Event driven astronomy
[21] Wolfe Creek Crater in western Australia is on average 875 metres in diameter
(Sir Patrick Moore).
[22] A Kappa Cygnid meteor streaks across the sky.
[23] A bright Perseid Meteor streaks through the sky near the Pleiades open clust.212322mile-wide crater – the atmosphere was eerie. There is no crater quite
as impressive as this one. At one stage efforts were made to dig up the
meteorite but most of it was probably vaporized away during its plunge.
Another meteor crater, Wolfe Creek in the Northern Territories of
Australia is in a very deserted part of the country. However, once you get
there it is well worth seeing.
We have to admit that the impact of a large meteorite say half a mile
across would cause immense damage if it landed in a populated area and
could wipe out a city. There must have been major impacts in the past
and there is wide support that 65 million years ago the meteorite that
landed in the Yucatan peninsula changed the climate to such a degree that
the dinosaurs died out.
Meteors are relatively easy things to photograph with a DSLR camera
as long as luck is on your side. A DSLR set on a standard tripod using
a relatively wide-angle lens and a shutter release cable is all you need.
The lens should ideally be 50mm or shorter in focal length. Typically,
something around the 18-28mm focal length is ideal for a non full-frame
DSLR camera. The ISO needs to be set high, typically 1600-3200 and the
lens aperture fully opened. The faster the lens, the better and f-ratios of
f/1.8 – f/2.8 are recommended if available. Prefocus the lens at infinity
and turn auto-focus off. Set the exposure time to say 30s and set the
camera’s shooting mode so that it repeats shots if the shutter button is
held down (burst shooting). Lock the remote shutter release in the on
position and then just sit back and wait.
The best place to point the camera is typically about 60° up in the
sky and roughly 45-60° to either side of the radiant. Actually, this is less
critical and great shots can be had by pointing the camera at the radiant
itself. However, trail lengths appear longer the further they occur from the
radiant. Consequently, any shower meteors which are caught close to the
radiant will appear quite short.
You’ll need a decent sized memory card to store all the photos you
take throughout a meteor photography session and make sure you have
plenty of charged camera batteries on standby too. Finally, when done,
the only way to check whether you’ve been successful is to download
the shots to a computer and si through them one by one. Laborious
though this is, just one bright meteor in a shot can make the whole task
completely worthwhile!