Jimmy Westlake: Sea monster rising
Wedged in between the bright star Fomalhaut to the south and the glittering Pleiades star cluster to the east is the huge, lumbering constellation of Cetus, the Sea Monster. It ranks fourth in overall size among the 88 official constellations — only Hydra, Ursa Major and Virgo cover more area of the sky.
Yet, despite its large size, Cetus claims no star brighter than second magnitude and has only one of those.
Since the earliest times, Cetus has been identified with the mythological beast created by Poseidon’s anger at Queen Cassiopeia for daring to boast that her daughter Andromeda was more beautiful than the daughters of Poseidon (“Release the Kraken!”). The only way to stop the monster’s killing spree was to sacrifice the lovely Andromeda to him.
As she awaited her fate, chained to the rocks along the shore, the hero Perseus swooped in on his flying horse Pegasus and dangled the severed head of the Medusa before Cetus. The monster was transformed into a mountain of stone.
The original mythological sea monster bore little resemblance to a whale, but 17th century astronomers chose to portray the image of a whale among these stars, and the image seems to have stuck. There are even references that identify our Cetus as the giant cetacean that swallowed Jonah in the well-known Old Testament story.
In mid-November, Cetus will have risen completely above our southeastern mountains by 8 p.m. Its brightest star is Deneb Kaitos, the Whale’s Tail, visible just east of the brighter star Fomalhaut. From there, the Whale extends some 40 degrees to the north and east to the star Menkar, the Whale’s Nose, close to the little Pleiades star cluster. Menkar and four other stars form a distinctive pentagon shape that represents the head of the sea monster.
There are two more very interesting stars within the constellation of Cetus.
First is the star Tau Ceti, a near twin of our own sun, in terms of size and temperature, and only 11.9 light years away. In 2012, astronomers announced evidence for a family of five planets orbiting Tau Ceti, with one or possibly two orbiting in the so-called “Goldilocks zone” of habitability.
The star has figured heavily in many science fiction stories in the past and, no doubt, will continue to capture the imagination of stargazers and dreamers everywhere. Who knows — Tau Ceti one day might become home to a space colony as we leave our cradle behind.
The second star of note within the borders of Cetus isn’t even visible to the naked eye except for a few weeks out of each year. It is the star Omicron Ceti, also known as Mira, the Wonderful Star.
Mira is a long period variable star that first caught the attention of astronomers many centuries ago. When near maximum light, Mira sometimes can rival Cetus’ brightest star, Deneb Kaitos, although it typically maxes out slightly fainter.
When near minimum light, a telescope is needed to spot Mira at all. This remarkable star oscillates between these two extremes in a period of about 11 months.
Mira is now near its minimum brightness and invisible to the unaided eye, but its rapid climb to maximum brilliance should peak around the end of January. Keep an eye out for the Sea Monster’s “wonderful star” this winter.
Professor Jimmy Westlake teaches astronomy and physics at Colorado Mountain College’s Steamboat Springs Campus. His “Celestial News” column appears weekly in the Steamboat Today newspaper. Check out Jimmy’s new “2017 Cosmic Calendar” of sky events on his website at jwestlake.com. It features 12 of his best astro-photos and a day-by day listing of cool celestial events that you and your family can enjoy watching all year.
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