Sunday 9 December 2012

The Geminid Meteors.

The Geminid Meteors peak each year on or around the night 13-14 December radiating from a point in the constellation of Gemini. They are visible from around the globe, but are harder to observe in the southern hemisphere, since Gemini does not rise far above the horizon at this time of year. They were first observed in 1860, and have apparently been gradually getting brighter each year since then, leading some scientists to speculate that the path of the meteor shower might have recently been perturbed by the planet Jupiter, shifting it into the Earth's path.

The point of origin of the Geminid Meteors. Meteor Showers Online.

Oddly for a meteor shower, the Geminids do not appear to be related to a comet, but instead are associated with an object called 3200 Phaethon, which is classed as an Apollo Asteroid (an asteroid with an orbit that crosses that of the Earth). 3200 Phaeton has a highly elliptical orbit, which takes it in as close as 0.14 Au (14% of the distance between the Earth and the Sun, more than twice as close as Mercury) and out as far as 2.4 AU (2.4 times as far from the Sun as the Earth or 1.6 times as far as Mars). 3200 Phaethon does not appear to produce any sort of halo (a cloud of material produced by the evaporation of gas ice from the surface of a comet, thought to be the source of most meteor showers); rather it appears dark in colour an is classed as a B-type Carbonaceous Asteroid, thought to have a surface covering of  anhydrous silicates, hydrated clay minerals, organic polymers, magnetite, and sulphides.

The orbit of 3200 Phaeton. Image created using the JPL Small-Body Database Browser.

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