A rare double asteroid of 'mass equal' discovered in orbit around the other, says NASA-Technology News, Firstpost

An asteroid discovered last year is actually made up of two objects, each of about 900 meters and orbiting each other, revealed new sightings by three of the largest radio telescopes in the world

provided by the Morocco Oukaimeden Sky Survey in December 2017, but no detail on the physical properties of the asteroid was known up to the end of June, NASA in a statement

. only the fourth asteroid close to the Earth "equal mass" never detected, consisting of two objects of almost identical size, orbit each other.

The new observations provide the most detailed images ever obtained of this type of binary asteroid, according to the June 21, 2017 asteroid YE5 made its closest approach to Earth for at least the Next 170 years, reaching six million kilometers from the Earth, about 16 times the distance between the Earth and the Moon

June 21 and 22, observations of NASA's Goldstone Solar System Radar (GSSR) in California showed the first signs that 2017 YE5 could be a binary system.

The observations revealed two distinct lobes, but the orientation of the asteroid was such that scientists could not see if the two bodies were separated or joined

Finally, the two objects were turning to expose a separate space between them. 19659002] Scientists at the Arecibo Observatory in Puerto Rico teamed up with researchers from the Green Bank Observatory (GBO) in West Virginia to confirm that 2017 YE5 is made up of two separate objects.

New observations obtained between June 21 and June 26 indicate that the two objects rotate around each other every 20 to 24 hours

The radar imaging shows that the two objects are larger than their initial suggested optical brightness, indicating that the two rocks do not reflect as much sunlight as a typical rocky asteroid. Goldstone's images taken on June 21 also show a striking difference in the radar reflectivity of the two objects, a phenomenon that had not been observed before among more than 50 other binary asteroid systems studied.

The reflectivity differences also appear in the Arecibo images and suggest that the two objects may have different densities, compositions close to their surfaces, or different surface roughness

. over 200 meters, about 15 percent are binaries with a larger object and a much smaller satellite. Equal mass binaries like 2017 YE5 are much rarer.