Washington, Feb 14 : Astronomers have discovered the first near-Earth triple asteroid, which is hardly 7 million miles from our planet.
Known as 2001 SN263, the asteroid, with three bodies orbiting each other, was discovered by astronomer Michael C. Nolan and his colleagues using the sensitive radar telescope at Cornell University's Arecibo Observatory in Puerto Rico.
The main, central body is spherical with a diameter of roughly 1.5 miles (2 kilometers), while the larger of the two moons is about half that size. The smallest object is about 1,000 feet across, or about the size of the Arecibo telescope.
Other triple asteroids exist in the asteroid belt (between Mars and Jupiter) and beyond, but this is the first near-Earth system where the actual shapes of objects can be clearly seen.
"This discovery has extremely important implications for ideas about the origins of near-Earth asteroids and the processes responsible for their physical properties," said Nolan.
"Double, or binary, asteroid systems are known to be fairly common - about one in six near-Earth asteroids is a binary - but this is the first near-Earth triple system to be discovered," he added.
The orbits of binary - and now triple - asteroid systems unveil the mass and allow astronomers to assess whether they are stable over millennia or have formed very recently.
According to Nolan, because of the small sizes and irregularly shaped components, 2001 SN263 should offer unique insights relative to the much larger triple systems in the main asteroid belt.
"Examining the orbits of the moons as we continue to observe 2001 SN263 over the next few weeks may allow us to determine the density of the asteroid and type of material from which it is made," said Nolan.
"We will also be studying its shape, surface features and regolith (blanketing material) properties," he added.