[Bairdh]

Where can I find information to read and learn about this new comet coming near us?
Where can I find out information on how astronomers figured out how many stars there are ? I not sure how they can know they are correct and this has biblical implications

[Capuchin]

Hi Bairdh

I did write a lengthy answer about the number of stars in the universe, but I managed to lose it, so I'm going to write a shorter reply.

To start, here is the comet that reached perihelion yesterday (closest point to the sun):
C/2006 P1 (McNaught)

As for the number of stars, we don't really know but we keep having stabs at it. It's very similar to counting the number of grains of sand on a beach. You don't count each grain, you have to take an estimate.

Luckily the estimate of the number of stars can be applied to theory and numbers that we should be able to observe come out of it, but most things in astrophysics have a large degree of error in them, just by the nature of what you are measuring.

For the number of stars in this universe, an error of +- 50% wouldn't be surprising. Things like dark matter confuse things a lot.

I hope this answers your question slightly. If you want to go into more detail just ask :)

[Nosnosna]

Estimates are much higher than billions... There are a few hundred billion stars just in our galaxy, and there are a lot of galaxies out there... reasonable estimates on the number of galaxies is on the order of 100 billion. Galaxy sizes vary widely, and there are stray stars out there that don't belong to any galaxy (though these are in the vast minority)

Information gleaned from here:

What is a galaxy? How many stars in a galaxy? How many stars/galaxies in the Universe? : Astronomy & time FAQs : Astronomy : Learning : National Maritime Museum

[Capuchin]

I think a first order estimate for number of stars in the universe would be about 10^24, that's something like 10^12 stars in each of 10^12 galaxies.

so that's 1,000,000,000,000,000 billion, or a million billion billion.

Of course, as mentionned before, the amount of error in this kind of measurement is phenomenal.

Keep in mind that's just an estimate for our universe, it could well be that there are other universes, and that would mean even more stars (maybe?). We just don't know.

[Capuchin]

I think maybe your 23 billion came from the current estimate of the age of the universe, which is 13.7 billion years. :)

[Starman]

I don't want to rain on anyone's parade but in respect to the unseen universe this kind of calculation is meaningless. Like looking at an animal's arse and based on that calculating how many hairs grow in its noes.

[Capuchin]

The best estimates point to a number of the order 7x10^22 stars in the observable universe, as starman says, there is no way to know anything past the observable sphere around the Earth, which is roughly 46.5 light years in any direction, at least until we get better techniques to be able to isolate how fast objects are moving about the centre of the universe (if ever).

We just don't know how big the universe is. Although I disagree with his analogy a little :)

But one thing is sure, that it's much bigger than the 23 billion you asked about in your rep

[saturday]

You can try nasa.com