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Posts Tagged ‘circumpolar.’

09/07/2017 – Ephemeris – Capella rising

September 7, 2017 1 comment

Ephemeris for Thursday, September 7th. The Sun will rise at 7:12. It’ll be up for 12 hours and 55 minutes, setting at 8:07. The Moon, 1 day past full, will rise at 9:08 this evening.

For those with the advantage of a low northern horizon, will see a bright star moving nearly parallel above the horizon over the evening hours or notice its change in position from night to night, moving to the northeast. The star is Capella, northernmost of the bright winter stars. It never quite sets for locations north of the latitude of Ludington (44° N), meaning it’s circumpolar like the Big Dipper. It’s slow motion, due to its position close to the north pole of the sky sometimes makes it seem odd. I’ve gotten several calls about it over the years. Capella is the brightest star in the constellation Auriga the charioteer, a constellation I see as a pentagon, with a small triangle of three stars on one side. I’ll wait until the winter season to talk further about them.

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

Addendum

Capella rising

Capella appearing to rise like an aircraft taking off. Shown here at hourly intervals from 9 p.m. to midnight. Created using Stellarium and GIMP.

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10/06/2015 – Ephemeris – Deneb our home-town star

October 6, 2015 Comments off

Ephemeris for Tuesday, October 6th.  The Sun will rise at 7:46.  It’ll be up for 11 hours and 27 minutes, setting at 7:14.   The Moon, 2 days past last quarter, will rise at 2:36 tomorrow morning.

We, here in Traverse City, Michigan have a pretty unique relation to the bright star Deneb, as is any location near 45 degrees north latitude.  Tonight at 9:23  Deneb will be three-quarters of a degree due north of the zenith.  Due north means that it’s on our meridian, a line you may remember from your school days.  For astronomers it passes from the north point on the horizon, through the overhead point or zenith to the south point on the horizon.  Also due to our latitude Deneb is circumpolar, meaning that it doesn’t quite set on a clean northern horizon.  Deneb and 56 other stars are used for celestial navigation, which is still taught in case the GPS system goes down due to solar or enemy action.

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

Addendum

Deneb nearly at the zenith

Deneb nearly at the zenith from Traverse City. Created using Cartes du Ciel.

Deneb nearly at the horizon

Deneb is close to the horizon due north. Created using Cartes du Ciel.

11/25/2014 – Ephemeris – Cassiopeia the constellation

November 25, 2014 Comments off

Ephemeris for Tuesday, November 25th.  The sun will rise at 7:52.  It’ll be up for 9 hours and 14 minutes, setting at 5:06.   The moon, 3 days past new, will set at 8:33 this evening.

Nearing the zenith at 8 p.m. is the W shaped constellation of Cassiopeia the queen.  It’s actually just north of the zenith and since we’re half way from the equator and the north pole at near 45 degrees north, Cassiopeia will not set.  Cassiopeia we say is circumpolar.  Cassiopeia will rise is set if you’re in Florida.  In Antarctica Cassiopeia is a just rumor, just as the Southern Cross is to us in Michigan since it never rises.  Cassiopeia lies against the Milky Way, so there are a lot of star clusters in it.  Unfortunately they can be seen only in telescopes.   In 1572 the last of the pre-telescopic astronomers Tycho Brahe discovered a bright star that suddenly appeared.  His discovery broke open the Aristotelian belief that the heavens were changeless.

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

Addendum

Cassiopeia at the zenith.

Looking straight up at the zenith, facing the south, Cassiopeia is just north of the zenith. The lines are radiating from the zenith. where the + sign is. Created using Cartes du Ciel.

My neck hurts just making this chart.