Home > Constellations, Ephemeris Program, Observing > 10/18/2012 – Ephemeris – Autumn wonders for binoculars or small telescope: The Alpha Persei Association

10/18/2012 – Ephemeris – Autumn wonders for binoculars or small telescope: The Alpha Persei Association

October 18, 2012

Ephemeris for Thursday, October 18th.  The sun will rise at 8:02.  It’ll be up for 10 hours and 49 minutes, setting at 6:52.   The moon, half way from new to first quarter, will set at 9:17 this evening.

When is a star cluster not a star cluster?  When it’s an association.  That is when it has begun to dissipate because the gravitational force of the group cannot hold it together.  The central stars of the Big Dipper belong to The Ursa Major Association.  Below the W shaped constellation of Cassiopeia in the northeast at 9 or 10 p.m.  Is the constellation of Per-seus or Pers-e-us as it is usually pronounced.  Its brightest star is Mirfak with a designation of Alpha Persei.  There are some stars there to the naked eye, but with binoculars there are a great many stars just below naked eye visibility.  This is called the Alpha Persei association.  The star groups I’ve talked about this week are just some of the wonders visible in a simple pair of binoculars.

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

 

Addendum

The constellation Perseus.  (Stellarium spells Alpha Persei Mirphak, not Mirfak.  Star name spelling can be something variable.)

The constellation Perseus in the northeast at 10 p.m. on October 18, 2012.  Created using Stellarium.

The constellation Perseus in the northeast at 10 p.m. on October 18, 2012. Created using Stellarium.

The Alpha Persei Association in a binocular view.  Created using Stellarium.

The Alpha Persei Association in a binocular view. Created using Stellarium.

 

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