2. Galaxies Forming

How do galaxies get their shape?  How was the Milky Way formed? 

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A century ago, we didn't know if there were two galaxies in the entire universe. Now we know there are over 1 trillion galaxies. What is the creativity that brought forth a trillion galaxies?

The Milky Way is a galaxy with huge spiral arms. When we first began to discovery galaxies we thought maybe these spiral arms were composed of physical matter, but actually it's much more interesting. The arms are actually waves that are passing through the galaxy. They are called density waves.  And as they pass through clouds of hydrogen and helium, they ignite star birth.

That's the way to picture the Milky Way Galaxy. Not such much as a thing, but rather as an activity. It's an ongoing activity of bring forth stars. We live in the midst of this intense creativity.

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What happened to expand our knowledge of the size and scale of the universe and its galaxies?

Around the 1900s, people started being able to measure distances to galaxies, like the Andromeda Galaxy and found out (the modern distance) is that it is about 2.5 million light years away. And that was just the beginning, wading out into the surf, of now being able to measure the distance of galaxies that are over 10 billion light years away.

Learn more about how galaxies are formed in the below podcast, or enroll in our FREE online course, created with Yale University.