Unformatted text preview: is a positive number. The spectral lines appear shifted to the red end of the spectrum, so the shift is called a redshift . If the star is moving toward you, then the wavelengths appear to the compressed and is a negative number. The spectral lines are shifted to the blue end of the spectrum, so the shift is called a blueshift . The doppler effect tells you only about the motion relative to you. If you move toward the star or it moves toward you, the doppler effect will be the same. The Earth is in motion relative to the star because it are orbiting the Sun, so you have to take the Earth's orbital motion into account when figuring the star's velocity from the doppler effect. Also, the doppler effect gives you only the speed along the line of sight. Most stars move at an angle to our line of sight. The part of a star's total velocity that is perpendicular to the line of sight is called the tangential velocity ....
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- Fall '10
- Astronomy, Velocity, Redshift, Spectral line