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Old Apr 18, 2005, 4:38 PM   #21
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Well, from what I've learned from the Astronomy Master Classes I've followed, I do think it does matter.

It's main cause is the parallax effect. The further objects are from the subject, the less they move, the smaller their angle of movement is. This is how the distances of stars are being calculated.
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Old Apr 18, 2005, 5:50 PM   #22
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[color=aqua]Ok ok...but the distances are soooo far, that the depth is not percieved by our eye (or camera). The sky and stars do move in position due to the earths rotation and elliptical trip around the sun, and the stars are ever moving though the galaxy and universe(taking millions and billions of years to do so). Though the our galaxy and universe is 3 dimensional, our eyes see it much more as 1 dimensional when looking into the sky from earth.

Think of it this way, all the constellations...lets say the little dipper and the big dipper, would change form and be unrecognizable if you guy's theory was true, becauseall the stars (in those constallations) are at very different distances from us. This would of been bad years ago, as the two stars at the end of the bowl of the Big Dipper are called the "Pointer Stars" because a line drawn between them points to Polaris, the North Star. Now if the stars move asynchronous from each other, all the sky would be outta of whack and everone on boats or on land that navigated by the stars would be lost!

The only star that really doesnt appear move is the North Star, as all others rotate in the sky around it. (The stars of course dont move, but its the earths rotation.

Stars do have random motions, they don't orbit the galaxy in exact circles. The random motion usually equals to 10 miles or so in a direction...undetectable with the eye in one nite!

There are some objects in the sky that will go against normal movement, in opposite directions that can be mistaken for stars...such as planets.

I think you are wrong. For example the Sun rays will reach Earth in about 8 minutes. So travel from Earth to Sun is 8 minutes(speed of light)long. So the further the star is, the longer it will take it to "move". Its like in broadcasting, you have actual event, and if you are broadcasting it,the transmition is slower. Same in space.
I cant even begin right now to explain this, but you are sorta right in a small way, but wrong! Think of this one this way since I cant in a short sentence or two explain it now...

The light reflected off the moon reaches the earth much faster than off the sun (in a few seconds compared to several minutes). When both are in the sky at dusk or dawn, dose the moon haul bottom across the sky just because the light has a shorter distance to travel? No. Its sort of a bad example, but you get the idea.

As for calculating star distance...Nearby stars are measured with parallax, needed are 2 measurements of the star's exact position in the sky. These readings are then taken on opposite sides of the earths orbit,6 months apart. From this triangulation, the star distance is found.

For farther star distances a indirect method is used. The Cepheid variable technique is used out to millions of light-years. Cepheids are a type of star whose real brightness is known. If a Cepheid appears dim its distance thus can be estimated, sort of like if you see a flashlight down a long hallway that is dim, you know its far, but when the flashlight is close, its bright!

Lets get back to cameras now!

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Old May 8, 2005, 9:33 PM   #23
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Not to bring this subject up again...but here is a real pic of a 10 min exposure of the night sky.

This was not taken by me, but posted in another forum by another!

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