jm + precession   1

The 26,000-Year Astronomical Monument Hidden in Plain Sight at the Hoover Dam
This is amazing! I wish I'd noticed it when I visited Hoover Dam.
The center of the circle traced by the axial precession is actually the massive flag pole in the center of the plaza. This axial circle is prominently marked around the pole, and the angle of Polaris was depicted as precisely as possible to show where it would have been on the date of the dam’s opening. Hansen used the rest of the plaza floor to show the location of the planets visible that evening, and many of the bright stars that appear in the night sky at that location.

By combining planet locations with the angle of precession, we are able to pinpoint the time of the dam’s completion down to within a day. We are now designing a similar system — though with moving parts — in the dials of the 10,000 Year Clock. It is likely that at least major portions of the Hoover Dam will still be in place hundreds of thousands of years from now. Hopefully the Clock will still be ticking and Hansen’s terrazzo floor will still be there, even if it continues to baffle visitors.

(Via Tony Finch)
hoover-dam  history  precession  astronomy  long-now  polaris  vega  thuban  stars  clocks 
24 days ago by jm

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