So close, yet so far away
Astronomers discover a binary system that boasts the widest separation known in the solar system
By Ron Cowen
Long-distance relationships are tough enough when partners are a continent apart. Consider the plight of two solar system bodies separated by a distance more than 20 times as great.
Astronomers have found such a partnership: two equal-mass members of the Kuiper belt, the reservoir of frozen objects beyond Neptune, that are gravitationally bound to each other but separated by more than 100,000 kilometers.
Known collectively as 2001 QW322, the frozen couple is the most widely separated binary system known in the solar system.
The system’s very existence poses a challenge because no one had predicted two bodies could survive as a pair with such a wide separation, says co-discoverer Jean-Marc Petit of the Besancon Observatory in France. Indeed, the two bodies, which each have an estimated diameter of 54 kilometers, are so weakly bound that they would be easily disrupted by the gravity of an interloper, he notes.