Balsa wood is classified as a hard wood!
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The Earth's atmosphere weighs about 5.5 quadrillion tons.
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It takes a photon 170,000 years to travel from the core of the Sun to the surface, but only 8 minutes to travel the rest of the way to Earth.
6
In 1999, Harvard physicist Lene Hau was able to slow down light to 17 meters per second and in 2001, was able to stop light completely.
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Only 12,000 years ago there was a species closely related to modern humans called Homo floresiensis that had been living on an Indonesian Island. They used fire and rather advanced tools, yet were only about 3 feet tall and weighed around 25kg.
15
A 'jiffy' is an actual unit of time for 1/100th of a second!
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One 75-watt bulb gives more light than three 25-watt bulbs.
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One cubic foot of gold weighs more than 1,200 pounds!
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