Post by pook on Dec 9, 2006 14:46:17 GMT
Hi All,
I have attached below some comprehensive information on the Geminid shower prepared by Terry M. Hope you find it useful.
GEMINID METEORS SET TO DAZZLE!
The Geminids are almost always the best of the annual meteor showers. As the name implies, they appear to come from the constellation Gemini, which is high up in the SE late on December evenings. The radiant, or point in the sky from which they appear to come if you trace their paths backwards, lies just above the star Castor, the higher of the two bright stars marking the Heavenly Twins.
You can start to see the first Geminids in the late evenings from about December 8, but activity starts to pick up about the 10th, building to the maximum which this year will be in the early hours of December 14. In other words, you'll see most meteors late on the night - in fact just before dawn! - of December 13-14. Activity will then decrease sharply, with few being seen after the 15th.
Meteors are tiny specks of debris from comets, and become visible only when they collide with Earth's upper atmosphere at very high speed, and burn away in a streak of light. But the Geminids are unusual, because they appear to come from an asteroid, 3200 Phaethon, not a comet. They are also slightly unusual in two other respects:
(a) They have relatively low collision speeds with the Earth - 'only' about 35 km/sec.
(b) they have a higher than average particle density - about 2g/cm3, compared with about 0.3 g/cm3 for the Perseids. That perhaps reflects their 'rocky (?) origin....
The Earth only started to encounter the Geminid meteor stream in the mid-19th century. It was first reported by Robert P Greg of Manchester in 1862. Acticity gradually increased over the years with hourly rates of 50-60 in the 1930s. Recently, Zenithal Hourly Rates have sometimes exceeded 100. The Earth will no longer encounter the Geminids in about another 100 years, so observe them while you can! It could be that the shower will get richer still before starting to decline, or it may already be at or near its peak - there's only one way to find out!
The low collision speed, and higher density, means that Geminids often last longer than other meteors before extinction, and that, combined with their slow speed, makes them good photographic candidates. Bright ones sometimes break up unto a chain of fragments all travelling along the same path. Geminids are, on average, brighter than most shower meetors, so they're a great shower to watch in good conditions.
Moonlight does not really interfere this year, so if we are blessed with a clear sky that night we will see some nice free celestial fireworks! But please note that you will see very few meteors from brightly lit city areas, and even the light from moderate sized towns will spoil the view significantly. To see them at their best you must get well away from all bright lighting - the darker the sky the better. If you can see the Milky Way really clearly, that's a good indication.
Some Geminids will be visible from about 7 or 8 p.m. onwards each night, mainly from 10 - 15 December, but the real peak will be just before the first glimmer of dawn on Thursday 14th. If you have very clear dark skies then, you might see as many as 100 meteors per hour!
So keep your eyes open and skywards on the night of 13/14 December if it's clear!
Terry Moseley.
I have attached below some comprehensive information on the Geminid shower prepared by Terry M. Hope you find it useful.
GEMINID METEORS SET TO DAZZLE!
The Geminids are almost always the best of the annual meteor showers. As the name implies, they appear to come from the constellation Gemini, which is high up in the SE late on December evenings. The radiant, or point in the sky from which they appear to come if you trace their paths backwards, lies just above the star Castor, the higher of the two bright stars marking the Heavenly Twins.
You can start to see the first Geminids in the late evenings from about December 8, but activity starts to pick up about the 10th, building to the maximum which this year will be in the early hours of December 14. In other words, you'll see most meteors late on the night - in fact just before dawn! - of December 13-14. Activity will then decrease sharply, with few being seen after the 15th.
Meteors are tiny specks of debris from comets, and become visible only when they collide with Earth's upper atmosphere at very high speed, and burn away in a streak of light. But the Geminids are unusual, because they appear to come from an asteroid, 3200 Phaethon, not a comet. They are also slightly unusual in two other respects:
(a) They have relatively low collision speeds with the Earth - 'only' about 35 km/sec.
(b) they have a higher than average particle density - about 2g/cm3, compared with about 0.3 g/cm3 for the Perseids. That perhaps reflects their 'rocky (?) origin....
The Earth only started to encounter the Geminid meteor stream in the mid-19th century. It was first reported by Robert P Greg of Manchester in 1862. Acticity gradually increased over the years with hourly rates of 50-60 in the 1930s. Recently, Zenithal Hourly Rates have sometimes exceeded 100. The Earth will no longer encounter the Geminids in about another 100 years, so observe them while you can! It could be that the shower will get richer still before starting to decline, or it may already be at or near its peak - there's only one way to find out!
The low collision speed, and higher density, means that Geminids often last longer than other meteors before extinction, and that, combined with their slow speed, makes them good photographic candidates. Bright ones sometimes break up unto a chain of fragments all travelling along the same path. Geminids are, on average, brighter than most shower meetors, so they're a great shower to watch in good conditions.
Moonlight does not really interfere this year, so if we are blessed with a clear sky that night we will see some nice free celestial fireworks! But please note that you will see very few meteors from brightly lit city areas, and even the light from moderate sized towns will spoil the view significantly. To see them at their best you must get well away from all bright lighting - the darker the sky the better. If you can see the Milky Way really clearly, that's a good indication.
Some Geminids will be visible from about 7 or 8 p.m. onwards each night, mainly from 10 - 15 December, but the real peak will be just before the first glimmer of dawn on Thursday 14th. If you have very clear dark skies then, you might see as many as 100 meteors per hour!
So keep your eyes open and skywards on the night of 13/14 December if it's clear!
Terry Moseley.