Posted on 07/17/2011 5:29:45 AM PDT by SunkenCiv
Explanation: You could be the first person ever to take a real single-exposure image like this. The above image from Vienna, Austria is not real in the sense that the 360 degree star trails in the sky appear only because of a digital trick. Real star trails observed above Vienna could never go 360 degrees around because the Sun would rise at some time during the exposure and dominate the frame. Star trails of any length occur because as the Earth spins on its axis, the sky seems to rotate around us. This motion, called diurnal motion, produces the beautiful concentric arcs traced by stars during long time exposures. Towards the middle of the above digitally stretched picture is the North Celestial Pole (NCP), easily identified as the point in the sky at the center of all the star trail arcs. The star Polaris, commonly known as the North Star, made the very short bright circle near the NCP. Walter Lewin, though, has asked APOD to pose this as a challenge to astrophotographers: create a real single-exposure image of a clear night sky that features 360 degree star trails. Of course, such an image would only be possible near the poles of our fair planet, because only there could a nighttime run for more than 24 hours.
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[Credit & Copyright: Peter Wienerroither (U. Wien)]
I’ll be forced to pass.
didnt i see that at the start of that old tv show time tunnel?
Seems to me that the real trick would be replacing batteries every couple of hours without moving the camera.
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Photoshop - it’s the only way to go.
LOL! Time travel. This photo for the Astronomy Picture of the Day does not exist yet. Please make one for us. — NASA
I didn’t get a 360 degree pic, but I did get an interesting similar shot of star trails when I was about jr. high school age. Got my dad’s Speed Graphic 2 1/4 x 3 1/4 on the tripod, climbed up on the roof of the house just after dusk and set it up. Opened the shutter, climbed back down and went to bed. Got up before dawn and climbed back up to close the shutter and get the camera off the roof.
When I developed the sheet of film - from a film pack, no less - I had a nice semi-circle of star trails. It was fascinating. Wish I still had that piece of film. Still got the camera, though. And the wooden tripod. [ grin ]
What if you left the camera set up for an entire year, pointed at the north star, and just opened up the shutter for a minute or so at the same time every night?
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