October 2014

Sun and Moon

FIRST QUARTER (half moon in the evening sky) falls on the  1st. FULL MOON occurs at 12:51 PM on the 8th, with LAST QUARTER (half moon in the morning sky) falling on the 15th. NEW MOON is on the 23rd and the second FIRST QUARTER for the month occurs on the 31st.

On the 24th the young lunar crescent will be visible with the naked eye from the Pacific ocean, southern North America, Central and South America. It may also be visible using an optical aid from parts of Western Africa. On the 25th it will be visible from most parts of the world. The predicted first visibility from South Africa will be on the 25th.

On the 6th at about 11:42 AM the Moon will be at perigee (closest approach to Earth) at a distance of about 362 480 km. It will be at apogee (furthest from Earth) at a distance of about 404 897 km on the 18th at about 08:06 AM.

A total lunar eclipse will occur on the 8th October, but unfortunately it will not be visible from South Africa.

Planetary and Other Events – Morning and Evening

Mercury is visible in the evening sky at the beginning of the month and in the morning sky late in the month. Unfortunately, Venus is too close to the Sun to be easily observed this month. Mars will be visible from sunset, setting around midnight at the beginning of the month and around thirty minutes earlier by month’s end. Jupiter is visible in the morning, rising around 04:00 AM at the beginning of the month and around 02:00 AM at months end. Saturn is visible during early evening setting around 22:00 PM at the beginning of the month and during twilight by month’s end. Uranus will be visible throughout the night during October. Neptune is visible until around 05:00 AM at the beginning of the month (around 03:00 AM by month’s end) and is well placed for evening viewing.

Several meteor showers are visible in October. The Southern and Northern Taurids which are active from the 1st October – 25th November (although peaking in November), and the Orionids which are active from the 2nd October – 7th November, peaking on the night of the 21st October. The Orionids are best viewed from midnight to 4:00 AM and the radiant is located just below the bright red star Betelgeuse in the Orion constellation. Viewing of the Orionids will be favourable this year.

The Evening Sky Stars

The winter Milky Way is still visible in October evenings, running from the stars of the Swan (or Northern Cross) through the dim stars of the Fox and the Arrow to Altair and the Eagle in the northwest, forming a glowing backdrop for the stars of the Archer and the Scorpion’s tail in the west and WSW, and finally reaching the stars of the Centaur, the Cross and the Fly low in the south. Musca (the Fly) is an interesting constellation with a curious history. Originally it was known as the Bee, then the Bee-fly, and later the Southern or Indian Fly. When the Northern Fly was eliminated as a constellation in 1929, the southern sky cornered the celestial fly market completely. Theta Muscae is unremarkable to the eye, but one component of this ‘double star’ is a massive object which ejects material so vigorously that it has blasted out a ‘bubble’ more than three hundred light years across in the surrounding interstellar material. Part of the ‘Coalsack’, a remarkable dark cloud of dust blocking almost all light from stars behind it, spills over into Musca from the Southern Cross. This cloud is about 550 light years away, 60 light years across and weighs about 3500 times as much as our sun. It is easily the most obvious dark cloud in our night sky, and is typical of areas where new stars can form.

Between the Scorpion and the Centaur are the Altar, the Level and the Wolf, while to the east of the Milky Way stretches a great expanse of sky with relatively few bright stars, dominated by birds and ‘water constellations’. In the south these include the Peacock (just west of the Altar), the Crane, the Goldfish, the Toucan, the Water Snake and the Phoenix. Almost surrounded by the stars of the last three constellations (plus the Clock) is the bright star Achernar high in the SE, the bright star at the delta of the celestial river Eridanus. Near the zenith is the bright star Fomalhaut in the Southern Fish, with the stars of the Water Carrier and the Sea Goat just to the north, and the Crane just to the south. Rising in the east is Cetus the Whale, while the Great Square of Pegasus (the Flying Horse) dominates the northeastern sky, flanked by the two Fishes (tied at their tails for some reason).

Not all constellations were always seen as we draw them today. The brightest star in the modern constellation of the Crane was described by the Arabs as ‘the bright one in the fish’s tail’, because they saw it as part of the tail of the Southern Fish. About 100 light years away and 380 times as bright as our sun, Al Nair is much hotter and younger than our sun. Almost all of the stars we see in our night sky are really brighter than our sun, even though the sun would appear the fourth brightest of the nearby stars if all were placed at the same distance. This is because most of the nearby stars are so much dimmer than the sun that they can only be seen through a telescope even though they’re close, while most of the stars we see with the naked eye in the night sky are so much brighter than the sun that they are easily visible at considerable distances.

The Morning Sky Stars

The early morning sky is dominated by the same bright stars that will shine in January evening skies after sunset. Almost overhead are the two brightest stars in the sky, Sirius and Canopus. Canopus would appear far brighter if they were at the same distance, but appears dimmer because it’s about 36 times as far away. Canopus is the brightest star in the giant ancient constellation of Argo Navis, the great ship of Jason and the Argonauts. Today this constellation, tangled in the Milky Way, has been subdivided into the Keel, the Rear Deck, the Sails and the Compass, with the Flying Fish zooming by the Keel and the Goldfish swimming ‘below’ (i.e. to the west). Dorado the Goldfish does not refer to the usual pet variety, but is named after a Hawaiian deep sea fish, usually called mahi-mahi, and is sometimes called the Swordfish. Rising in the southeast are the stars of the Cross and the Fly, with the Pointers and the Southern Triangle near the horizon. High in the southwest is the bright star Achernar, from which the Celestial River winds north and east toward Orion.

Orion the hunter is high in the north, with Taurus the Bull charging from the northwest. Low in the north is Auriga the Charioteer, which in most drawings of constellation figures shares a star with the Bull, probably making for a fairly wild chariot ride. Below and to the right of Orion (for an observer facing north) are the stars of the Twins. Of the two bright stars in the twins, Castor (below and to the left of Pollux) is a sextuple star, with three pairs of stars orbiting each other. The two brightest can be seen in a telescope, and the other four are ‘red dwarf’ stars far dimmer than our sun. Very high in the north is Lepus the Hare, just above Orion’s feet (Orion being ‘upside down’ for southern hemisphere sky-watchers). To the right of the Hare is the Big Dog, including bright Sirius, while the Small Dog (with the bright star Procyon) can be found directly to the west of Orion. Orion’s belt was seen by various peoples in southern Africa as three zebras, three lions, three dogs, or three pigs. The Xhosa took a less imaginative view, calling it ‘three stars in a line’.

Nicola Loaring 30 Sept 2014

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