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BIO Magazine - The changing colours of the universe Δεκέμβριος 2015
Δεκέμβριος 2015 No38

BIO Space Sciences

The changing colours of the universe
The changing colours of the universe
We know we live in an expanding universe but it's also changing colour and has been doing so for billions of years.
Take a look at a Hubble image of the and you will see hundreds of that come in a variety of shapes and colours. So what are we seeing?

Stretching light

In our expanding , galaxies are rushing away from us at vast speeds. Nearby galaxies, only millions of light years from Earth, are speeding away at hundreds of kilometres every second. More distant galaxies, billions of light years away, are rushing away at speeds in excess of 100,000 kilometres every second.

A natural consequence of this rapid expansion is the stretching of light via the Doppler Effect.

This stretching of light is similar to the stretching of here on Earth. The pitch of the sound from a motorcycle is lowered as it moves away from you. Just as sound waves are stretched (lower pitch) as a motorcycle races away, the are stretched (redder light) as a races away.

When we look at distant galaxies, we are looking into the past, as light can take billions of years to travel across the universe. This presents an opportunity for astronomers to directly observe the ancient universe.

http://phys.org/news/2014-04-colours-universe.html

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