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How Big is The Universe


How Big is The Universe

         Our brains struggle to comprehend how big the universe is because everything here
 on Earth, and even the Earth itself, is very small when compared to the immense scale of
 the universe.
While we imagine light to be instantaneous, photons of light actually take time to travel from one side of the room to
 the other.So let's think about it a different way, using something we see and interact with every day… .
In the time it took you to read this far, a photon of light leaving the Sun has travelled about 10 million kilometres –
equivalent to travelling around the Earth 250 times.
Light that leaves our second nearest star, Proxima Centauri, takes just over four years to reach Earth and so we can
 define it as four light years away.
As such, if you were to look at Proxima Centauri, you would not be seeing the star as it is right now, but how it 'was' 4
years ago!
We see all things in the universe as they were in the past, whether they're on the other side of the room or the other
side of the galaxy.
To take this concept further, the nearest large galaxy to us is Andromeda which is so big and close that you can see
 it in the night sky with your .
What you're really seeing is 1,000's of billions of stars in a configuration similar to our Milky Way. However, all of
those stars are about 2.5 million light years away, which means you're seeing Andromeda as it was 2.5 million years
ago.



How big is the Universe?

The whole universe is littered with galaxies just like the Milky Way and Andromeda, and using our most powerful
telescopes we can see light from galaxies that has taken more than 13 billion years to reach us!

Since a photon of light left one of these galaxies, life sparked into existence and evolved. Dinosaurs ruled the Earth.
 Humans appeared, developed tools, art, science and technology, built the Hubble Space Telescope, put it into orbit
and finally stopped that poor photon on its 13 billion year journey!
The universe is about 13.8 billion years old, so any light we see has to have been travelling for 13.8 billion years or
less – we call this the 'observable universe'. HERE IS A VIDEO FOR UNIVERSE SIZE COMPARISON.
However, the distance to the edge of the observable universe is about 46 billion light years because the universe is
 expanding all of the time.
Imagine that a photon of light is emitted from a point on the edge of our .
While that  has been travelling through space, the universe has expanded. We have moved away from the
point where the light was emitted, and it has moved away from us!
Though the light might have only travelled for 13.8 billion years, the distance from us to the point it came from is, at
present, 46 billion light years!
So how big is our ? Well we don't really know, but it's big. So big that even light hasn't had time to cross it in
nearly 14 billion years! And it's still getting bigger all of the .

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