How many miles is the universe across?

1 Answer
Dec 22, 2016

The observable universe is approximately #5.4xx10^23# miles in diameter.

Explanation:

In one second, light travels about #186000# miles (in vacuum).

There are #86400# seconds in each days, so in one day light will travel:

#86400 * 186000 ~~ 1.6xx10^10# miles

One year is approximately #365# days, so in one year light will travel:

#365*1.6xx10^10 ~~ 5.8xx10^12# miles

The observable universe is approximately #93# billion light years across, so:

#9.3xx10^10 xx 5.8xx10^12 ~~ 5.4xx10^23# miles

That's #540,000,000,000,000,000,000,000# miles