Tuesday, 19 August 2008
CHARM OPENS THE OBSERVATORY
What's going on in the Naval Observatory?
Walking up its hill and around its dome every day for exercise made our group a familiar sight. One day we charmed (behaved winsomely) an astronomer lady and she invited us in to explain why taxpayers fund this stargazing enterprise. At tour's end we were satisfied it was money well spent. Here's what we learned:
1. The Navy needs a standard time if ships are to navigate by the stars. Clocks around the world vary because they use different means of measurement. The fantastic consistency of cesium crystal vibrations is one "clock." The rotation of the earth is another and they do not agree. So now and again, they add or subtract a second to the official time to conform to earth rotation time. (which is more important) The "correct time", we learned is a decision and not a discovery. Ships normally navigate by GPS but the Navy insists on a backup system.
2. The Navy needs precise star charts as well as a standard time for accurate positioning and firing IF THE GPS FAILS . Stars move slightly over time and must be updated.
3.The Navy searches for potential KILLER ASTEROIDS, charting their paths, hopefully in time to divert them.
4. The Navy searches for planets outside our solar system. It looks at the wobble of stars that indicate orbiting planets. They've found hundreds.