interstellar medium

  • What are Molecular Clouds?

    What are Molecular Clouds?

    Meet the Pillars of Creation, a photograph taken by the Hubble Telescope in 1995. These apparent “pillars” of dust and gas are what we call molecular clouds. And this region of clouds in space is aptly named: it’s where stars are…

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  • What is the Intercloud Medium?

    What is the Intercloud Medium?

    Stars are like headlights in a fog bank that’s impossibly thick in some places, and so thin as to be transparent in others. Sometimes, we get lucky enough for starlight to light up the fog. Other times, stars shine straight…

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  • What are Cool Clouds?

    What are Cool Clouds?

    Have you ever driven through fog? I’m going to guess, for the sake of this post, that you have. And if you haven’t…well, I think the image above should give you a pretty good idea of what it’s like. Low…

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  • Radiation from Interstellar Dust

    Radiation from Interstellar Dust

    Does this sight look familiar? If you’ve had the opportunity to observe the night sky from a dark place, far away from the light pollution of the city, on a clear night, you might have seen this before. It’s the…

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  • Interstellar Spectra

    Interstellar Spectra

    I often refer to what we call the interstellar medium as the galaxy’s “backstage,” and I do that for a reason: for the most part, we can’t see it. The backstage of any theater isn’t part of the show. You, as…

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  • Extinction and Reddening of Starlight

    Extinction and Reddening of Starlight

    Take a wild guess: What do you think this image is showing you? If you said it looks like a giant black hole in space, I don’t blame you. I also don’t blame you if you thought it looks like…

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  • What is a Nebula Made of?

    What is a Nebula Made of?

    What you see here is the Trifid Nebula, a vast cloud of gas and dust in space. In my last post, we explored why it looks the way it does. We discovered that the pink hues of emission nebulae are caused…

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  • What is a Nebula?

    What is a Nebula?

    What’s a nebula? Well…you’re looking at one. Okay, okay, I know. You want to know what that actually is. You want to know why it’s there. You want to know why there are colors in space…and why you’ve never noticed…

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