and we should now expect to find asteroids of this size
a couple days before they come near our planet,” added Chodas.

A division of Caltech in Pasadena, JPL hosts CNEOS for
NASA’s Near-Earth Object Observations Program in NASA’s Planetary Defense
Coordination Office. More information about CNEOS, asteroids, and near-Earth
objects can be found at:

For more information about NASA’s Planetary Defense
Coordination Office, visit:

For asteroid and comet news and updates, follow
@AsteroidWatch on Twitter:

News Media Contact

Ian J. O’Neill

Jet Propulsion Laboratory, Pasadena, Calif.


Josh Handal

NASA Headquarters, Washington



Source: Jet Propulsion Laboratory

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