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Q: More stars than sand particles? ( Answered 4 out of 5 stars,   11 Comments )
Subject: More stars than sand particles?
Category: Science > Astronomy
Asked by: dimator-ga
List Price: $3.50
Posted: 02 Jul 2005 02:05 PDT
Expires: 01 Aug 2005 02:05 PDT
Question ID: 539329
I remember hearing or reading that there are more stars in the
universe than there are particles of sand on Earth.  I was at the
beach the other day, and there seemed to be a *LOT* of sand particles
on the beach, not even considering the rest of the planet.  Is such a
statement accurate?  How can such an estimate be made logically?

I want estimates of how many sand particles there are in one cubic
inch, foot, mile, ... planet Earth, and also, the latest, most
scientifically valid estimates of how many stars are in the universe.
Subject: Re: More stars than sand particles?
Answered By: richard-ga on 03 Jul 2005 21:10 PDT
Rated:4 out of 5 stars
Hello and thank you for your question.

"So how many grains of sand are there in the world? You could start
off by trying to guess how many grains of sand there are in a spoon of
sand. Use a magnifying glass to count how many grains fit in a small
section. Then, count how many of those sections fit in your spoon.
Multiply the two numbers together to get an estimate.
"Using this same principle, plus some additional information,
mathematicians at the University of Hawaii tried to guess how many
grains of sand are on the world's beaches. They came up with
7,500,000,000,000,000,000, or seven quintillion five quadrillion
grains of sand."
How many grains of sand are in the world?

The calculation is detailed here:

That number is 7.5 x 10^18 or 7.5 billion billion.

How many stars, galaxies, clusters, QSO's etc. in the Universe?
"To get the total stellar population in the Milky Way [that is, in our
galaxy alone], we must take the number of luminous stars that we can
see at large distances and assume that we know how many fainter stars
go along with them. Recent numbers give about 400,000,000,000 (400
billion) stars, but a 50% error either way is quite plausible."

So in our galaxy alone, there might be between 2 x 10^11 and 6 x 10^11 stars

How many galaxies in the Universe?
"the Hubble telescope is capable of detecting about 80 billion
galaxies (although not all of these within the foreseeable future!). 
In fact, there must be many more than this, even within the observable
Universe, since the most
common kind of galaxy in our own neighborhood is the faint dwarfs
which are difficult enough to see nearby, much less at large
cosmological distances. For example, in our own local group, there are
3 or 4 giant galaxies which would be detectable at a billion
light-years or more (Andromeda, the Milky Way, the Pinwheel in
Triangulum, and maybe the Large Magellanic Cloud). However, there are
at least another 20 faint members, which would be difficult to find at
100 million light-years, much less the billions of light years to
which the brightest galaxies can be seen."

So the lower end estimate for the number of galaxies is 8 x 10^10

If we accept even the lower end of these Hubble figures, and if our
Milky Way has a typical number of stars in it, that puts the number of
stars in the universe to be at least
(2 x 10^11) x (8 x 10^10) = 16 x 10^ 21

So if we round the number of sand grains to, say, 10^20
and round the number of stars to, say 10^22
then there are at least 100 stars in the universe for every grain of sand on earth.

As you say, that's a *LOT*

Search terms used
beach sand particles cubic
"number of stars in the universe

Thanks again for your interesting question
dimator-ga rated this answer:4 out of 5 stars
What a great response, I'm glad I brought my question here!

Subject: Re: More stars than sand particles?
From: iang-ga on 03 Jul 2005 01:02 PDT
Unfortunately, noone knows how how many stars or sand grains there
are. If you search for grains, sand, Earth, stars & universe you'll
find a lot of suggestions though.  Most of them are good at explaining
the assumptions they've made in counting grains of sand, but state the
number of stars as a matter of fact. In reality there are a lot of
assumptions made in counting stars, too - these links might be

Ian G.
Subject: Re: More stars than sand particles?
From: sparkmencer-ga on 03 Jul 2005 14:02 PDT
There are more stars than grains of sand on the earth.  With sand,
there is a definite number of particles.  The cosmos are
infinite...the further you look, the more will be found, forever.
Subject: Re: More stars than sand particles?
From: singularity360cubed-ga on 03 Jul 2005 22:39 PDT
I would refer you to the Deep Field Image, that the Hubble came up
with.  You will soon find that the count of stars has to be of greater
number, given the small patch that the Deep Field Image represents,
once it is factored...!

Subject: Re: More stars than sand particles?
From: pinkfreud-ga on 04 Jul 2005 11:43 PDT
What a great answer, Richard! 

I'd have given it five stars. Or 500 grains of sand. :-D
Subject: Re: More stars than sand particles?
From: dprk007-ga on 04 Jul 2005 20:22 PDT
Modern theories of cosmology contend that our Universe is FINITE both in 
size, when it was born and total number of GALAXIES and STARS. The
researcher has done a calculaton to indicate a lower limit on the
number of stars. However there would be an actual total number of
stars (i.e. which is not infinite)
Subject: Re: More stars than sand particles?
From: pugwashjw-ga on 04 Jul 2005 20:47 PDT
Genesis 1;16-18 " And God proceeded to make the two great luminaries,
the greater luminary for dominating the day and the lesser luminary
for dominating the night, AND ALSO THE STARS. 17. Thus God put them in
the expanse of the heavens to shine upon the earth. 18. And to
dominate by day and by night and to make a division between the light
and the darkness. Then God saw that it was good".
The scripture implies that Earth is a very special place. More
important even than the stars in the universe. The words 'and also the
stars' seem to relegate them to a lesser importance. Maybe we have to
learn to look after this place before we are allowed out THERE.
Subject: Re: More stars than sand particles?
From: dprk007-ga on 07 Jul 2005 19:22 PDT
As I do not read the bible that much, I am a little bit unfamiliar 
with the biblical jargon.
So perhaps you can confirm what you have said can be interpeted thus in
pure layman's terms:

1. God Said Let there be a Planet earth and a planet earth appeared.

2. One or two days later God said let there be the sun and and a G type yellow
   dwarf appeared on the scene.

3. A couple of days later God said let there be stars and 10^22 stars appear
   (as per Richard-ga estimation) along with Planets , moons of planets, 
   asteriods, pulsars, quasars, galaxies,brown dwarfs, planetary nebula and 
   many other types of astronomical bodies which we may never have heard 
4. And then god said let there be man and a man appeared on October 23rd  
  4004 BC (was a pretty hectic week all round!!)

Subject: Re: More stars than sand particles?
From: dprk007-ga on 07 Jul 2005 19:25 PDT
oops regarding my point 4 I meant to say:
And then god said let there be man and a man appeared on October 23rd  
  4004 BC at nine o'clock !!.

Subject: Re: More stars than sand particles?
From: nemtudom-ga on 25 Jul 2005 04:25 PDT
7,500,000,000,000,000,000 is seven quintillion five *hundred* quadrillion.

It's interesting to note that ancient people, without telescopes,
somehow had the idea that the number of stars was so great as to be in
the same league with the grains of sand, e.g., "I will multiply thy
seed as the stars of the heaven, and as the sand which is upon the sea
shore" (Genesis 22:17).

It's interesting to note that most statements beginning "it's
interesting to note" are not interesting to note.
Subject: Re: More stars than sand particles?
From: noseallinit-ga on 10 Jan 2006 21:35 PST

Ask A Scientist©

Astronomy Archive

Stars or Sand

Question:  Are there more stars or are there more grains of sand?
m french

Answer:  Well, if every star came with a planet like earth that had billions of
sand grains, there would have to be more sand grains than stars! The number of
stars in our galaxy is around 100 billion or 10^11 in exponential notation. The
number of sand grains on earth is probably somewhere between 10^20 and
10^24. Th e number of sand
grains on earth is therefore much greater than the number of stars in our
galaxy. However, our galaxy is only one of about 100 billion in the visible
universe, and so the total number of stars we know about is around
10^22, which  is kind of in the same
ballpark as the number of grains of sand on earth.
Of course, those numbers are much bigger than we can count - I'm not sure
whether better estimates of both numbers would give more stars, or more sand
grains - there's a lot of both!
Subject: Re: More stars than sand particles?
From: richard-ga on 07 Jun 2006 07:31 PDT
According to this recent article,
the Andromeda galaxy has a trillion stars, that is, 10^12
So if that's the size of a typical galaxy, there are closer to 10^23
stars in the universe, or about 1,000 stars for each grain of sand.

By the way, if you recall Avogadro's number from chemistry (6 x
10^23), the number of stars in the universe neatly matches the number
of molecules in 22.4 liters (6 gallons) of uncompressed air or other
gas at standard temperature (0 celsius or 32 fahrenheit) and pressure
(1 atmosphere).


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