The Milky Way

  • What Are Spiral Arms?

    What Are Spiral Arms?

    Probably the most spectacular feature of our Milky Way galaxy is its spiral arms. We can’t get a probe far enough out yet to take a galactic selfie, but astronomers are reasonably sure that we live in a spiral galaxy.…

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  • Exploring the Milky Way’s Spiral Arms

    Exploring the Milky Way’s Spiral Arms

    The Milky Way — our home galaxy — is a spiral galaxy, a classification I often describe as pinwheel-shaped. The main difference between a spiral galaxy’s shape and a pinwheel’s shape is that spiral galaxies, like the Milky Way, only…

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  • How Massive is the Milky Way?

    How Massive is the Milky Way?

    Over centuries of philosophy and research, through the times of the classical astronomers to Galileo’s observations of the Milky Way, humanity’s understanding of our universe has evolved from a simple model of the sun and planets to a vast wheel…

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  • Structure of the Milky Way

    Structure of the Milky Way

    In the vast expanse of the cosmos, the Milky Way Galaxy is our home. You’ve no doubt seen images of the Milky Way and similar galaxies elsewhere online. It’s a large, spiral galaxy, one of the most spectacular galactic shapes.…

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  • How Big is the Milky Way?

    How Big is the Milky Way?

    How big is our galaxy, anyway? And more than that — how do we know? Consider that we can’t really take a photo like this of our galaxy. We’re inside it, and space travel has not advanced to the point…

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  • Discovery of the Milky Way

    Discovery of the Milky Way

    Ever seen this before? It’s not a sight that most of the developed world gets to see — at least not all the time. Light pollution from major cities completely obscures this view. Even in the suburbs where I live,…

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