On September 3, Bill Yeung, an amateur astronomer from El Centro, California, discovered a fast-moving object in the sky. He sent the measurements to the Minor Planet Center (MPC), believing that he had discovered a near-Earth asteroid. It was temporarily named J002E3.

A few days later, the MPC discovered the object was actually travelling in a large, 50-day orbit around Earth, not the sun. It was still unidentified – space junk, a second natural moon, or a captured asteroid?

Over a hundred measurements later, Paul Chodas from the NASA/Jet Propulsion Laboratory believes that J002E3 is probably a Saturn V rocket stage from one of the Apollo moon missions. It is probably from Apollo 12, launched on November 14, 1969. The rocket stage was captured by the Earth-Moon system in April 2002, after drifting in a solar orbit since March 1973.

The object is 18 meters, or about 11 miles long. The infrared spectra of the object closely matches the white paint used on the Apollo rockets. The spectrum is very different than an asteroid.

The Earth-Moon orbit that J002E3 is in isn’t stable. By July 2003, it will return to a solar orbit and back to the Earth-Moon orbit in about 30 years. There is a 1% chance that it will crash into the moon during this encounter. Over the next several thousand years, it will hit the moon or burn up in Earth’s atmosphere.