* Astronomy

The 1.0 km wide,  magnitude 13,  asteroid 2008 BT18  will make a near-Earth flyby (5.9 LD, 0.015 AU) on  July 14.

Astronomers have just discovered that it is a binary system.

"The sizes of the two components are 600 m for the primary and >200 m for the secondary. The primary looks spheroidal, but we don't yet know about the shape of the secondary" - Lance Benner, JPL

Benner and others used the Arecibo radio telescope in  Puerto Rico, to obtained a "delay-doppler" image of the pair on July 7th:

"We're also getting images from NASA's Goldstone radar in the Mojave desert of California" 

Goldstone  radar is smaller than Arecibo but should reveal much about the target, including the binary orbit, masses and bulk density of the components.
About 16% of all near-Earth asteroids are binaries, but only a handful have come this close.
Southern hemisphere observers may be able to observe this double-rock using your own backyard telescope and CCD camera. At closest approach (1.4 million miles) on July 14th, 2008 BT18 will fly through Canis Major heading south and glowing like a 13th magnitude star.

Source NASA