Re: Why do stars appear smaller than the sun?

Hi Michelle,
The answer to your question is that all the other stars except for our
sun are very, very far away. I mean this in relative terms, because after all,
the sun is on average about 93 million miles away (~ 150 million km). This
is considered "close" by astronomers. If you  have ever been near the
top of a  tall building, or looked out the window of an airplane, you've 
probably seen that people and cars look tiny from there. The same is true
if you look at a ship far out on the ocean. It looks so small, even though you 
know it hasn't really shrunk, it just looks that way because of the 
great distance. 

To illustrate the "LARGE" distance to other stars, consider this. The
distances are normally measured in something called a "light year". This is a 
distance equal to how far a beam of light will travel in a year. Now light 
travels at ~ 300,000 km per second (it is the fastest thing known).  In terms of 
the speed of light, the sun is about 8 light minutes away. In other words, 
it takes light from the surface of the sun 8 minutes to get to earth (even 
though it travels at that enormous speed). The nearest star is alpha centauri 
(visible in the southern hemisphere, but not here in the US where I'm from, so 
I've never actually seen it myself). Alpha centauri is 4.3 light years away from 
earth. That works out to 4 x 10 ^13 km ( = 40,000,000,000,000 km = 40 trillion 
km). And that's the closest one!

Another famous star called Betelgeuse (in the constellation of Orion)
is 650 light years away. Betelgeuse has a radius of about 1000 times larger
than our sun. In terms of our solar system, its surface would reach all the
way out to past the orbit of mars, and all the inner planets (mercury, venus,
eart, and mars) would be INSIDE Betelgeuse's surface. But even though it 
is much larger than the sun, it is so far away that it just looks like a point 
of light to us, just like all the other stars.
* * *Note added by MadSci Administrator:  Recently the disk of Betelgeuse has 
been "imaged" by the Hubble Space Telescope, but nobody has ever actually seen 
the star with just their eyes as anything other than as a point.* * *


If your school or library has a computer connected to the internet, there is a 
website that contains questions and answers about astronomy that you
might want to explore.

   Astronomy