Why is it that certain stars seem to glimmer with rapidly shifting
patterns
of color? Is it because of the atmosphere? I mean, some you can look at
and they just twinkle like normal but they seem to remain a white-ish
color,
where as others seem to be flashing all sorts of different colors (and no,
they're not UFOs or planes ). Anyone care to explain to this newbie?

There are primarily three different characteristics:

(1) Stars lower in the sky are viewed through more of the atmosphere. They
are going to twinkle more. The twinkling/color is going to be more extreme.

(2) Bright stars have more light for the atmosphere to twinkle with. (Please
note, these technical terms should not be used at home without professional
supervision).

(3) Stars are points. Planets show a disk. It is a tiny disk, and not
resolved by the eye, but it is still there. So in effect, a planet is a
bunch of points. Twinkling on any one point is going to be averaged in with
all of the other points. Twinkling from one point will zig while the next
point over zags. As a result, these two points counter each other. Average
it out and it is much harder to get a planet to do impressive twinkling.
(again, these are highly technical terms that should not be used by those
not licensed for their use)

So for most northern hemisphere observers, Sirius is going to look like a
multi-colored lightshow. Vega will give a less impressive performance but
still show some good twinkle/color while low on the horizon, but settle down
when it is overhead.

Hope this helps.

Chuck Taylor
Do you observe the moon?
Try the Lunar Observing Group
http://groups.yahoo.com/group/lunar-observing/
Lunar Picture of the Day http://www.lpod.org/
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