You can watch an asteroid zoom safely by Earth in a live webcast today

A huge asteroid will safely fly by Earth today (March 3), and you can watch it live online. 

The Virtual Telescope Project is planning to stream live telescope views of the asteroid 138971 (2001 CB21) during its approach. The space rock is technically classified as "potentially hazardous", but there's no need to worry. The asteroid will pass by at the equivalent of nearly 13 times the average Earth-moon distance (3 million miles, or 4.9 million kilometers), according to the Center for Near-Earth Object Studies (CNEOS) managed by NASA's Jet Propulsion Laboratory. 

Asteroid 2001 CB21 measures between 1,800 feet (560 meters) and 0.7 miles (1.2 kilometers) in diameter, according to CNEOS. That's about as big as Chicago's Navy Pier.

The Virtual Telescope Project's event starts at 10 p.m. EST (0300 GMT Thursday, March 4). Typically the project uses a telescope based near Rome, run by founder Gianluca Masi. "The potentially hazardous asteroid (138971) 2001 CB21 will have a relatively close and obviously safe flyby with our planet," Masi said in a statement. "The Virtual Telescope Project will show it to you live, online: join us from the comfort of your home!"

Related: The greatest asteroid missions of all time!

The Virtual Telescope Project captured this view of asteroid 138971 (2001 CB21) ahead of a March 4, 2022 flyby. (Image credit: Virtual Telescope Project)

If you're looking for a telescope or binoculars to spot asteroids like this one, check out our guide for the best binoculars deals and the best telescope deals available now. Our best cameras for astrophotography and best lenses for astrophotography can also help you pick the best imaging gear.

NASA keeps its eyes peeled for asteroids using a network of partner telescopes as well as space observations, coordinated through the Planetary Defense Coordination Office. The agency has found no imminent threats yet, but it continues the search to be proactive.

The agency also tests out asteroid defense technologies (not that we need them yet) such as one that will arrive at an asteroid moon very shortly. In late September or early October 2022, the 1,210-pound (550 kilograms) DART spacecraft will slam into a small asteroid named Dimorphos, changing this space rock's orbit around its larger companion, Didymos

Overall we know of around 750,000 asteroids, but the vast majority don't come anywhere near Earth. Scientists have identified more than 27,000 near-Earth asteroids, with new ones spotted constantly. 

Potentially hazardous asteroids are classified as those space rocks over a certain brightness (implying a certain size, although the correlation isn't perfect) that come within 4.65 million miles (7.48 million km) of Earth. (The distance is one-twentieth of the average distance between Earth and the sun.)

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Elizabeth Howell
Staff Writer, Spaceflight

Elizabeth Howell (she/her), Ph.D., is a staff writer in the spaceflight channel since 2022 covering diversity, education and gaming as well. She was contributing writer for for 10 years before joining full-time. Elizabeth's reporting includes multiple exclusives with the White House and Office of the Vice-President of the United States, an exclusive conversation with aspiring space tourist (and NSYNC bassist) Lance Bass, speaking several times with the International Space Station, witnessing five human spaceflight launches on two continents, flying parabolic, 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 a Bachelor of History from Canada's Athabasca University. Elizabeth is also a post-secondary instructor in communications and science at several institutions since 2015; her experience includes developing and teaching an astronomy course at Canada's Algonquin College (with Indigenous content as well) to more than 1,000 students since 2020. Elizabeth first got interested in space after watching the movie Apollo 13 in 1996, and still wants to be an astronaut someday. Mastodon: