An Asteroid is a small, rocky object (few centimeters to 100s of kilometers in size) that orbits the Sun. Most of the asteroids in the Solar System inhabit the region between Mars and Jupiter (forming the so-called Asteroid Belt), and are suspected to be remnants of a planet that could never form, due to the gravitational pull of the giant Jupiter. Although most of the asteroids are solitary, however, some have moons (binary asteroids). Now for the first time ever, scientists have observed a triple system, an asteroid with two moons:).

Sylvia: Artist's impression (Courtesy: ESO)Described in a report published today in the journal Nature, The asteroid is a 280-kilometer-wide body called 87 Sylvia, and lies in the asteroid belt. The moons have been named Romulus and Remus, after the children of the mythological Rhea Silvia:):). Romulus, the first moon, was discovered on February 18, 2001 using the Keck II telescope by Michael E. Brown and Jean-Luc Margot. Remus, the second moon, was discovered on images taken starting on August 9, 2004 and announced on August 10, 2005. It was discovered by Franck Marchis of the UC Berkeley and his colleagues, using Yepun, one of the telescopes in the European Southern Observatory's Very Large Telescope array.
Remus, measures seven kilometers across and travels around 87 Slyvia once every 33 hours in an orbit about 710 kilometers from the asteroid. Detailed observations of the paths of the moons around Sylvia allowed the team to calculate its mass and density, which is only 20% higher than that of water, and is mostly empty space:)). This suggests that Sylvia is a so-called rubble-pile asteroid, a patchwork of fragments created from a collision that later joined together. The small moons are most likely debris from the same collision that were later captured by the bigger body's gravitational pull:):).