number of stars in all of known and possibly unknown universes?

Question

is it even remotely possible that thre are more stars then there are grains of sand on all the beaches of our world. I have heard that it is true, and the average star is approx. 1000 times larger then our sun.

Answer 1

Astronomers at the Australian National University have come up with a guestimate of 70 sextillion stars in the observable universe (7 x 10^22).

The comparison with grains of sand on earth's beaches comes from the astronomer Carl Sagan. I dont think he included the Sahara Desert, the Gobi Desert and other arid inland sandy areas in his calculations.

78% of stars are red dwarfs and they are smaller than our sun. Two of the nearest four stars are red dwarfs: Proxima Centauri and Barnard's Star. So I doubt the average star is 1000 times larger than out sun. But there are certainly larger stars than our sun:

Here is a list of the 16 largest known stars:
Star name Solar diameter
(Sun = 1)
VV Cephei 1900
V354 Cephei 1520
KW Sagitarii 1460
KY Cygni 1420
Mu Cephei (Herschel's "Garnet Star") 1420
La Superba (Y Canum Venaticorum) 1100
S Doradus 1000
V509 Cassiopeiae 910
R Leonis 900
R Doradus 830
V838 Monocerotis 800
V382 Carinae 747
Rho Cassiopeiae 738
Mira A (Omicron Ceti) 700
Antares (Alpha Scorpii) 700
Betelgeuse (Alpha Orionis) 650

But as you can see, only 7 of them are 1000 larger in diameter than our Sun.

Of course, stars that are a mere 10 times larger in diamater than our Sun will be 1000 times its volume as the volume of a sphere is 4/3 x pi x radius^3. So it depends what you mean by 1000 times the size. 1000 times the diameter or 1000 times the volume.

Answer 2

Do the math.

It is estimated that there are 100 billion stars in the Milky Way galaxy. If each star were a 1mm grain of sand, that would be 100 cubic meters of sand, about 10 dump trucks full. There are an estimated 100 billion galaxies in the known universe, so that would be a trillion dump trucks full of sand. If it were spread evenly over the entire Earth, including the sea floor, it would be a layer 2mm deep. Not very deep, but covering the whole world. Is that more than all the sand on Earth? I don't know, but I suppose it could be.

Answer 3

There is approximately 10^10 stars in our solar system. So that's 10000000000 stars. There are then (probably) 10^10 galaxies making an approximate total of 10^20 = 100000000000000000000 stars.

The volume of sand on the Earth is going to be of the order of 6000000^2 (approx surface area of Earth) x 5 (let's say a depth of 5 metres) which is about 10^14 cubic metres of sand. The volume of a grain of sand is about 10^-10 cubic metres which leaves us with about 10^24 grains of sand. You could give or take a few orders of magnitude given that the whole surface of Earth is not covered in sand, and variations in depth.

So in short, it'd be a close call!

Answer 4

3

Answer 5

1) The number of galaxies. An estimated 50 billion galaxies are visible with modern telescopes and the total number in the universe must surely exceed this number by a huge factor, but we will be conservative and simply double it. That's 100,000,000,000 galaxies in the universe.

2) The number of stars in an average galaxy. As many as hundreds of billions in each galaxy.

Lets call it just 100 billion.

That's 100,000,000,000 stars per galaxy.

3)The number of stars in the universe.

So the total number of stars in the universe is roughly 100 billion x 100 billion.

That's 10,000,000,000,000,000,000,000 stars, 10 thousand, billion, billion. Properly known as 10 sextillion. And that's a very conservative estimate.

now there may be infinite universes. so thats 10,000,000,000,000,000,000,000 x infinity

Answer 6

Yes that is true. The universe is far larger than we can begin to image. The Earth is quite small compared to the universe so the amount of sand is small compared to the stars.

Answer 7

I think I read it was six billion trillion.