The wavelength of light emitted by a moving object is shifted. To get it really right, you should understand the Special Theory of Relativity.
It tells us whether a star (or galaxy, or other object) is moving towards us, or away from us; and how fast.
It indicates how fast an object is moving away from us.
To find the speed of a star using Doppler shift, you can measure the change in the wavelength of light emitted by the star. If the light is redshifted, the star is moving away from us; if it is blueshifted, the star is moving towards us. By analyzing the amount of shift, you can determine the star's speed relative to the observer.
It doesn't. The Doppler shift can tell you how fast something is moving towards us or away from us; not how far it is. Only in the case of distant galaxies can this be used to estimate the galaxy's distance, because of the expansion of the Universe (galaxies that move away from us faster are generally farther away).
Actually, it wasn't the Doppler-effect that lead to the Big Bang theory, but the red-shift of remote galaxies. Although it was initially thought that this red-shift might be caused by a Doppler-effect, it is now understood that this red-shift is caused by the metric expansion of space itself.
It tells us whether a star (or galaxy, or other object) is moving towards us, or away from us; and how fast.
True
If there is no observable Doppler shift, then the star is probably not moving very fast. This refers to the component of the star's movement toward us, or away from us - the "sideways" part of the movement can't be determined by the Doppler effect.
A Doppler red-shift is a shift in recognizable features of a star's spectrum from the wavelengths where we know they belong toward longer wavelengths. Such a shift can be caused by the star's moving away from us, and that's how it's interpreted when astronomers see it. A Doppler blue-shift is a shift in recognizable features of a star's spectrum from the wavelengths where we know they belong toward shorter wavelengths. Such a shift can be caused by the star's moving toward us, and that's how it's interpreted when astronomers see it.
A blue-shift means an object is moving towards us, a red-shift means it is moving away from us. Blue-shift and red-shift are changes in frequency of the light we receive, due to the relative movement. This is called the Doppler effect.
They let us see the speed of the stars around the common center of mass. More precisely, the Doppler shift will only detect the component of this speed in our direction - that is, towards us, or away from us.
It indicates how fast an object is moving away from us.
There is a Doppler shift which results from the relative motion of the star in question, either toward or away from us as we observe it.
In that case, the star must be approaching us.
To find the speed of a star using Doppler shift, you can measure the change in the wavelength of light emitted by the star. If the light is redshifted, the star is moving away from us; if it is blueshifted, the star is moving towards us. By analyzing the amount of shift, you can determine the star's speed relative to the observer.
The Doppler shift can be observed when there is relative motion between a source of waves (such as sound or light) and an observer. This causes a change in the frequency of the waves detected by the observer, either increasing or decreasing depending on the direction of motion.
The Red Shift or Doppler effect