# The Naked Scientists Forum

### Author Topic: Can one estimate how many stars there are in the universe?  (Read 479 times)

#### Alan McDougall

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##### Can one estimate how many stars there are in the universe?
« on: 28/06/2016 22:49:50 »
Can one estimate how many stars there are in the universe?

Give it a go

Alan

#### chris

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##### Re: Can one estimate how many stars there are in the universe?
« Reply #1 on: 28/06/2016 23:29:17 »
Yes, there are about 100 billion stars in our galaxy, and about 100 billion galaxies; so 1011 x 1011 = 1022 stars in the Universe. To give it its fancy name, that's ten sextillion, or so, otherwise known as a lot...

#### Alan McDougall

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##### Re: Can one estimate how many stars there are in the universe?
« Reply #2 on: 29/06/2016 02:17:46 »
Yes, there are about 100 billion stars in our galaxy, and about 100 billion galaxies; so 1011 x 1011 = 1022 stars in the Universe. To give it its fancy name, that's ten sextillion, or so, otherwise known as a lot...

Put another way

Quora Digest

Let's use some round numbers to get a feeling for this. There are about 300,000,000,000 3x10^11 or three hundred billion stars in our galaxy, and that number due to the red dwarfs might be as much as 3x as large.

There are on some estimates about the same number of galaxies in the universe. On the lower range then, we have about 10^23 stars in the universe or even something around Professor Dokkum's recent estimate.

That's about 50 stars in our galaxy for every person alive on earth, and the same number of galaxies per person: a lot of real estate any way one slices it. Leaving dust out of it, and taking the average grain of sand at around .23mm so that there are about 2300 lined up in one meter, cube that, using round numbers, and obtain 10 billion grains (10^10) per cubic meter. Imagine a beach 10m wide, 10m deep or any equivalent laying down of the sand (100 cubic meters per linear meter).

The length of the beach to have one grain of sand for each star would then be 10^11 meters or 100 million (10^8) kilometers.

Hence the not unreasonable concept that all the beaches and deserts of the world might approach sufficient volume to justify the old idea that if we bend down and pick up one reasonably-sized grain of sand, out of all on this planet, that's how our sun and solar system fit into the overall scheme of things.

« Last Edit: 29/06/2016 02:20:12 by Alan McDougall »

#### IAMREALITY

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##### Re: Can one estimate how many stars there are in the universe?
« Reply #3 on: 29/06/2016 07:03:24 »
Can one estimate how many stars there are in the universe?

Give it a go

Alan
There are 100-500 billion stars in our galaxy, which is considered average,  and 200-500 billion galaxies. So feel free to do the math.

Ps: you really love quora huh...

#### The Naked Scientists Forum

##### Re: Can one estimate how many stars there are in the universe?
« Reply #3 on: 29/06/2016 07:03:24 »