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Sunday, 17 January 2016

Light

Until the 17th century, light was thought to travel instantaneously. Galileo, in 1638, was the first to show otherwise and try to measure its speed.

The people of Perth in Australia all turned their lights on at the same time on February 20, 1962 to greet astronaut John Glenn who was orbiting above them in Friendship 7.

Light's speed in a vacuum is about 186,282 miles a second.

Rays of light shine through metal patterns into a railway station

Light doesn't necessarily travel at the speed of light. When travelling through glass its speed slows down to about 124,000 miles a second.

In 1999, Harvard physicist Lene Hau was able to slow down light to 38 miles per hour.

It takes 8 minutes for light to travel from the sun to the earth.

Sunlight can reach a depth of 80 metres in the ocean.

Around 1670 Sir Isaac Newton identified five colors in the light spectrum: red, yellow, green, blue and violet. He added orange and indigo later.

There is no red light 30 feet underwater, so blood appears green.

When light is refracted in raindrops, a rainbow is made. The raindrop acts like a prism and refracts the light until we can see the colors of the spectrum.


Some creatures produce their own lights - bioluminescence. The Brazilian railroad worm has a red light on its head and green ones on its side.

There is a Right to Light law in England. The owner of a building with windows that have received natural daylight for 20 years or more is entitled to forbid any construction or other obstruction that would deprive him or her of that illumination.

Source Daily Express

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