This oblong asteroid will have a close encounter with Earth in 2040

NASA's Jet Propulsion Laboratory (JPL) in Southern California closely tracked one of the most elongated asteroids ever imaged by planetary radar as it flew within 1.1 million miles (1.8 million kilometers) of Earth on February 3.

The asteroid, called 2011 AG5, is more than three times as long as it's wide. This month's observations allowed NASA to learn a great deal of new information about the space rock, which will have a close encounter with Earth in 2040.

2011 AG5 asteroid is "one of the most elongated we've seen"

The Earth was never at risk of an impact from 2011 AG5, but NASA's JPL made valuable observations as it flew by earlier this month. Thanks to these observations, scientists at NASA were able to determine the asteroid's size, rotation, shape, and also a number of surface details.

2011 AG5, as its name suggests, was first discovered in 2011. Now, the new observations revealed an object roughly 1,600 feet (500 meters) long and about 500 feet (150 meters) wide, meaning it is roughly the same size as the Empire State Building. They also showed that the asteroid is dark as charcoal and that it has a slow rotation rate, as it takes roughly nine hours to fully rotate.

The observations were made using the 230-foot (70 meters) Goldstone Solar System Radar antenna dish at the Deep Space Network's facility near Barstow, California.

"Of the 1,040 near-Earth objects observed by planetary radar to date, this is one of the most elongated we've seen," Lance Benner, principal scientist at JPL who led the observations, explained in a NASA blog post.

New observations allow scientists to measure the asteroid's orbit

Crucially, the new observations allowed for more precise measurements of the asteroid's orbit around the Sun. The radar observations helped scientists at NASA's Center for Near Earth Object Studies (CNEOS) refine the asteroid's predicted orbital path, allowing them to better determine whether it could ever be a threat to Earth.

Asteroid 2011 AG5 orbits the Sun once every 621 days. In 2040, it will have a close encounter with Earth, but it will ultimately fly safely past our planet at a distance of about 670,000 miles (1.1 million kilometers).

"Interestingly, shortly after its discovery, 2011 AG5 became a poster-child asteroid when our analysis showed it had a small chance of a future impact," Paul Chodas, the director for CNEOS at JPL, explained in a NASA blog post. "Continued observations of this object ruled out any chance of impact, and these new ranging measurements by the planetary radar team will further refine exactly where it will be far into the future."