Radar Observations of Elongated Near-Earth Asteroid 2011 AG5

This collage represents NASA radar observations of near-Earth asteroid 2011 AG5 on Feb. 4, 2023, one day after its close approach to Earth brought it about 1.1 million miles (1.8 million kilometers, or a little under five times the distance between the Moon and Earth) from our planet. While there was no risk of 2011 AG5 impacting Earth, scientists at NASA's Jet Propulsion Laboratory in Southern California closely tracked the asteroid, making invaluable observations to help determine its size, rotation, surface details, and shape. More than three times as long as it is wide, 2011 AG5 is one of the most elongated asteroids to be observed by planetary radar to date. This close approach provided the first opportunity to take a detailed look at the asteroid since it was discovered in 2011, showing an object about 1,600 feet (500 meters) long and about 500 feet (150 meters) wide – dimensions comparable to the Empire State Building. The powerful 230-foot (70-meter) Goldstone Solar System Radar antenna dish at the Deep Space Network's facility near Barstow, California, revealed the asteroid's noteworthy dimensions. The Goldstone observations show that 2011 AG5 has a large concavity in one of its hemispheres and some subtle dark and lighter regions that may indicate small-scale surface features a few dozen meters across. If viewed by the human eye, 2011 AG5 would appear as dark as charcoal. The observations also confirmed the asteroid has a slow rotation rate, taking nine hours to fully rotate. https://photojournal.jpl.nasa.gov/catalog/PIA25259