During photosynthesis, plants emit light humans can’t see, but NASA can see that light from space - and they've even made maps of it!
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Optical illusions occur when what the eyes see conflicts with what the brain expects.
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The Earth's atmosphere weighs about 5.5 quadrillion tons.
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Oxygen, carbon, hydrogen and nitrogen make up 90% of the human body.
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The average temperature at 40,000 feet above sea level is -60 F.
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Iron weighs more after it rusts.
16
A single speck of dust is half way in size between a subatomic particle and the Earth.
15
The brain case [of Neanderthals] on the average was more than 13 percent larger than that of the average of modern man
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