Scientists gained information about the movement of objects in space by measuring the red shift of stars or galaxies. The red shift indicates that objects are moving away from us, providing evidence for the expansion of the universe. This discovery led to the development of the Big Bang theory, which describes the origins and evolution of the universe.
I don't think that "refreshing" is a common term in astronomy. If you mean "redshift", please ask a separate question.
The alterations to the electromagnetic spectrum caused by the expansion of the universe.
No. A red shift indicates that the object is moving away from the earth.
It's a change (decrease) in the frequency of the light we receive from the star. Equivalently, an increase in the wavelength. It usually means the star is moving away from us, though it might also be caused (usually to a lesser extent) by the star's gravitation.
It can tell us whether a star, or a galaxy, is moving towards us or away from us.
The frequency of light from a star is reduced (its wavelength increased) when the star is moving away from the observer. Red light has longer wavelengths than blue light. So the light from a star which is moving away from the earth appears to be redder than it actually was. This phenomenon is similar to the pitch of an ambulance siren dropping as it passes you and is moving away. The true spectrum for light from a star depends on the temperature of the star, but there are characteristic absorption lines (dark lines) in the spectrum which are specific to chemical elements which are present in the outer regions of the stars - such as hydrogen and helium. Light from within the star is absorbed by the atoms of these elements when they move from a low-energy state to one with a higher energy level. A comparison of where in the spectrum these lines appear to be against where they should be (for a stationary) star are a measure of the red-shift (or blue shift).
A red shift is observed if an object is moving away from the earth while a blue shift is observed if it is approaching the earth.
The red shift shows the velocity with which an object is moving away from the earth. The red shift of an object is correlated to its distance from the earth and so it is also a measure of the distance.
Briefly, redshift shows that most objects move away from us; this means that the Universe is expanding.