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Posts Tagged ‘Polaris’

09/30/2013 – Ephemeris – The constellation of Cassiopeia the queen

September 30, 2013 Comments off

Ephemeris for Monday, September 30th.  The sun will rise at 7:39.  It’ll be up for 11 hours and 44 minutes, setting at 7:24.   The moon, half way from last quarter to new, will rise at 4:07 tomorrow morning.

The stars of the autumn skies slowly are replacing the summer stars from the east.  Look in the northeastern sky by 9 p.m. and you can find the W shaped constellation of Cassiopeia the queen.  Cassiopeia is so far north that it never sets for us in Michigan.  It is opposite the pole star Polaris from the Big Dipper.  There’s a dim star that appears above the middle star of the W which turns the W into a very crooked backed chair.    Cassiopeia, in Greek mythology, represents a queen of ancient Ethiopia, the W represents the profile of her throne.  She enters in to the great autumn story whose other characters are also seen in the stars as the constellations Andromeda, Pegasus, Perseus, Cetus and her husband Cepheus.

Times are for the Traverse City/Interlochen area of Michigan.  They may be different for your location.

Addendum

Cassiopeis, in the northeast is opposite Polaris from the Big Dipper.  For 9 p.m. on September 30th.  Created using Stellarium.  Artistic credit:  Johan Meuris.

Cassiopeis, in the northeast is opposite Polaris from the Big Dipper. For 9 p.m. on September 30th. Created using Stellarium. Artistic credit: Johan Meuris.  Click to enlarge.

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11/22/2012 – Ephemeris – Celestial navigation in the days of the Pilgrims

November 22, 2012 Comments off

Ephemeris for Thanksgiving Day, Thursday, November 22nd.  The sun will rise at 7:48.  It’ll be up for 9 hours and 19 minutes, setting at 5:08.   The moon, 2 days past first quarter, will set at 2:58 tomorrow morning.

Back in the days of the Pilgrims navigation was much less certain than it is today.  At the mercy of the winds and weather, sailing took a lot of courage.  Celestial navigation took the form of measuring the altitude of the pole star Polaris at night and the sun at noon.  That and tossing a log overboard attached to a rope with knots at regular interval to gauge their speed and progress.  That’s where we get the term knots as a measure of speed for nautical and aviation use.  Today we have GPS to tell us where we are.  However that is based on the position of not stars, but quasars, bright nuclei of distant galaxies, whose motions are currently too small to measure.  Have a happy Thanksgiving.

Times are for the Traverse City/Interlochen area of Michigan.  They may be different for your location.

Addendum

 

nasa-map_GPS Quasars

All sky map of quasar locations used as the celestial markers for the GPS system. Chart by David Bobolz, US Naval Observatory.

The chart above is from an article in the Telegraph.