What determines how many stars are visible?
The visibility of the stars in the night sky depends on the evenings weather conditions. More clouds = less visible stars.
There are many more people on earth than there are stars in the sky that are visible to the naked eye, even if you include all the stars that are ever visible from any spot on earth and not just the ones that you can see. However, if you include all the stars that we know about that are not visible to the naked eye, there are many more stars, by many orders of magnitude…
Values change, but.... With the naked eye about 133 stars are visible within 50 light years. With a telescope the value increases to about 2,000 stars. These values are only for visible stars, there is a high probability that there are brown dwarfs and cooler red dwarfs that have not yet been detected.
Just in our galaxy - the Milky Way - there are several hundred billion stars. In the visible Universe, there are hundreds of billions of galaxies. It is not currently known how far the Universe extends, beyond the visible limits. A rough estimate, then, would be that there are 1011 x 1011 = 1022 stars (a one with 22 zeroes, that is), just in the visible Universe - the part that our instruments can reach…
Explain why stars appear to move across the sky each night why are some stars only visible doing certain seasons?
Stars with titanium oxide only visible in cool burning stars because their structures, molecules can absorb photons at many wave lengths , producing numerous, closely spaced spectral lines that blend together to form bands. These bands form only in the coolest stars, this is because the molecules are not subjected to violent collisions.