A misterious asteroid

Bennu is a small asteroid circling around the sun in an orbit very close to the Earth orbit. As such it passes near earth on a periodic basis and there is some probability that it might hit our planet in the near future.

It is very small, not more than 1 km in largest diameter and has a very low albedo (around 5% or less) showing that its surface is composed of carbon compounds.

Bennu was discovered by the Lincoln Near-Earth Asteroid Research 

LINEAR) project, which detects and tracks near-Earth objects, in 1999. It 

has provisionally names 1999 RO36, which indicates that it was the 916th object observed in the first half of September 1999, according to the Planetary Society. After its orbit was precisely measured, the object was given an official sequential number, and because 1999 RQ36 was the 101,955th asteroid to receive a number, its official name became Asteroid 101955.

The name Bennu was selected after a "Name That Asteroid!" contest held by the University of Arizona and other partners. Michael Puzio, a third-grade student in North Carolina,suggested the name of an Egyption mythological bird. Michael said the shape of the spacecraft (including its outstretched sample arm) reminded him of the heron god, which was called Bennu. Only about 5 percent of numbered asteroids have been given names, according to the Planetary Society.

Bennu has a shape that looks a bit like a spinning top. It is roughly 500 meters (1,640 feet) in diameter and orbits the sun once every 1.2 years, or 436.604 days. Every six years or so, it comes very close to Earth — about 0.002 AU, according to the University of Arizona (An astronomical unit is the distance between the Earth and the sun. So, 0.002 AU is roughly 186,000 miles or 300,000 kilometers — well within the orbit of Earth's moon.)