How big is the universe?
The universe is a big, big place. But how big? And how
do we know?
Generations of explorers have looked very deep into
the expanse of the universe. And the journey continues today. The
distance from the Earth to the Sun has helped us to find the true scale of the
entire Solar System.
When we leave the Solar System, we find our star and
its planets are just one small part of the Milky Way galaxy. The Milky Way is a
huge city of stars, so big that even at the speed of light it would take
100,000 years to cross it all the way. All the stars in the night sky,
including our Sun, are just some of the residents of this galaxy, along with
millions of other stars.
Beyond our own galaxy lies a vast expanse of galaxies.
The deeper we see into space, the more galaxies we discover. There are billions
of galaxies, the most distant of which are so far away that the light arriving
from them on Earth today set out from the galaxies billions of years ago. So we
see them not as they are today, but as they looked long before there was any
life on Earth!
So how big is the universe? No one knows if the
universe is infinitely large, or even if ours is the only universe that exists.
And other parts of the universe, very far away, might be quite different from
the universe closer to home.
National Geographic presents a beautifully created CGI (Computer-Generated Imagery) documentary which takes us from Earth to the edge of the 'observable universe'.
Narrated by actor Alec Baldwin:
Enjoy the Prezi presentation:
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