Generalities: it is a beautiful important zodiacal constellation . It is the  zodiacal constellation  pushed more northwards on the celestial vault. The Sun  enters it just after the solstice of June and remains up to the end of the second decade of July. This constellation transits at midnight during the month of January.

Origins and mythology: it represents Castor and Pollux, the twins, children of the queen of Sparta, Leda. Pollux was the only one to be immortal and when his twin brother was killed, he begged the gods to make him immortal. Pollux was heard and Castor was brought to life again.

Stars: Castor and Pollux, of magnitude 1.58 and 1.14 respectively, master this constellation. Pollux is therefore the brightest and it is of orange color (17° star of the whole sky for brightness). On the contrary, Castor is white, and it is also a double star which can be observed by good  amateur tools. Pollux is 35 light-years far, while Castor is 45 light-years far. Moreover  in the Twins there is a third star of  magnitude inferior to 2. It is gamma, named Alhena and of magnitude 1.93, a white  star  that is 105 light-years far.Then there are  other two stars of magnitude inferior to 3, and other 8 of  magnitude inferior to 4.
 

Table of stars brighter than magnitude 3.5
 
 

Star	Proper name	Magnitude	Spectrum	Colour	Distance (light-years)	Notes
Beta	Polluce	1.14	K0	orange	36
Alpha	Castore	1.56	A0	white	45	Narrow visual double star
Gamma	Alhena	1.93	A0	white	85
Mu	Tejat	2.88 (variable)	M3	red	231
Epsilon	Mebsuta	2.98	G8	orange	685
Eta	Propus	3.1 (variable - max)	M3	red	186
Csi	Alzirr	3.36	F5	white-yellow	75

Other objects: it shows a nice open cluster, M35, which can be observed with  normal binoculars. There is also an interesting planetary nebula.
 

Go back to constellations index
 

Go back to Home Page