How Big is the Universe?

Space is too huge that humans find it difficult to sense it’s humongous size. The units to measure earthly distances wont quite works for cosmic distances. Distance within Solar System is often measured in Astronomical Unit (AU). It is the distance between Sun and Earth. Even AU becomes less helpful when the distances get much larger. In that case, the unit Light Year, comes to the rescue. (Parsecs are also used. 1 Parsec is 3.26 Light years) Light Year is the distance, light travels in a year. Remember, light travels 299,792,458 metres in a second. These are mind boggling distances, completely foreign to our day-to-day experiences, making it hard to grasp the size of this vast Universe. The easy way to tackle this is to make an analogy for the large distances with smaller ones that we can easily relate. Here’s a trick,

1 light year = 5.879 x 10¹² miles

1 AU = 9.296 x 10⁷ miles

5.879 x 10¹² miles / 9.296 x 10⁷ miles = 63242.25

That implies, 1 light year equals around 63242 AU.

And 1 Mile comprises, 63360 inches.

Thus we can take inch - Mile analogy for AU - lightyear relation.

With this relation, you can get a better grasp on the distances of the vast Celestial objects. Now lets consider, Sun and Earth are 1 inch apart, then a light year would be exactly 1 mile. Then Jupiter would lie 5.2 inches away and Pluto around 40 inches away. In this analogy, the nearest star, Proxima Centauri is roughly 4.2 miles away. The star Vega would be 26 miles away, Orion Nebula 1340 miles away, and the globular cluster M15 some 25,000 miles distant (about three times the diameter of the Earth).

On this massively compressed scale, the diameter of the Milky Way Galaxy itself would be about 100,000 miles. And to prove human’s miserable sense of scale, the radius of the observable universe would be 46.6 billion miles. Still finds it hard to imagine huh?

Puny humans!!

Credits : Wikimedia commons / Dave Jarvis