What is the Milky Way, and from what vantage point are we viewing it?

On Mon, 20 Mar 2000 you wrote:

> The thick band of stars is often referred to as the "Milky Way". I
> understand that we are located in the Milky Way galaxy. What specifically am
> I looking at when I see what is commonly referred to as the "milky way" and
> from what vantage point am I seeing it. thanks for you help.

A galaxy is a collection of stars that all orbit around each other. There
are two types of galaxies - elliptical galaxies, which are shaped like
footballs, hamburgers, and basketballs, and spiral galaxies, which are
flat like a frisbee and have arms.

Our Milky way galaxy is a spiral galaxy. Our sun, like the majority of
stars in the Milky Way, circles around in the disk. Imagine the Milky Way
to be shaped like a phonograph record. Our sun follows an orbit like the
groove on the record (except that we don't spiral in or out). So, you can
imagine that if we lived in the groove of a record, we would see a thick
black band making a circle across our sky (the record itself), and clear
skies above and below (looking out and away from the record). Our galaxy
is very similar, except the Milky Way is made out of stars, not vinyl.
The thick band that makes up what we call the Milky Way is the disk of our
galaxy, as seen from the inside. It appears to form a complete circle
around us, although we don't live at the center. The stars we see in the
sky that are outside of the band of the Milky Way still belong to the disk
of the galaxy; they are just very nearby. It's like seeing a forest of
trees on the horizon - the limbs of the trees appear to be close to the
ground. But if you walk into the forest, the tree limbs appear overhead,
too.

I hope this makes sense. Try to imagine what it looks like if we were to
live in a disk, and you should get the general idea.

Oh, you may also notice that the Milky Way in the summer sky is much
brighter then the Milky Way in the winter. This is because we are looking
towards the center of the galaxy in the summer, and toward the outer edge
in the winter. We live 2/3 of the way to the outer edge, so there are
more stars closer to the center then there are further out.

Thanks for writing!

Sincerely,
Kurtis Williams

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