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Satellites and laser beams is correct. Scientists at observatories on
two different continents, such as North America and Europe, use a space
satellite mirror to reflect laser beams sent between the observatories. By
knowing the fixed location of the satellite, scientists can calculate the laser
beam's travel time to each observatory, and triangulate to arrive at the
distance between the observatories. They can then compare the most recent
distance to the distance from a year before, and calculate how far the
continents have moved during that time.
This technique reveals that North America and Europe move apart 20mm (0.8 in) a
year. If you lived to be 100, how much farther apart would they be than they
are now?
OK. Does this make sense to you? If not, why? How would you go about finding
more information to use to determine whether you think this could work? And
what other evidence might convince you that continental plates move?
Want to know some other ways satellites way out in space can help make accurate
measurements? Check out Desert Finds and Remote Sensing to see.
(back to measurement page)
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