spectra
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What the Heck is a Quasar?
I’ll give you a hint: this is not an image of a quasar. This image is from a first-season Star Trek: The Original Series episode, “The Galileo Seven” — the original footage, before it was remastered (and before astronomers had…
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What are Seyfert Galaxies?
Meet NGC 1566, an intermediate spiral galaxy in the constellation Fornax. To the human eye, this galaxy looks almost like any other spiral: It has a central nucleus and spiral arms, and it’s full of gas and dust. As an…
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What is the Hubble Law?
Last week, I teased you with the idea that it’s actually easy to estimate distances to galaxies. I do mean estimate — and distance indicators are still important. The Hubble Law is named for Edwin Hubble, the astronomer who was…
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Unique Neutron Stars
Neutron stars — the compact remains of massive stars that have gone supernova — are some of the most extreme objects in the universe, narrowly beaten by black holes (and, as we’ll talk about in future posts, active galaxies and…
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Binary Neutron Stars
Way back when we spent a number of posts surveying the stars, we covered binary systems. These are star systems that contain multiple stars. Imagine if our sun had a companion, and two stars rose and set in our sky…
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What Exactly are Supernovae?
This is one topic I bet you guys have been looking forward to since I first started posting about stellar evolution. Well, I won’t disappoint you! In my last post, we covered how a massive star gets to the point…
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What are Planetary Nebulae?
Meet the planetary nebula, one of the universe’s most gorgeous phenomena. If you’ve ever looked through a telescope, you may have seen one of these before. Through a small telescope, one might look like a little planet — hence the…
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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
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 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…
