by J. Alex Knoll
Facing the Geminid Stream
Meteor for meteor, this should be a great show
The waning moon rises ever later in pre-dawn skies this week. Early risers can catch a final glimpse of the very thin crescent as it crests the southeast horizon Monday at 6am. Not 10 degrees to the east shines dazzling Venus, and Mars follows close behind, shining as bright as any star. Over the next hour, darkness gives way to dawn, with sunrise at 7:21, but you just might spot Mercury rising in the wake of Venus and Mars.
Moonless nights provide a dark backdrop for the Geminid meteors, which peak over a two-night period, Thursday evening and Friday before sunrise, then Friday night and Saturday early morning. Errant meteors will also streak through the sky for several nights thereafter.
Unlike other meteor showers, like the Perseids or the Leonids, records of which date back almost 2,000 years, the Geminids appeared suddenly in 1862. The newcomer produced at best a mere dozen shooting stars an hour. Ever since, however, that number has grown, until now the Geminids are one of the best meteor showers of all, delivering upward of 100 shooting stars an hour on moonless apparitions.
Astronomers searched more than 100 years for the source of the Geminids, but it wasn’t until 1983 that NASA’s Infrared Astronomical Satellite solved the puzzle. Unlike other meteor showers, which result from earth passing through a trail of debris boiled from the surface of icy comets as they orbit the sun, the parent of the Geminids is a rocky asteroid, 3200 Phaethon.
The meteors emanate from Gemini, high in the east by 10pm. Around 2am the constellation is directly overhead, and we’re pointing face into the Geminid stream, so the meteors can streak across the full sky in any direction.