The Visitor and Its Moon

On May 31, 2013, Earth had a visitor. It was not a solitary one. The asteroid designated 1998 QE2, a dark, carbon-rich mass approximately 2.7 kilometers in diameter, sailed past at a distance of 5.8 million kilometers. That is fifteen times the distance to the Moon. A safe passage. The event was notable not for its threat, which was nonexistent, but for its composition. Radar observations from the Goldstone Deep Space Communications Complex revealed the asteroid was not alone. It was a binary system. A smaller body, a moon roughly 750 meters across, was in orbit around the primary. This moonlet, revealed by the precise ping of radar waves, completed a rotation every 32 hours. The pair approached, reached their perigee, and began their long recessional. Their trajectory, governed by gravity and momentum, ensures they will not come this close again for at least two centuries. The event was a whisper, not a shout. No tail of ice, no streak of light across the sky. Just a dark, dual-bodied system, a piece of the early solar system, performing a slow, gravitational dance in the black. We observed it with machines that cast artificial light. It observed nothing. It simply continued on its way, a silent testament to the clockwork nature of things on a scale that mocks human calendars.