Further on the the various compasses we navigate by:
Look up at the sky on a clear, moonless night, and you can make out the broad, hazy band of the Milky Way. For the longest time, observers were unsure what the milkiness was. Celestial clouds? Tiny stars? The “fiery exhalation” of large, sublunar stars, as Aristotle proposed? In 1610, using a telescope (a recent invention), Galileo revealed that the haze is made up of individual, barely visible stars; they are faint only because they are so distant. So continued the hard process of putting us in our proper cosmic place—an orientation that only gets more disorienting with each new scientific discovery.Today we know that the Milky Way is a galaxy a hundred thousand light-years wide and that it contains more than two hundred billion stars, including our sun. Our galaxy is shaped like a flat, spiraling disk, with a bulge at the center where the density of stars is greatest (there’s a black hole in there, too); we live more than halfway out, on one of the spiral arms. When you view the Milky Way, you are gazing through the plane of this disk and at the universe around and beyond—which, astronomers report, is imponderably vast and contains billions of other galaxies. Are there other sentient beings out there? Who knows. On Earth, at least, humans suppose that we alone seek out the sweep of our own galaxy. But we’re wrong. Late last week, in a paper in Current Biology, Marie Dacke, a biologist at Lund University, in Sweden, and her colleagues revealed that at least one other species takes guidance from the Milky Way: the dung beetle.
“People find them a bit revolting,” Eric Warrant, a biologist at Lund and one of the paper’s authors, said over the phone. “But they’re fascinating, and they’re the cutest animals you can imagine. When you’re holding one in your hand, they’re quite sweet.
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