The Visitor Information Station at Mauna Kea, Hawaii, holds a nightly stargazing program. Per its website (
http://www.ifa.hawaii.edu/info/vis/stargazing.html ), �As soon as it�s dark enough, a star tour will be given. Using a
laser pointer, we will point out all the bright constellations and bright objects visible that night.�
The green laser beam was a few miles long and was clearly visible along its entire length. The astronomer wielded it effortlessly as a giant pointer. The skies were crystal clear and the stars were bright. From a 9,300 feet altitude, we could see Polaris to the North and the Southern Cross to the south.
The pen-sized laser used is sold in the gift shop for under $100. Its specifications are:
� 5 milliwatts (0.005 watts)
� Two AAA batteries
� 12,500 feet range
� 532 nanometer wavelength (green)
� 3,000 to 5,000 hours laser lifetime
I�ve no idea how long the two AAA batteries will last but in clear skies. Perhaps you can flash the laser on and off to conserve the batteries.
The laser should be held vertically and not horizontally. You should not treat it like a signal mirror and point it at someone. It is illegal to point it at an airplane. During a clear night, someone may be able to spot your beam and see it emanating from your location on the ground.
