Grains Of Sand Vs Stars

Are at that place really more stars in our universe than at that place are grains of sand on all the beaches on World?

Information technology may hurt your brain to think near it, but it seems that the answer is likely to be yes, or at to the lowest degree the numbers are roughly in the aforementioned ballpark.

Astronomers really set out to answer this question about a decade ago. It's a tricky trouble to solve, but it's slightly easier if you throw in a couple of qualifiers — that we're talking about stars in the observable universe; and grains of sand on the unabridged planet, non just the beaches.

The scientists started by measuring the luminosity density of a section of the universe — this is a measurement of how much calorie-free is in that space.

They so used this measurement to judge the number of stars required to create that amount of low-cal. This was quite a mathematical challenge!

"You have to assume that yous can have one type of star represent all types of stars," says astronomer Simon Driver, Professor at the International Heart for Radio Astronomy Enquiry in Western Commonwealth of australia and one of the scientists who worked on the question.

"Then let's assume, on average, this is a typical mass star that gives out the typical corporeality of low-cal, then if I know that a portion of the universe is generating this corporeality of light, I can now say how many stars that would equate to."

Now equipped with an estimate of the number of stars within a section of the universe, the next challenge was to work out the size of the universe.

Given we know that the universe is thirteen.eight billion years old, we can assume that nosotros exist in a sphere 13.viii billion lite years in volume. But there'due south a grab: the universe is potentially infinite in size.

"We know that it has a finite age — we know information technology started thirteen.viii billion years agone — but spatially, in terms of its extent, it could be infinite," Driver says. However we also know that considering of its age, we exist in a bubble inside that infiniteness, and that bubble is called the 'observable' universe.

Later all these calculations and caveats, Driver and colleagues came up with a figure of seven followed past 22 zeros, or 70 thousand 1000000, 1000000, 1000000 stars in the observable universe.

That's 70,000,000,000,000,000,000,000 stars!

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So what near grains of sand on Earth?

"That was about harder to piece of work out than the number of stars," Driver says.

Luckily, someone suggested starting with the Sahara Desert, which is domicile to around one-half of all the grains of sand on Earth.

"That made it easier; I then merely had to work out how many grains of sand are in the Sahara, and I didn't have to worry almost every beach on the planet," Driver recalls.

He institute the full size of the Sahara, the average depth of sand across the Sahara and from that was able to calculate the estimate number of grains of sand in the Sahara.

"Once I got all that I could put all those numbers together and got a number that was remarkably shut to the effigy for the number of stars, but merely a little flake less," he says. "Information technology was nearly a factor of 10 smaller, but there's easily a factor of 10 error in both of those estimates and so information technology could only as easily be the other way around."

That's 70,000,000,000,000,000,000,000 stars versus 7,000,000,000,000,000,000,000 grains of sand!

So fifty-fifty though it's an impossible question to answer definitively, it seems that the listen-bending possibility of and then many stars existing in the universe is actually truthful.

Professor Simon Driver spoke with Bianca Nogrady

Be a denizen scientist Tin can you volunteer some time to be a citizen scientist? Visit Milky way Explorer and first classifying galaxies for astronomers as part of a real inquiry project. Go involved in August and you could win a wi-fi telescope. Schools' tin join in too.