I was once told that there is a grain of sand for every star in the sky, how likely is this?

Question

I was once told that there is a grain of sand for every star in the sky, how likely is this?

Answer 1

Stolen from: http://www.esa.int/esaSC/SEM75BS1VED_ind...

"For the Universe, the galaxies are our small representative volumes, and there are something like 10^11 to 10^12 stars in our galaxy, and there are perhaps something like 10^11 or 10^12 galaxies.

With this simple calculation you get something like 10^22 to 10^24 stars in the Universe. This is only a rough number, as obviously not all galaxies are the same, just like on a beach the depth of sand will not be the same in different places. "

Here: http://visindavefur.hi.is/svar.asp?id=48...

They get a surpisingly similar answer to the number of grains of sand, but only with a long list of assumptions.

Answer 2

Although no one is actually counting grains of sand or stars, the estimates are that there are probably more stars than grains of sand.  

Answer 3

It is, and shouldn't be, a constant source of amazement to me the things people are told, and what they choose to believe. I suppose that says something about my own intelligence; You would think by now I would have accepted the gulibility of the human race and the capacity of people to believe something without either proof or analysis. The answer is no. It's impossible for their to be a grain of anything in a star. Taking our sun as an example, (which, by the way, and much to the disappointment of those that think there is something special about the human race), it is a mediocre star much like the majority of stars. The surface temperature is ~12,000 degrees fahrenheit. At that temperature, sand, which is silicon dioxide,would be completely vaporized.....so is everything else. No chemical compound exists on any star. As an example of what I'm saying, consider the first nuclear detonation ever to take place. I was done on a steel tower in the desert of Nevada, Deserts are mostly sand. After the detonation, not only was the tower vaporized, but much of the sand in the immediate area was also turned into a gas. The part that wasn't was fused into glass.

By the way, and not really related to your question, but something to consider, the first nuclear bombs dropped on Japan, were likened to bringing a piece of the sun the size of a silver dollar to ~3000 ft. for ~ one millionth of a second!

Answer 4

seriously c'mon theres way more sand I'm willing to bet that there is a googleplex of grains of sand

Answer 5

I don't know how likely that is, but it makes you think, there must be trillions of grains of sand on just one beach, now imagine all the beaches on this earth.

Answer 6

As a very rough estimate, it is a good comparison.

Depends who does the counting (of stars and of sand), given that in both cases, we are talking about estimates.  No one has physically counted individual stars nor individual grains of sand.

It also depends what you call a star (do you include brown dwarfs?) and what you call a grain of sand.

Answer 7

To answer one of the comments.  There isn't a googlplex of anything in the universe, not even particles of dust, that's how large a number a googleplex is.

As for Stars vs. sand...

Obviously nobody could count all the sand grains, but I could do an order of magnitude calculation. Of course, sand comes in a variety of sizes. One standard definition is that medium sand is 0.25 to 0.5 millimeters in diameter, and fine sand is 0.25 to 0.125 millimeters. I chose, arbitrarily, to consider sand grains of 0.25 millimeters as an average. To further simplify matters I considered that each sand grain is a perfect cube, which allows for efficient packing.

Now all I had left to do was determine the volume of all the Earth's beaches! Simple, right?

Whoa, not really! First off, the best estimate I could find is that there are about a million and a half kilometers of shorelines on Earth. Not all of them have beaches per se, and some that do, have only very short beaches. Rather than stack the deck against the stars, I estimated that all the Earth's shorelines had a beach 50 meters back from the water. On the average, this may be an exaggeration. Next, how deep do you consider the beach to be? What is the definition? Who knows? A meter is about as deep as any summer beachcomber would ever dig, so I finally decided on that figure as the depth.

So, what is the number of sand grains, 0.25 millimeters cubed, that will fit in 1.5 million kilometers of beach, 50 meters broad and a meter deep? You can do the math yourself, or just accept my answer:

    4.8 x 1021

    That's 4,800,000,000,000,000,000,000! (Not even close to a google plex which has 100 digits)

Thus there is likely to be something less than 5 thousand billion billion grains of sand on the Earth's beaches!

OK, this must be far more than all the stars in the sky, right? Let's see.

Until recently, the total number of galaxies in the Universe was estimated to be about 10 billion. However, the Hubble Space Telescope has provided a much clearer view of the Cosmos, and today's estimate is that there are 50 billion galaxies. Generally speaking, our Milky Way can be considered fairly average with the mass equivalent to 100 billion stars. There certainly can be some argument here that not all of a galaxy's mass is in the form of stars. There may be super-massive black holes in their cores, as well as other unseen matter. Nevertheless I think it is legitimate to consider the Milky Way our yardstick here.

So 50 billion galaxies all roughly equivalent to the Milky Way (100 billion stars) amount to how many stars altogether?

    5 X 1021

That's still slightly more than all the grains of sand on Earth's beaches (even considering my rather generous assessment of shoreline fill). How many more? Oh, about 200 billion billion more stars than grains of sand. But of course, this is just an estimate. Still the old cliché seems vindicated.  

Answer 8

Well, I don't know.. Obviously there are billions of stars in the sky.. but I'm pretty sure there's a lot more sand. On one beach alone there are billions, even more, and then there are deserts... Yeah, Im pretty sure theres much more sand.

Answer 9

The saying goes, there are more stars in the universe than individual grains of sand on every beach on the planet Earth.  There are actually about 10 times more stars than grains of sand on every beach.  When you think that in our one galaxy there are between 100 billion and 300 billion stars and add to that there are 200 billion other galaxies in the universe, it should start making sense.  Some galaxies have 10's of billions of stars but most have 100's of billions and some have trillions of individual stars in each galaxy.