Looking Up: Meet the King of the North

Peter Becker

If you can take your eyes off the King of Planets, brilliant Jupiter dominating the south, turn around and behold the king of the constellations, King Cepheus, reigning in the northern sky.

Cepheus is not particular brilliant. Just ask his wife Queen Cassiopeia! Actually, this is no reflection on Cepheus; its stars are not as bright as in others. Yet, the star group was named by the Greeks to symbolize one of their mythological kings.

Nonetheless, Cepheus is fairly easy to see. Its principal stars form a shape of a house, with a sharp peak. Cepheus is one of several constellations that are circumpolar as seen from mid-northern latitudes.

That means as they whirl once around the point very near the North Star every 24 hours, they completely miss the flat horizon, never setting. The others are Cassiopeia the Queen, Camelopardalis the Giarafe ( a very faint group of stars), the Big Dipper portion of Ursa Major the Great Bear, Ursa Minor the Little Bear (otherwise called the Little Dipper), and Draco the Dragon.

As seen on autumn evenings, Cepheus is high up, above the North Star; as a “house” it appears upside down, with its “peak” at the bottom. The constellation of the king’s mythological wife, Cassiopeia, is to the right, her five principal stars shaped like a “W” on end.

Cepheus has two particularly interesting stars for the backyard observer.

Delta Cephei is the prototype of a famous variety of variable stars. The star dims from magnitude +3.4 to +4.4 and back every 5.4 days. The change is easy to see with eyes alone, comparing the star with nearby stars of steady glow.

The period of variability is linked with the luminosity of this type variable star. Cepheid-type variables seen elsewhere in the galaxy reveal how far away they are by measuring their apparent brightness. They have even been detected in far-off galaxies, revealing the galaxy’s distance and some sense of the scale of the universe.

Also look for Mu Cephei, visible to unaided eyes in reasonably dark skies. The star also varies in brightness, from 3rd to 5th magnitude. Binoculars will immediately show its deep red-orange hue. Famed 19th century English astronomer William Herschel described the color as “garnet.” Ever since the star has been nicknamed the Garnet Star. This massive red giant star, if it were placed in exchange for our sun, would extend as far as the orbit of Saturn.

The Milky Way Band passes through Cassiopeia and Cepheus. You need to be away from town or city lights to see it, and there must be no moonlight. Enjoy sweeping this area with binoculars or a telescope.

Note about Pluto

Last week’s column referred to Pluto and its reclassification in 2006 by the International Astronomical Union (IAU), which changed its status as a planet to a new category of “dwarf planets.” The reference to the “astronomical community” as making this change was misleading.

An astronomy graduate student, Laurel Kornfeld, pointed out that the decision was made by only 424 members of the IAU who voted on the matter, out of some 10,000 members. The decision remains a matter of debate among astronomers.

Last-quarter moon is on October 30.

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Keep looking up!