Stars over Sisters 10/01/2019

After crossing the threshold from summer to fall late last month, October’s arrival will ensure cooler temperatures and longer nights as the new season progresses. When skies clear at night, the earlier sunsets and later sunrises will be perfect for doing some serious stargazing. The advancing season also causes more autumn constellations and other intriguing celestial objects to wheel into view.

One of the “new” constellations to take note of this month is Cetus the Sea Monster. According to Greek mythology, princess Andromeda was sacrificed to the horrible sea monster, Cetus, as punishment for her mother’s (Cassiopeia) bragging. In the myth, the boasting of her daughter’s beauty greatly angered Poseidon, god of the sea, and the sea nymphs. To punish them Poseidon sent Cetus to ravage their land.

In an effort to please Poseidon, king Cepheus and queen Cassiopeia were required to sacrifice their daughter to the sea beast by chaining her to a rock. But before Cetus could get to her, Perseus the Hero arrived on the scene just in time and saved Andromeda by turning the monster to stone. The two would later marry. Cetus is usually depicted with forefeet, a large jaw, and scales like a sea creature, but some cultures saw Cetus as a whale.

Cetus is found in our southeastern sky, and at least part of the constellation is visible between latitudes +70 degrees and -90 degrees. Its neighboring constellations include Aries, Pisces, Aquarius, Sculptor, and Eridanus. The brightest star in this incredibly large constellation (fourth biggest) is Beta Ceti, otherwise known as Deneb Kaitos (not to be confused with Deneb in Cygnus). This star is an orange giant, meaning it left the main sequence stage of star evolution and is on the path to becoming a red giant.

An amazing object deep within the constellation is NGC 17. It is a spiral galaxy that formed when two disc galaxies merged. NGC 17 has a single nucleus with a blue central disc and tidal tails indicating it used to be two separate galaxies. This object is located at a distance of approximately 250-million light-years.

The Orionid meteor shower peaks on the evening of October 21 and morning of October 22. The best time to look for them is two or three hours before dawn. This year, unfortunately, a waning moon just a day or two past last quarter will interfere. Still, rates of 10 to 20 per hour are possible. The fast-moving meteors are the result of debris shed from Halley’s Comet and seem to originate from a point in space near Orion’s upraised club.

Jupiter and Saturn continue to shine brightly in the southwestern sky throughout the month, though Jupiter sets at 8:30 p.m. local time by late October. Mars emerges in the morning sky, also late in the month. The two inferior planets lie very low in the west. The best opportunity to see them will come on October 29, half an hour after sunset as both Venus and Mercury will appear just above the horizon beneath a two-day-old crescent moon.

This month the moon will be at first quarter on October 5 as 48 percent of its disk will appear illuminated. The full moon rolls around on October 13, which, despite its magnificence, makes stargazing quite difficult because of the extreme brightness. Last quarter arrives on October 21, when 51 percent of the moon will be lit, and the moon will go dark on October 27 — the perfect time to go out and look at those beautiful

stars!

To learn more about astronomy, consider attending Sisters Astronomy Club’s final starwatch of the season, to be held at Sisters Park and Recreation District on Saturday, October 26 beginning at 7:30 p.m. Following a brief presentation, telescopes will be made available at the north end of the parking lot with which to view selected celestial objects. The event is free and all are welcome.