The Immensity Of The Universe

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Photo courtesy NASA.

The Age & Size Of The Universe

It's impossible for us to really grasp with our human minds just how enormous the universe is. Below is a brief summary of the facts about the visible universe astronomers have been able to observe and calculate.

The best estimate of the age of the universe is 13.798 ± 0.037 billion light years. Because the universe is expanding ever since the Big Bang, we are observing objects that were originally much closer but are now considerably farther away than a static 13.8 billion light years distance.

The diameter of the observable universe is estimated at about 93 billion light years. So the furthest edge of the observable universe is about 46–47 billion light-years away.

The diagram below shows a timeline of how the universe has developed since the Big Bang.

440px CMB Timeline300 no WMAP

The Speed Of Light & The Size Of The Universe

Our galaxy, the Milky Way, contains up to 400 billion stars. In the observable universe, there are more than 200 billion galaxies (some estimates put this figure at up to 500 billion) – each with billions or even trillions of stars within it. This means there are roughly 100,000,000,000,000,000,000,000,000,000 stars in the observable universe.

The distance between galaxies, stars and planets is measured in light years - that is the number of years it takes for a beam of light travelling at 186,282 miles per second (299,792 kilometers per second)  to reach us on earth. In miles per hour, light speed is, about 670,616,629 mph. If you could travel at the speed of light, you could go around the Earth 7.5 times in one second. 

The light-year is a unit of length used to express astronomical distances and measures about 9.5 trillion kilometres or 5.9 trillion miles.  A light-year is the distance travelled by a beam of light through the vacuum of space in one year.

1 Light Year = 9,461 trillion kilometres = 5,878 625 trillion miles

Space Travel In Light Years

Alpha Centauri is the nearest star system to our sun at 4.3 light years away. That’s about 25 trillion miles (40 trillion km) away from Earth – nearly 300,000 times the distance from the Earth to the sun.


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