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Geologists Sing a Happy Lidar Day Song

Washington State geologists working for the Department of Natural Resources threw themselves a party the other day. The earth scientists were celebrating what they called "Lidar"  day, a somewhat nerdy affair. Lidar is one of those acronyms favored by government agencies - It means light detection and ranging - a combination of laser and radar.

The technology isn't all that new. It's been around ever since the Apollo missions to the moon when astronauts set up reflectors on the moon so that earth-bound lasers could be bounced off them to precisely measure distances.

Since then, geologists have figured out how to mount the combination equipment  - lasers and radars - on airplanes to take millions of measurements over the earth surfaces.

Lidar is now used commonly to identify geologic features underneath vegetated regions, because it can easily and quickly penetrate dense forest canopy to show the ground surface underneath. Foresters use it to gauge the height and volume of timber, And new vehicle gee-whiz collision avoidance technology uses a form of lidar.

By the way - lidar has confirmed a possibly unpleasant astronomical fact. Our moon is moving out of Earth's neighborhood. It's pulling away at about 3-point-8 centimeters a year.

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