hydrogen
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A Cosmological Timeline
We started covering cosmology way back in April. And since then, we’ve explored quite a bit — in fact, the grandest story the universe has to offer. We’ve followed the universe from the first fractions of a second after the…
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The First Nucleosynthesis
One minute after the Big Bang, all the protons, neutrons, and electrons that would ever exist had been produced. There were no atomic nuclei, though. No atoms. No materials as you and I know it — like wood, metal, or…
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The Composition of the Milky Way
What is our home galaxy made up of? In the broadest sense, it’s made up of stars, clouds of dust and gas, and the mysterious dark matter. We could also get a little more detailed. We could say that it…
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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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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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The Proton-Proton Chain
Take a wild guess: how much energy do you think the sun generates? Think about it. It definitely generates enough energy to power a world. Humans depend on the photosynthesis of plants, which converts sunlight into energy. And that’s not…
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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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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.…
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Types of Atoms
Does this look familiar? It might, or it might not. If it does, you might recognize it as the periodic table of the elements — more often known as simply the “periodic table.” It’s an ingenious way to organize elements…
