Cetus constellation rises in the southeastern sky
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 Whale. 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 but one of those.
Since ancient 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. This mythological sea monster bore little resemblance to a whale, but seventeenth century astronomers chose to portray the image of a whale in these stars and the image somehow stuck.
In early November, Cetus is completely above our southeastern mountains by 8:00 PM. 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. Menkar and four other stars form a distinctive pentagon shape that represents the head of the sea monster.
There are two other noteworthy stars within the constellation of Cetus. First is the star Tau Ceti, a near twin of our own Sun. Because it is almost the same size, temperature, and color as our Sun, it makes a promising target for astronomers searching for Earth-like planets. At a distance of only 11.9 light years, Tau Ceti might become home to a space colony one day as we leave our cradle behind. So far, no planets have been identified orbiting Tau Ceti, but a large ring of rocky debris, not unlike our own asteroid belt, has been detected.
The second star of note within the borders of Cetus is only visible to the naked eye 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 can sometimes 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 eleven months. Mira is now near its maximum, so keep an eye out for this amazing variable star. ***