How many galaxies are in the universe?
There are about 2*10^11 galaxies in the universe, as the smart apples like to say.
That is, a 2 followed by eleven zeros, or 200 followed by 9 zeros, which is another way of putting it.
Or you could just write it out as 200,000,000,000, which is tedious, but probably a more familiar way of expressing it.
If you wanted to forego a strictly numeric expression, you could describe the number of galaxies in the universe as two hundred thousand million... but the simplest, most familiar way would be to just say or write two hundred billion. Two hundred billion galaxies. That's how many galaxies there are floating around out there in space.
Two hundred billion galaxies, yup. That's how many galaxies...
Throw all of that crap right out the window, because that's what we used to think. Because NOW we've discovered, very recently, like in the last couple of days, that there are many many many MANY more galaxies bouncing around out there than we ever, ever, ever EVER would have imagined... as in, somewhere around 2*10^12 galaxies, as the smart apples like to put it, hanging out in all of the vasty deeps.
2*10^12 galaxies. That is, a 2 followed by12 zeros. 2,000,000,000,000. You know. Two thousand billion, or two trillion.
We live in a universe which contains TWO TRILLION galaxies.
Your average galaxy contains about two hundred billion, or two hundred thousand million, or 200,000,000,000, or 2*10^11 stars.
Oh... and I just realized that I probably should've explained wallago about how scientific notation works and how to read it. It's about powers of ten, you know? Remember that from junior high?
Just in case you don't, it's like this:
10 to the first power is written 10^1
The ^ symbol signifies 1 as an exponent.
10 to the first power is 10^1
10 to the first power equals 10
10^1 = 10
10^2 is 10 to the second power
10^2 is the same as 10 squared.
10^2 means10 multiplied by 10
10*10 = 100
10^3 is 10 to the third power
10^3 is 10 cubed
10^3 = 10*10*10
10*10 = 100
100*10 = 1000
10^3 = 1000
And so on. Get it? So in order to write numbers in scientific notation that aren't limited to the strict powers of ten, you just multiply the power of ten by another number. So, if you wanted to write, say... 4000 in scientific notation, you'd write it like this:
In other words, the exponent of the power of ten is the number of zeros following the first integer.
Our own galaxy, The Milky Way, is a fairly average sized, barred spiral galaxy which contains around 200 billion stars. Since the Milky Way is pretty run-of-the-mill as far as galaxies go, then we can safely assume that the average galaxy in the universe probably contains about two hundred billion stars, more or less.
Now, multiply 2*10^11, or 200 billion, by 2*10^12, or 2 trillion. To do that, you just multiply the integers and add the exponents.
2(10^11) * 2(10^12)
4 with 23 zeros
So, just FYI. There are approximately two trillion galaxies in the universe, and four hundred sextillion stars. Approximately.
Galaxies = 2,000,000,000,000
Stars = 400,000,000,000,000,000,000,000