Full sky chart for the month of October

October 2008 Night Sky

—CHARLIE CHRISTMANN

A New Member of the Solar System

The International Astronomical Society as added a fifth dwarf planet to the solar system. Discovered by a group led by Jose-Luis Ortiz of the Sierra Nevada Observatory in Spain in 2004, the object is now named Haumea, after the goddess of childbirth and fertility in Hawaiian mythology. Haumea is accompanied by two small moons named Hi’iaka and Namaka, after the two children born to the goddess Haumea.

Observations indicate this dwarf is composed of solid rock core with an icy crust about a third the mass of Pluto. But it spins so fast, one revolution every four hours, its diameter is about the same as Pluto. But the fast spin causes the equator to expand and the poles to pull inward toward the center making the object look more like a football from the side. The two moons appear to be chunks knocked from the main body by some previous collision.

Haumea is a member of the trans-Neptunian class of objects, currently about 50 times as far from the Sun as Earth. The dwarf planet will swing as close as 35 times the Sun-Earth distance.

The Sea Goat

Capricornus is located almost due south about 30 degrees above the horizon this month at 9:00 pm. This is one of the dimmest constellations in the sky, yet it is a member of the Zodiac. The Zodiac is a ring of 12 constellations recognized by the Babylonians that follow the path of the sun across the heavens and are associated with the astrological signs.

The brightest star in Capricornus lies in the farthest northwest part of the constellation. Deneb Algedi, or Delta Capricorni and shines at magnitude 2.85. It lies 38 light-years away from the sun. The next brightest star is all the way across the constellation. Beta Capricorni is a double star that lies just over 20 degrees west of Deneb Algedi. The brighter member of Beta Capricorni is Dabih at magnitude 3.05. Dabih is an Arabic name that means “butchers”. It lies 344 light-years away. The dimmer companion is magnitude 6.09 and lies 313 light-years away.

One legend links this pattern to Babylonian Ea, an ancient god with a human upper body and the tail of a fish who emerged from the sea to bring knowledge and culture to humans. In another myth, this constellation is sometimes identified as Amalthea, the goat that suckled the infant Zeus after his mother Rhea saved him from being devoured by his father Cronos in Greek mythology. The goat’s broken horn was transformed into the cornucopia or horn of plenty.

Currently, if you have a telescope, Neptune is located in this constellation just above and to the left of the eastern most star, Delta Capricornus.

Little Horse

In the south, about 50 degrees above the horizon is the second smallest constellation in the sky, Equuleus, the little horse. The constellation is positioned between Delphinus and Pegasus. Its brightest star is Kitalpha, at magnitude 3.92. Get out your binoculars and look for Gamma Equuleus. This is a variable star, ranging between magnitudes 4.58 and 4.77 over a period of around 12½ minutes.

Equuleus is associated with the foal Celeris, meaning “swiftness” or “speed”, who was the offspring or brother of the winged horse Pegasus. Celeris was given to Castor by Mercury. Some myths say that Equuleus is the horse struck from Neptune‘s trident during the contest between him and Athena when deciding which would be the superior.

The Dragon

Draco, the dragon, is a circumpolar constellation visible all night from northern latitudes. Look for this figure about 45 degrees above the north-northwest horizon about 9:00 pm. Eltanin, is the brightest star in Draco, with a visual magnitude of 2.24. One of the better known deep-sky objects (you definitely need a good telescope) is the Cat’s Eye Nebula (NGC 6543), a planetary nebula that looks like a blue disc.

The Pharaoh Khufu ruled ancient Egypt around 2550 BC and was buried in the largest of the Giza pyramids when he died. During his time, Thuban, in Draco, was the pole star. Khufu’s burial chamber was fashioned deep inside the Great Pyramid. Two skinny shafts bore outward from the chamber, one pointed toward Thuban, the other toward Orion’s belt.

Thuban was the naked-eye star closest to the north pole from 3942 BC, but due to the Earth’s procession, it moved farther north. In 1793 BC, it was replaced by Kappa Draconis as the pole star. (Today Polaris is the current pole star.) After moving nearly 47 degrees off the pole by 10000 AD, Thuban will gradually move back toward the north celestial pole. In 20346 AD, it will again be the pole star.

The Planets and Moon

Mercury is a morning planet. Look for it low in the east before sunrise. Look 45 minutes before sunrise on the 27 th to find Mercury and the Moon. Using binoculars, Mercury will be to the upper left of the Moon.

Venus is the evening “star” showing up bright in the west after sunset. Late in the afternoon on the 1st, look for the Moon about 30 degrees to the left of the Sun. With binoculars, look at the Moon and you can see Venus 6 degrees above the Moon. And again on Halloween, find the waxing Moon and Venus paired in the west about 40 minutes after sunset.

Mars can be found low in the west after sunset.

Jupiter is in Sagittarius, located in the southwest after sunset. The Moon and Jupiter will be separated by only 5 degrees on the 6th after sunset. Antares will be below and to the right on the horizon one hour after sunset in the south southwest.

Saturn rises in the east from 5:00am early in the month to 4:00am late in the month. One hour before sunrise on the 25th, find Saturn and the Moon separated by only 6 degrees.

Uranus is located in Aquarius, 45 degrees above the horizon in the southeast at 9:00 pm.

Neptune is in Capricornus.

The Moon is full on the 7th and new on the 28th.

Full sky chart is for October 15th at 9:00pm.