Tonight are the Geminids, a meteor shower caused by 3200 Phaethon. In classic Wisconsin fashion, this astronomical event will probably be obscured by clouds. (Argh!) But that won’t stop some of you from seeing a show that has been getting better and better through the years.
While viewers in Alaska and Asia will see the peak of the show, a crescent moon should allow dark skies that will make the meteors visible for viewers with clear skies.
Recent years have seen peaks of 120-160 meteors per hour. Geminid meteors move at a rather sluggish 22 miles per second. This, combined with their greater density, lead to easy-to-spot, slow-moving meteors, some of which are spectacular fireballs, breaking up and streaking throughout the atmosphere.
So how do you photograph such an event? First, find an area with a light pollution-free view of the east-northeastern sky. I like using a high ISO with a shorter shutter speed. This allows for the least burn-in of light pollution, lower noise values, and a more vibrant representation of the short-lived events that are space debris in our atmosphere.
Also aiding in light gathering is use of a wide aperture. I use f/4, because that’s the largest the 17-40L will get. If I had a faster wide angle, I would use it. Gathering the greatest amount of light in the least amount of time will give black skies with bright stars. For those looking to do star trails and meteor trails on digital, many short exposures can be combined to produce star trails containing any photographed meteors.
Tripod. One will be needed for meteors.
A wide angle will allow coverage of a great portion of the sky. Pre-focusing your lens at infinity, before dark, is a good idea. Use the distance scale on your lens (if it has one) if it’s after dark. Many lenses will focus “beyond” “infinity”, so cranking the focusing ring all the way to infinity will probably not lend very nice results.
Where to aim the lens? Put the radiant off towards a rule-of-thirds intersection and let the camera do its thing. You can point the camera at any area of the sky, but there isn’t really a guarantee on which area will be the most rewarding.
Some background on 3200 Phaethon: There is debate about whether 3200 Phaethon is an asteroid or a dead comet. The leading arguments tend towards an extinct comet that has picked up debris and become asteroid-like. The path 3200 Phaethon follows is elliptical, and extends towards the asteroid belt, just beyond Mars. Until we can visit 3200 Phaethon, we can enjoy the mysterious Geminid asteroid-meteor shower.
Some additional information:
Meteor Showers Online
NASA
