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A light-year is
the distance that light travels in one year. Since light moves at just over 186,000 miles per second, it travels about 6.2
trillion miles in one year. For a speed you can relate to, if you could
travel at the speed of light in your car, you would circle the earth seven
times in one second!
When you look up into
the night sky, you are only seeing a small part of the stars in our own
Milky Way. To see our nearest neighbor, the
Andromeda Galaxy and other galaxies, you
need a telescope or strong binoculars. Andromeda is 13
quintillion miles away (2.3 million light-years), so traveling at
the speed of light, it would take 2.3 million
years to get there. Then consider that there are billions of galaxies millions of times further
than Andromeda and you can begin to realize the incredibly vast size of our
Universe.
To relate to the speed
of light, consider this: Our current fastest rockets travel at 25,000 miles per hour.
The speed of light is 26,000 times faster than that. So if you could build a spaceship that could travel at the speed of light,
look how long it would still take you to travel to the
following places.
You could circle the earth 7 times in 1 second.
You could reach the moon in 2 seconds.
You could reach Mars in 3 minutes.
You could reach the sun in 9 minutes.
You could reach Jupiter in 1 hour.
You could reach Pluto in 4 hours.
You could reach the nearest star in 4 years (in our own Milky Way galaxy).
You could travel across our Milky Way galaxy in 150,000 years.
You could reach the nearest galaxy, Andromeda, in 2.3 million years.
Difficult to conceive, isn't it?
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