2 asteroids safely buzzed close by Earth this week

Two asteroids made close flybys of Earth on Monday (Sept. 14), in both cases showing a common occurrence that didn't put our home planet at any risk.

The first space rock, a bus-size asteroid called 2020 RF3, whizzed by our planet 58,500 miles (94,000 kilometers) away at 2:49 a.m. EDT (0649 GMT), according to the NASA Jet Propulsion Laboratory's Center for Near Earth Object Studies. That's the equivalent distance of one-quarter of the way to Earth's moon, a distance of 239,000 miles (385,000 km).

A few hours later, a smaller, car-size asteroid 2020 RD4 made a similar close pass at 65,700 miles (roughly 106,000 km), at 4:33 p.m. EDT (2033 GMT), the center added (opens in new tab). Italy's Virtual Telescope Project also hosted a livestream for the 2020 RD4 event (opens in new tab)

Video: Bus and car-size asteroids zip by Earth on same day
Potentially dangerous asteroids (images)

Asteroids make close passes to Earth many times a year, since there are many thousands of them in our solar system. NASA and a network of telescopes keep a close eye for any dangerous space rocks through entities such as the NASA's Planetary Defense Coordination Office. Fortunately, no immediate threats to Earth have been found.

There are some recorded instances of asteroids causing damage during Earth's history, which is why space experts keep an eye on the skies. A recent well-known incident saw a six-story object breaking up over Chelyabinsk, Russia in 2013, which caused building damage and some injuries. More famously, the dinosaurs' extinction 66 million years ago is usually attributed to a much larger object that slammed into our planet.

Aside from watching for threatening objects, astrophysicists study asteroids to learn more about how the early solar system was formed. Asteroids and icier objects known as comets are leftover pieces of our cosmic neighborhood before most of the material coalesced into the planets and moons we see today.

These orbit diagrams show the close approaches of asteroids 2020 RF3 and 2020 RD4 on Sept. 14, 2020. (Image credit: NASA JPL)

Scientists do regular study of asteroids with telescopes and, where possible, use spacecraft data to supplement their understanding. Two spacecraft are readying to bring samples of asteroids back to Earth soon, which is a rare occurrence indeed. 

NASA's OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer) is scheduled to swoop down to asteroid Bennu on Oct. 20 and bring the sample back to Earth in September 2023. Meanwhile, the Japanese Aerospace Exploration Agency has a mission of its own, Hayabusa2, that is en route from asteroid Ryugu for a landing on Earth on Dec. 6.

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Elizabeth Howell
Staff Writer, Spaceflight

Elizabeth Howell, Ph.D., is a staff writer in the spaceflight channel since 2022. She was contributing writer for Space.com (opens in new tab) for 10 years before that, since 2012. Elizabeth's reporting includes an exclusive with Office of the Vice-President of the United States, speaking several times with the International Space Station, witnessing five human spaceflight launches on two continents, working inside a spacesuit, and participating in a simulated Mars mission. Her latest book, "Why Am I Taller?", is co-written with astronaut Dave Williams. Elizabeth holds a Ph.D. and M.Sc. in Space Studies from the University of North Dakota, a Bachelor of Journalism from Canada's Carleton University and (soon) a Bachelor of History from Athabasca University. Elizabeth is also a post-secondary instructor in communications and science since 2015. Elizabeth first got interested in space after watching the movie Apollo 13 in 1996, and still wants to be an astronaut someday. Mastodon: https://qoto.org/@howellspace

  • Catastrophe
    "Size of a bus" according to Wiki is about a ton, give or take.

    This is about the size of Chelyabinsk - the damage potential, again according to Wiki, is:

    "The explosion generated a bright flash, producing a hot cloud of dust and gas that penetrated to 26.2 km (16.3 mi), and many surviving small fragmentary meteorites, as well as a large shock wave. The bulk of the object's energy was absorbed by the atmosphere, with a total kinetic energy before atmospheric impact estimated from infrasound and seismic measurements to be equivalent to the blast yield of 400–500 kilotons of TNT (about 1.4–1.8 PJ) range – 26 to 33 times as much energy as that released from the atomic bomb detonated at Hiroshima."
    And that about one third the distance of the Moon away.
    And there was another with it (thankfully smaller).

    About 30 times Hiroshima. Could have made a little mess! Depends where it hit.

    I am not scared, but I am a little apprehensive.

    Cat :)