Once in a rare while, the Moon drifts precisely between Earth and Venus, erasing the brightest planet from the sky as if the night itself is demonstrating the mechanics of the cosmos. On September 14, much of Thailand will have an unobstructed seat for this celestial sleight of hand — a one-hour disappearance requiring nothing more than a clear western horizon and the willingness to look up. Thailand's National Astronomical Research Institute has taken the occasion as an invitation to gather the public, opening four regional observatories free of charge, honoring a tradition as old as astronom