As usual at this time of the year, the Earth is entering a stream of debris from rock comet 3200 Phaethon, which is the source of the annual Geminid meteor shower. Forecasters expect the shower to peak on Dec. 13-14 with as many as 120 meteors per hour.
This year the nearly full Moon will reduce the number of meteors you may see but it is still well worth a look. Expected to peak from about midnight Friday Australian Eastern Daylight Time (or 1300 UT) until 9pm (1000 UT) Saturday, this meteor shower will be visible in both hemispheres.
Though you do need to keep in mind that meteor showers often peak hours before or after predictions and for sure we certainly don’t know everything that a given meteor stream might have in store!
This shower is an interesting one though, with an equally interesting history and source. The Geminids were first identified as a distinct meteor shower by R.P. Greg of Manchester UK in 1862, and the estimated ZHR rose from about 20 to 80 through the 20th century. The parent source of this shower remained unknown until 1983, when astronomer Fred Whipple linked them to the strange “rock-comet” body 3200 Phaethon. This is an Apollo asteroid also thought to be a member of the Pallas family of asteroids, 3200 Phaethon seems to be shedding enough material to produce the annual Geminid meteor shower. This makes the annual shower rare as one not produced by a comet. It’s worth noting that 3200 Phaethon also passes extremely close – 0.14 AU – from the Sun at perihelion, and gets periodically “baked” during each 1.4 year passage.
In the 21st century, rates for the Geminids have stayed above a Zenith hourly rate (ZHR) of 120, now the highest of any annual shower. It’s worth noting that an extrapolated ZHR of almost 200 were seen in 2011 when the Moon was at an equally unfavorable waning gibbous phase! The Geminids always produce lots of fireballs, capable of being seen even under moonlit skies.
With our warmer nights down under it is a great time to get out and have a look! Jupiter is also looking good after about 10:30pm and Mars and Saturn are visible in the early dawn skies as well.