 We
now interrupt this broadcast...
Radio waves normally travel in straight lines, but as scientists
experimented with early radio, they discovered a strange thing: sometimes
they picked up radio signals from transmitters beyond the horizon.
How could this be? Maybe, the British scientist Oliver Heaviside
suggested, the radio waves were reflecting off an electrically conducting
layer at the top of the atmosphere – the ionosphere.
Guglielmo
Marconi, the inventor of
radio, bounced the first
signals off the ionosphere
and across the Atlantic Ocean
in 1902. A few years later,
radio operators were doing
this regularly to reach sites
thousands of miles away.
Useful
as this is, depending on
the ionosphere has its problems.
Starting in the late 1920’s
Karl Jansky studied how magnetic
storms caused by the Sun
can wreak havoc with long-range
radio.
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