Look up on a clear night and the most obvious feature of the universe is not the stars. It is the darkness between them. That darkness seems perfectly ordinary, yet for centuries it posed a surprisingly deep problem. If space contains an en...
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Somewhere on Earth, while you read this sentence, babies are being born and people are dying. Others are crossing national borders, changing the population of one country without changing th...
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A dog stops halfway through a walk, lowers its head and begins grazing with the concentration of a miniature cow. For many owners, what happens next seems obvious: the dog must have an upset...
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It is one of those questions that sounds almost too simple to deserve a scientific explanation. Look up on a clear afternoon and the sky is blue. Yet that familiar color is the visible resul...
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Imagine putting the entire Solar System on a cosmic scale: the eight planets, every known moon, the asteroids, comets, dwarf planets, dust and the enormous Sun. The result would be absurdly...
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At this moment, Earth is moving in several different ways at once. It spins on its axis, circles the Sun at roughly 30 kilometers per second, and accompanies the entire Solar System on a vas...
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Space is a vacuum, so an astronaut cannot simply lift a visor and take a sniff. Yet crews returning from spacewalks have repeatedly described something remarkably close to a smell of space:...
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In the Chihuahuan Desert of northern Mexico, where Durango, Chihuahua and Coahuila approach one another across an immense dry basin, a patch of landscape has acquired one of the strangest re...
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For generations, chemistry books could place bismuth near the end of the periodic table's stable territory. Its naturally occurring isotope, bismuth-209, showed no detectable radioactive dec...
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In 1929, while scholars were cataloguing manuscripts in Istanbul's Topkapı Palace, they encountered a fragment of an extraordinary world map. Painted in vivid colors on parchment traditional...
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