Home > Ephemeris Program, stars > 02/18/2016 – Ephemeris – Castor and Pollux

02/18/2016 – Ephemeris – Castor and Pollux

February 18, 2016

Ephemeris for Thursday, February 18th.  The Sun will rise at 7:39.  It’ll be up for 10 hours and 35 minutes, setting at 6:14.   The Moon, 3 days past first quarter, will set at 5:28 tomorrow morning.

The star Pollux is at the head of the same named brother of Gemini the twins.  Castor is the  slightly dimmer star right above it.  Pollux is about 34 light years away.  It’s twice as massive as the Sun, and has run out of hydrogen in its core and is in the process of evolving into a red giant star.  One planet, twice as massive as Jupiter has been detected around it.  Castor is at 51 light years away.  There are 6 stars in its system.  The brightest three are visible in telescopes.  Each is a spectroscopic binary, meaning that the companion stars are detected by the Doppler shifts of the lines in their spectra as the stars orbit each other.   The Doppler shift is just one of the many pieces of information revealed by the spectroscope.

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


Castor and Pollux

Castro and Pollux with the bright Moon and other bright stars and constellations of winter. 9 p.m. February 18, 2016. Created using Stellarium.

Castor star system

The Castor star system exploded in this JPL/NASA infographic.

The entire infographic is here.

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