Astronomers stunned by rare DOUBLE asteroid — NASA asteroid WARNING

James Marshall
July 16, 2018

The bouncing-baby asteroids were revealed by three radar telescopes, which shoot a beam of radio waves at nearby asteroids and wait for the reflection to return to Earth. Each little world is about 3,000 feet (900 meters) in size.

The reflectivity differences also appear in the Arecibo images and hint that the two objects may have different densities, compositions near their surfaces, or different surface roughnesses.

The binary system consists of a pair of asteroids of almost identical mass at around 3,000 feet in size.

"The discovery of the binary nature of 2017 YE5 provides scientists with an important opportunity to improve understanding of different types of binaries and to study the formation mechanisms between binaries and contact binaries, which may be related".

Several months later, 2017 YE5 brushed close to Earth, making its closest approach in the next 170 years.

Astronomers with the Morocco Oukaimeden Sky Survey (MOSS) discovered the near-Earth asteroid 2017 YE5 on December 21, 2017. But the object (s) didn't come closest to us until June 21, 2018. The new observations took advantage of asteroid's closest approach to Earth, when it flew by about 3.7 million miles (6 million kilometers) away.

The scientists estimate the asteroids measure about 3,000 feet in size each. This is quite rare and only the fourth "equal mass" binary system that's ever been recorded.

Three of the world's largest radio telescopes team up to show a rare double asteroid.

Bi-static radar images of the binary asteroid 2017 YE5 from the Arecibo Observatory and the Green Bank Observatory on June 25. Image via Arecibo/GBO/NSF/NASA/JPL-Caltech.

NASA's astronomers at the Goldstone Sola System Radar (GSSR) in California determined YE5 was not one, but two asteroids - a so-called binary system. This may indicate that the binary asteroid was actually originally two separate objects that were drawn into a mutual orbit when in close proximity.

A few days after the Goldstone's initial observations, the Arecibo Observatory in Puerto Rico and the Green Bank Observatory in West Virginia, United States both independently confirmed it: 2017 YE5 is a binary system of two equally sized asteroids. Most of the binary systems that have been witnessed consist of two objects of wildly different sizes. "This is only the fourth "equal mass" binary near-Earth asteroid ever detected, consisting of two objects almost identical in size, orbiting each other", read NASA's statement. This was confirmed with visible-light observations of brightness variations by Brian Warner at the Center for Solar System Studies in Rancho Cucamonga, California. 2017 YE5 is likely as dark as charcoal.

In addition, each object was found to reflect the radar signal differently pointing to a potential difference in either surface compositions or roughness, or even densities.

NASA's new photographs of the binary system offer the most detailed observations yet of this unusual phenomenon.

Binary systems are actually quite common in the solar system with 15 percent of all asteroids travel with a partner. The observations, conducted on June 23, 2018, show two lobes, but do not yet show two separate objects.

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