dark matter
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The Problem of Matter
At first glance, this is an ordinary image of a galaxy cluster: specifically, Abell 1689. If we look closer, though, we see that there’s something weird going on with the more distant, background galaxies in the image. Many of those…
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From the First Nuclei to First Light
When we talk about the first 30 minutes of time, we describe the universe expanding and cooling. As the universe cooled, the nuclear reactions that produced the first atomic nuclei slowed and stopped. But it was only relatively cool. The…
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Is Dark Matter Real?
Here we are, people — it’s finally time to talk about dark matter! I’ve teased this subject in my last few posts. We’ve discussed how the idea originated — with observations of the rotation of galaxies. We’ve touched on the…
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A Peek at Supermassive Black Holes
There are few things in the universe quite as exciting as black holes. They’re in all the movies — I even wrote a post a few years ago on what the movies get wrong about them! Though some movies, like…
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How Massive are Galaxies?
If you needed to measure the mass of, say, a brick — or some other Earthly object — you could just set it on a scale. (Yes, scales measure mass, not weight.) With galaxies, it’s not so easy! I don’t…
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The Milky Way Demystified
Alright, people…time to finish off our exploration of the Milky Way Galaxy, our home in the cosmos! For the past nine weeks, we’ve covered everything from how our galaxy was “discovered” to how it may have formed. But there’s so…
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Exploring the Milky Way’s Nucleus
Here is an edge-on illustration of our Milky Way Galaxy. (Keep in mind that the disk actually stretches quite a bit farther out from the budge than is apparent in this illustration. Proportionally, its full diameter makes its thickness less…
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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…
