When Is the Earth Nearest the Sun?
The Earth is nearest to the Sun on about the second or third day in January. The distance varies because the Earth spins round the Sun in an
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Distance
What Is a Mirage?
Mirages are optical illusions produced by extraordinary atmospheric conditions. They can be non-existent sheets of water or similar visions,
Who Sent the First Radio Message?
Guglielmo Marconi is usually credited with sending the first radio message. Marconi was born in Bologna, Italy, in 1874 to an Italian father
How Far Can You See?
How far the human eye can see depends on how many particles of light, or photons, a distant object emits. The farthest object visible with t
What Is Radar?
Radar, or radiolocation, as it was called in the early days, is the use of radio waves to find the whereabouts of aircraft or ships. Electro