01/10/2017 – Ephemeris – Rigel, the blue super-giant in Orion
Ephemeris for Tuesday, January 10th. The Sun will rise at 8:17. It’ll be up for 9 hours and 4 minutes, setting at 5:22. The Moon, 2 days before full, will set at 7:10 tomorrow morning.
Yesterday I talked about the star Betelgeuse the bright red star in the top left of Orion’s upright rectangle. Orion is seen in the southeast 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 23 solar masses. Its surface temperature is twice as hot as the Sun. It is 120 thousand times as bright as the sun and 79 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.