# Red Shift

Red Shift
“Red Shift” happens whenever a light beginning moves away
from an observer that the most distant objects in the Universe.

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Red Shift

• when distant galaxies are moving away from Earth – the light waves giving off to stretch out behind them; because of little light wave is being sent from a little further away.

Red Shift
This is how we will discover the most distant galaxy.

• when the light waves from distant galaxies are stretched out in this way – they look redder – this is called red shift.
• the increase of red shift with distance proved that the Universe is growing bigger.
• only nearby galaxies show no red shift at all.
• the most distant galaxies have red shifts around up to seven (Clusters of galaxies)
• “Red Shift” can be caused by the expansion of the Universe – gravity or effect of relatively.

Direct evidence of acceleration
from a distance modulus–red shift graph.

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Astronomers

• Christian Doppler  – Red Shift was first described by Austrian mathematician in 1842. (wikipedia: Christian Doppler)
• Edwin Hubble  –  he showed that a galaxy’s red shift is relative to its distance – further away galaxy is the greater its red shift and the faster it must be zooming away from Earth; this is known as Hubble’s Law. (Wikipedia: Edwin Hubble)
• The Hubble’s law establishes that the speed at which a galaxy is moving away is directly proportional to its distance.

## v = Ho . D

v is the speed of the galaxy (in km/s)
Ho is the Hubble’s constant (in 2006 it was estimated in 70 Km/s/Mpc).
D is the distance between the Galaxy and the Earth (in megaparsec: Mpc)

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