Spectroscopy
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What Makes a Star Blue?
Albireo is the distinctive double star in the head of the constellation Cygnus. You can find it yourself if you look for the Summer Triangle amid the dusty trail of the Milky Way across the night sky. The brighter, orange…
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Our Sun: The Chromosphere
This diagram is a tiny bit misleading. Here, it looks like the chromosphere is the visible surface of the sun, with the photosphere just below. Really, we never see the chromosphere. If you ever look through a solar telescope at…
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The Doppler Effect
Have you ever heard the ice cream truck? When I was little, I remember hearing the ice cream truck all the time. Just the sound of the opening notes of “Pop Goes the Weasel” were enough to propel me to…
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Star Stuff & Cecilia Payne
If this quote really is from Cecilia Payne, then she had the right idea — at least for a female astronomer in the 1920s. Women in science back then faced an uphill battle to get recognized for any discoveries they…
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The Balmer Thermometer
How hot would you say this star is? Take a wild guess. Well…sorry, but I’m going to stop you for a moment just to make sure we’re all using Kelvins. The Kelvin scale is like the Celsius scale, except water…
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The Atomic Spectrum
Astronomers know that if white light passes through a prism and is bent, it’s separated out into its component colors — the colors of the rainbow. Astronomers also know that when light interacts with atoms, the building blocks of the…
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Atoms and Radiation
Everything we know about space comes from radiation. Now wait just a moment here. That statement explains how astronomy is such a successful field of science — it’s based entirely on the information we can glean from radiation, after all.…

