Delta Cephei is one of the most significant variable stars, the prototype of what are called "Cepheid variables".
    Through studies on the periods of the variability of Cepheid stars, it has been possible to more accurately gauge distances to outlying galaxies.

To the careful observer the change in magnitude is noticeable. Delta Cephei varies from 3.5 to 4.4 every 5 days 8 hours 47 minutes 31.9 seconds. Compare its magnitude with zeta Cephei, in the same field of vision. Zeta has a magnitude of 3.4. Thus delta will be equal to zeta at its maximum, while noticeably dimmer at its minimum.

To find delta Cephei it will be first be easier to hop from another star, mu Cephei, the star that William Herschel so enthused over for its particular shade of red that he named it the Garnet Star.

Delta Cephei is due east of mu Cephei; first you'll come to zeta. Centring this star brings delta to view: binoculars.

You will note the binary Krüger 60 very close to delta, to the south. The primary is only 9.8 visual magnitude, a red dwarf with another red dwarf as a companion, visible in larger telescopes (the companion's visual magnitude is only 11.4). This companion orbits every 44.7 years. The 2000 values are a Position Angle of 95º and a separation of 3.0".
    The binary is only 13.1 light years away; the companion has one of the smaller masses known, at only .14 of the Sun's mass. Its luminosity often changes quickly because of flares on its surface; this change is visible even with medium-sized telescopes.