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Taras R. Hnatyshyn
{K:4055} 6/16/2004
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Richard, (and Jim),
Though the stars are affected by the Doppler effect, the colors have more to do with the star's temperature and stage of evolution. See http://www.mira.org/fts0/stars/114/txt001w.htm for an explanation.
Taras
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Jim Goldstein
{K:21230} 6/16/2004
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As they say you learn something every day. Very good to know. Thanks for the info!
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Richard Lyne
{K:15} 6/16/2004
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Hi Jim.
The red and blue stars are down to the doppler effect.
With stars that are moving towards the Earth there is an increase in frequency of lightwaves (they are effectively compressed by the motion of the star) resulting in a decreased wavelength (which is why they are seen as blue).
The stars you see as red are moving away. They have an increased wavelength because the frequency of the lightwaves is reduced.
Science aside this is a really good photo, and I agree with you Jim that the trees add that extra human dimension to a celestial image.
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Kiarang Alaei
{K:49415} 6/16/2004
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Splendid shot. magic symmetery. great work. it has a wonderful rhythm in composition. i enjoyed it and decide to show your photo as a technical photograph to my students in photography class. bravo!
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Roberto Arcari Farinetti
{K:209486} 6/16/2004
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woow another my congrats.. the main is all for you..
the mine is the first comment.. so..
I would have to subject to you a photo if you love astronomy...
roby
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Michele Lostia
{K:1126} 6/16/2004
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Featured Critique of the Day... for one own's photo! I never thought of that possibility :)
The effect is very good, not only in showing the rotation of the Earth, but also the different colours of the stars. Good job.
In reply to Bill and Irenka, the amount of "movement" you get in those 15 mins is an angle of 3? 45': the Earth rotates 360? in 24 hours; with 96 quarters of an hour in one day, you get 360 / 96 = 3.75.
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Irenka Daniluk
{K:8011} 6/16/2004
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Excellent shot, amazing that you got such an effect of movement in only 15 minutes!
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Taras R. Hnatyshyn
{K:4055} 6/10/2004
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Simon,
Most satellites are pretty dim, so they only leave a faint trail. Some planes can be quite annoying. I once had 6 planes in a wide-angle planetary alignment photo I took. Then again, that's what one gets for trying astrophotography from the heart of New York City. If the planes are far enough away, then they're not as big a problem. On a guided astrophoto, you can at least cover the lens during the plane's overflight. With a star trail photo this would leave a gap in the trails. Then again, this can be used to goo effect at times...
Taras
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Simon Crinks
{K:-54} 6/10/2004
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Satellites and planes in star trail pics, good or bad? - discuss.
Personally I think they're fine. It's not the same as pylons in landscape pics...
Excellent star trail pic here, by the way, well done.
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Jim Goldstein
{K:21230} 2/11/2004
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I have mixed feelings about satelites and planes traveling through my photos. Whats your take? Again great star trails. Very interesting lighting. Your stars seem to have a red, white and blue look to them. I actually like the inclusion of the tree tops. It adds to the dimension of your image. A little more tree tops would be nice.
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Bob Smith
{K:2340} 11/11/2003
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Very nice shot. Thanks for your advice on how to do this myself.
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Taras R. Hnatyshyn
{K:4055} 5/18/2003
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Bill,
The dot in the lower right is an airplane strobe. That is in the line of an airplane trail. The satellite is a faint diagonal line near the center of the photo. There is an orange streak in Camelopardalis on the left edge, which I have no idea what it is--my first "UFO"?
Taras
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Bill Ciavarra
{K:10216} 5/18/2003
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Very cool how much motion there is in 15 mins.. I assume the satellite is the white dot at the lower right..guess it's moving with the earth...intresting.
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Roberto Arcari Farinetti
{K:209486} 5/13/2003
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great effects of rotation...
good shot...
ciao roberto!
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