I was 10 or 11 years old when our teacher, Mr Brown, told us, “There are more stars in the sky than all the grains of sand on all the world’s beaches.”
We gasped. Huh? Pardon? Could you say that again?
Donald Duck comics were our go. We loved them. Could understand them. Fun. Easy.
The brainy kids could even make sense of the Phantom, the ‘Ghost who Walks’ (another comic book).
And the really brainy ones (the nerds) were beyond comics; they were into novels.
100 was Don Bradman’s batting average (well, close enough), 1000 was uttered as part of the title in Jules Verne’s famous ‘20,000 Leagues Under the Sea’ and a million was the amount of dollars mega-rich Americans had.
Big numbers for a little kid to get his head around.
But this ‘number of stars’ stuff was ..well ..almost scary!
“Um, how do they know that, Mr Brown?” I think I asked.
Stars give off light, some of which finds its way into lenses of powerful optical telescopes built on top of hills.
By pointing their telescope to a small section of the night sky astronomers can see many thousands of stars.
Then they turn the telescope to another small part of sky and see thousands more.
“There are radio telescopes too, and they work a bit differently. Stars give off pulsating electromagnetic signals which aren’t visible to the eye but are ‘captured’ by the telescope (which is sometimes shaped like a big dish)
“Wow. But how could they count as many stars as there are grains of sand on all the beaches of the world?”
You see, it’s not just about counting, it’s about estimating.
Scientists working in countries all around the world examine different parts of the sky. They collect their information and share it with one another. Then they’ll say something like, “All of us together can see into this small fraction of the universe and we see about this many stars there. So if we could see into the entire universe the number of stars should be about ……”
Many years later I learnt that modern radio telescopes can detect stars that are more than 100 nonillion kilometres away.
That’s 100 000 000 000 000 000 000 000 000 000 000 km beyond planet Earth.
Lots and lots of grains of sand are not too difficult to imagine ….(we all know what a grain of sand looks like).
But here’s another way to get an idea of the number of stars out there (yes, ‘out there’, not ‘up there’ ….there are billions and billions of stars below our spherical planet, as well as out to the sides.
Are you ready?
It is said that there are more stars in the universe than all the sounds ever made by every person who’s ever lived!
Some things are simply unimaginable ….we just can’t get our brains around them ….the number of stars out there certainly belongs in that category.
In the next blog we’ll talk about a number so huge that it makes the amount of stars in the universe seem tiny.