# Are There More Stars In The Universe Than Grains Of Sand On Earth?

Tuesday, 26 November 2013 - 2:07PM
Tuesday, 26 November 2013 - 2:07PM

People come out with all kinds of outlandish 'facts' about the incredible size of our universe, but thanks to Carl Sagan, none of these statements are as common as this old doozy:

"There are more stars in the universe than there are grains of sand on Earth".

It seems impossible doesn't it? The universe is huge, but when you consider how many beaches there are on this planet and how miniscule a grain of sand is, it makes you think that in this instance at least, Carl Sagan was maybe taking a bit of poetic license with his statement? Thankfully for my tiny brain, Fraser Cain of 'Universe Today' has taken a stab at answering this question once and for all. *Warning: Mind-boggling numbers ahead*

Cain starts with the estimate that on average, there are approximately 100 to 400 billion stars in a galaxy. There are estimated to be around 100 billion galaxies in our universe, which a means that a bit of large format Math tells us there are approximately 10 sextillion (10 billion, billion) stars in our universe. To put that into perspective, let me show you what 10 sextillion looks like written down:

10,000,000,000,000,000,000,000

Now of course, this is just an estimate. There could actually be upwards of 200 sextillion stars in the universe, there just really is no way of saying for sure. But for the purposes of this investigation, 10 sextillion is the magic number used by Mr.Cain, who now moves on to estimate the number of grains of sand on Earth's beaches...

Around 8,000 grains of sand can be packed into one cubic centimeter, which according to Mr.Cain means that 10 sextillion grains of sand placed in a ball would create a sphere with a radius of 10.6 kilometers. According to Cain's associate, 'The Math Dude', there are approximately 700 trillion cubic meters of beach on our planet. These 700 trillion cubic meters could therefore hold approximately 5 sextillion grains of sand, which means that Carl Sagan was, of course, correct.

Cain admits that these are just mathematical estimates and there is of course no way of confirming this notion with 100% certainty, but for now at least, if you want to wow your friends down the pub, feel free to use this fact safe in the knowledge that it is at least, probably correct.