The Milky Way galaxy is a giant star-city. Our Sun is one star in the
city, and there are many, many others, our neighbors. Our Galaxy
looks like a pinwheel - it is a
spiral galaxy. There are spiral arms and a bright central part.
The Sun is far from the center of the Galaxy. The Sun is going around
the center of the Galaxy, and it takes the Earth with it!
In our Galaxy, there are some old stars and some young ones. While
the Sun is old compared to you, it is young compared to the Galaxy.
Look at where the Sun is in our Galaxy. There are many more stars in
the center part than in the spiral arms where the Sun is. Can you
imagine what the sky might look like if our Sun, and the Earth, lived
near the center of the Galaxy, our star-city?
A galaxy like the Milky Way as viewed from the top, and the
actual Milky Way as viewed in the infrared
Click on top image for diagram (276K JPEG)
Click on bottom image for diagram (204K JPEG) European Southern Observatory & NASA COBE Project
Like other spiral galaxies, the Milky Way has a bulge, a disk, and a
halo. Although all are parts of the same galaxy, each contains
different objects. The halo and central bulge contain old stars and
the disk is filled with gas, dust, and young stars. Our Sun is itself
a fairly young star at only 5 billion years old. The Milky Way galaxy
is at least 5 billion years older than that.
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