NASA was able to image an asteroid larger than the Empire State Building and of similar proportions as it hurtled past Earth in early February 2023.
The asteroiddesignated 2011 AG5, passed safely past our planet at a distance of about 1.1 million miles (1.8 million kilometers), about five times the distance between Earth and moon. But even if it posed no danger of impacting our planet, the asteroid could actually still have a major scientific impact.
The close approach allowed scientists at NASA’s Jet Propulsion Laboratory (JPL) in Southern California to track the space rock and make invaluable observations to determine its size, rotation, surface details and, especially, its shape.
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This possibility, the first to allow astronomers to take such a close look at 2011 AG5 since its discovery in 2011, revealed the asteroid to be about 1,600 feet (500 meters) long and about 500 feet (150 m) wide. This means that the asteroid is extremely elongated.
At just over three times as long as it is wide, the asteroid has surprisingly similar proportions to the Empire State Building, one of the New York skyline’s most striking sights.
“Of the 1,040 near-Earth objects observed by planetary radar to date, this is one of the most elongated we’ve seen,” JPL principal investigator Lance Benner, who led the observations, said in a statement. (opens in a new tab)
The observations were collected with 230 ft (70 m) Goldstone Solar System Radar antenna dish at the Deep Space Network’s facility near Barstow, California, between January 29 and February 4 this year.
The telescope caught several other distinguishing features of 2011 AG5, including a concave dent in one of the asteroid’s two hemispheres. The asteroid also has subtle dark and light areas that may indicate small surface features only a few meters in diameter. Despite these variations in shade, the asteroid would appear pitch black if viewed with the human eye.
The research team was also able to determine that 2011 AG5 rotates slowly, taking around 9 hours to complete one full turn.
The Goldstone observations also give astronomers at JPL’s Center for Near Earth Object Studies (CNEOs) a better idea of the orbit of the space rocks, which take 621 Earth days to orbit the Sun.
Asteroid 2011 AG5 was the focus of much attention shortly after its discovery, when it was suspected to have a small chance of impacting Earth in 2040.
“Interestingly, shortly after its discovery, 2011 AG5 became a poster child asteroid as our analysis showed it had little chance of a future impact,” Director of CNEOS at JPL Paul Chodas said in the statement. “Continued observations of this object ruled out any chance of an impact, and these new distance measurements from the planetary radar team will further delineate exactly where it will be far into the future.”
While 2011 AG5 will not hit Earth in 2040, the asteroid will be back for another close approach, where it will come even closer, passing our planet at a distance of about 670,000 miles (1.1 million kilometers), about three times Earth’s distance. Moon distance
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