I've seen a few posts recently (and in the past) about "objects in the night sky that flash different colours". One of the more recent posts had a
link to a long exposure photograph
someone took of this phenomena
which was talked about on C2C.
Having seen this phenomena before, and photographed the occasional star, I thought I'd try to recreate the effect seen in photographs like the one
linked to above with a star that is well known to "flash various colours" or scintillate
"twinkle" - Sirius.
It was clear last night, and Sirius was twinkling fairly nicely, so I decided to set up a camera and have a go at photographing it. Visually, it
seemed to mostly be twinkling blues and greens. I didn't notice any strong red or orange.
I didn't have much time (dinner was smouldering) but I managed to take 16 shots with a long lens and a DSLR on a fixed tripod. I also only managed to
take exposures of 6.5 second length, even though I tried to change the exposure, but I was fumbling in the dark somewhat. I tried moving the camera
around a little differently each time to get a variety of results. The best shots are posted below.
First is a shot of Sirius where I did not attempt to move the camera. Exposure details: 6.5 seconds @ F4 (ISO 800).
I found Sirius in my planetarium software. It's the star that is at the top right hand corner of the "About Sirius" window in this screenshot.
I've identified and labeled the 4 brightest stars in the following crop of the first photograph I posted accordingly, so there can be no doubt the
bright object in the frame was Sirius :
A = Sirius
B = TYC 5954-737-1
C = TYC 5954-251-1
D = TYC 5953-3315-1
I zoomed in on my planetarium software a bit, and took this screenshot. As you can see, the four brightest stars in the previous image match up
Now that the identity of the object is confirmed, here are a few shots where I moved the camera around a bit during the exposure, to simulate the
camera shake that would be expected during a long exposure where the camera was hand held.
In this shot the colours came out quite nicely. Exposure details: 6.5 seconds @ F4 (ISO 800).
In this crop of the above image the colours can be seen a bit better.
In this shot I slightly defocused the lens, which resulted in this interesting effect. Exposure details: 6.5 seconds @ F4 (ISO 800).
Here's a crop of the above shot.
I think the effect matches very closely that seen in the C2C UFO photograph, keeping in mind that that photograph is probably at least 100% crop
(perhaps even enlarged beyond the original size).
Try it for yourself. You don't need an expensive camera or lens. Any camera will do pretty much. Some quite interesting effects can be achieved with
a little ingenuity, like this beautiful image which made NASA's APOD last year