Home > Ephemeris Program, Observing, stars > 02/12/2015 – Ephemeris – The brilliant blue star in Orion: Rigel

02/12/2015 – Ephemeris – The brilliant blue star in Orion: Rigel

February 12, 2015

Ephemeris for Thursday, February 12th.  The sun will rise at 7:47.  It’ll be up for 10 hours and 18 minutes, setting at 6:06.   The moon, 1 day past last quarter, will rise at 2:52 tomorrow morning.

Two days ago I talked about the star Betelgeuse the bright red star in the top left of Orion’s upright rectangle.  Orion is seen in the south at 9 in the evening.  The blue-white star in Orion’s opposite corner is usually brighter.  It is Rigel whose longer Arabic name of which Rigel is the first part means Left Leg of the Giant.  Rigel is a giant itself, actually a super giant star, which is more a measure of its mass than its size, that of 21 solar masses.  Its surface temperature is more than twice as hot as the sun.  It is 120 thousand times as bright as the sun and 78 times its diameter.  Its distance is around 860 light years.  Those with telescopes might be able to spot a close companion star to Rigel, just at the edge of the bright arc light image of Rigel itself.

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

Addendum

Orion upright and due south. Created using Stellarium.

Orion upright and due south. Created using Stellarium.

Rigel A & B

Rigel with its companion star as photographed through a telescope. No attribution. Source: http://washedoutastronomy.com/content/urban-orion?page=1

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