A famous eclipsing binary in the constellation Auriga and one of the Kids (in Latin "Haedus"). It is also known as Haedus I and by an astonishing coincidence, its constellation mate, Epsilon Aurigae, which is the second Kid ("Haedus II"), is also a well-known (and even more remarkable) eclipsing binary.
Zeta consists an orange supergiant (spectral type K4) in orbit around a blue B star (type B5) with a period of 972.2 days (2.66 years). Because the orientation of the orbit lies within 3° of our line of sight, every 2.66 years the smaller B star hides completely behind the larger K star (which is about as wide as Venus's orbit), and the combined visual light drops by 0.15 magnitude (about 15%). Averaging 4.2 AU apart, the two go around each other in an elliptical orbit that takes them from 5.9 AU to 2.5 AU apart.