Massive Asteroid Flew By Earth Before Scientists Even Saw It

Some days, scientists find asteroids months before they're expected to pass by our planet. Other days, those same crews may not notice a warehouse-sized asteroid zoomed by Earth until...well, it already zoomed by. That's the case recently with an asteroid officials are now calling 2021 SG, a space-faring rock that passed by the planet on September 16th — only scientists weren't able to see it because it came from the direction of the sun. 

According to data released by the NASA-backed Minor Planet Center, 2021 SG has a diameter of anywhere between 42 meters and 94 meters. For non-scientists, that's roughly 138 feet to 308 feet. In comparison, it's about the size of Cinderella's Castle at Walt Disney World so, yeah, a hefty chunk of rock.

EarthSky suggests the asteroid passed by the planet at a distance comparable to half the distance from this planet to the moon. NASA considers anything passing by the planet within 121 million miles a "Near-Earth Object," meaning 2021 SG most certainly meets the qualifications. A similar asteroid broke up over Chelyabinsk, Russia in 2013 and sent shockwaves through six cities in the area. Around 1,500 Russians had to seek medical attention after the event, largely as a result of broken glass and flying debris.

If 2021 SG managed to enter Earth's atmosphere, EarthSky says the situation could have been much more dangerous considering the asteroid was barreling through space at an "amazing speed" of 53, 281 miles per hour.

The incident in Russia was caused by another asteroid that came from the direction of the sun, a long-standing issue for scientists in the NEO field. Luckily for them, NASASA is actively working on launching the NEO Surveyor, a new telescope that will be stationed between the fiery star and Earth, hunting down asteroids that meet these exact specifications.

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"By searching for NEOs closer to the direction of the Sun, NEO Surveyor would help astronomers discover impact hazards that could approach Earth from the daytime sky," said Amy Mainzer, principal investigator for NEO Surveyor at the University of Arizona. "NEO Surveyor would also significantly enhance NASA's ability to determine the specific sizes and characteristics of newly discovered NEOs by using infrared light, complementing ongoing observations being conducted by ground-based observatories and radar."

Cover photo by Tobias Roetsch/Future Publishing via Getty Images