Research Rack: Did You Know?

• A person blinks once every five seconds. That means that most people's eyes are shut for nearly 30 minutes while they are awake each day.

• Red eye in pictures is caused when the light from the flash reflects off the choroid, blood vessels that nourish the retina. To avoid having eyes appear red in pictures, look slightly to the side of the camera.

• The idea of the light wave came from Christian Huygens, who proposed in the late 1600s that light acted like a wave instead of a stream of particles.

• In a vacuum, electromagnetic waves travel at the speed of light.

• The Space Shuttle moves at 18,000 mph and takes 90 minutes to orbit the Earth. During that time, the astronauts onboard the Shuttle witness one sunrise and one sunset. In a 24-hour period, that adds up to 16 sunrises and 16 sunsets.
  • The Sun sets in about 13 seconds -- from the time it "enters" the Earth's atmosphere until it is completely vanished behind the Earth.

• The word volcano comes Vulcan, the Roman god of fire.

• A volcanic eruption known as a Plinian can produce a large cloud of ash that may rise 48 km (30 miles) into the atmosphere.

• Aerial surveys using ice-penetrating radar have detected active volcanoes buried 1.6 km (1 mile) below the Antarctic ice sheets.

• Ben Franklin is thought to have made the first link between climate and volcanoes. For much of 1783/1784, Franklin observed a "dry fog" over Europe and exceptionally cool weather. Franklin thought that the weather change was related to the huge eruption of the Laki Volcano in Iceland.

• If you shrank Earth to the size of a basketball, by comparison its atmosphere would have roughly the thickness of a sheet of plastic wrap.

• In 1735, English meteorologist George Hadley suggested that winds are affected by the rotation of the Earth.

• Columbus used the Trade Winds in his voyages!

• Frequency is measured in units of cycles (waves) per second, or Hertz (Hz).
  • The frequency of visible light is referred to as color and ranges from 430 trillion Hz, seen as red, to 750 trillion Hz, seen as violet.