Southern Sky News for 2008 October

Find out about the Moon, planets, stars and constellations for October, as well as an update about October Astronomy Month, in this month's edition of Southern Sky News.

The Moon and planets in October

Mercury is too near the Sun to be seen this month. It lies between us and the Sun on October 06. Look for Mercury in the morning sky in November.

Venus shines brilliantly each evening this month, visible soon after sunset in the west as the Evening Star. During the last week of October, Venus passes by the red star Antares (in Scorpius). Venus is moving towards Jupiter, and the two will have a close approach at the end of November.

Mars can be seen for the first two weeks low in the west just after sunset. During the first week, compare the colour of Mars with that of Antares, the reddish star higher up in Scorpius. Near the end of the month Mars disappears into the solar glare. The Red Planet is furthest from the Earth (2.503 AU) during 2008 on October 31.

Jupiter is the second-brightest star in the sky this month, high overhead at sunset, setting after midnight. October evenings is a great time to look at the giant planet and its bright moons.

Saturn starts the month too near the Sun to be seen. By the middle of October it becomes visible in the morning sky, and is easier to see at month's end in the east-northeast before sunrise. It's rings are becoming increasingly "narrower" as they turn more edge-on as seen from Earth; in September next year, they will be exactly edge-on.

The Moon is visible at sunset for the first two weeks of October. Full Moon is on October 14, and New Moon is on October 28. On October 31, the very thin crescent Moon is close to Antares in Scorpius.

The stars in October

October is the last month to get a good look at Scorpius in the evening sky.

Around the beginning of the month, just after sunset, Scorpius is prominent high up in the west. Its bright reddish star Antares is a prominent feature in the sky at this time of the year. Crux is low down in the south-southwest.

The two Pointers, that point towards Crux, are also quite low down. The brightest of these two stars, alpha Centauri, is the second-closest star to our solar system. The closest star is Proxima Centauri, a faint red dwarf star, 30,000 times smaller than our Sun. Results published last month, summarizing many years' work of the search for planets around Proxima, concluded that it doesn't have its own planetary system.

Meanwhile, our own solar system has just acquired a new planet! In September the International Astronomical Union announced that an object discovered in 2004, and since studied closely, qualifies to be classified as a dwarf planet. It has been named Haumea, and is our solar system's fifth dwarf planet (the others being Ceres, Pluto, Makemake, and Eris). Haumea orbits the Sun every 285 years, and has two moons of its own.

The long arm of Crux points towards the bright star Achernar, high up in the south-east. This odd star rotates so rapidly that it takes on an egg shape. Achernar is 80 times larger and 3,000 times brighter than our Sun, but because it is also 10 billion times further away, we see it merely as a bright star set in our night sky, one of 4 billion stars in the Milky Way. Our little Sun, our local star, remains the primary source of energy in the solar system we call home.

The bright star in the north-northwest is Vega (in Lyra the Harp), a bright northern visitor we see for a brief part of the year. Vega is one of the closer stars to us, some six times further away than Proxima Centauri. Infra-red studies of Vega show that it is surrounded by a disk of gas and dust, the possible building blocks of a planetary system. Although Vega has a brilliant white colour, it often shows beautiful colour changes because its light, struggling to get through the atmosphere, twinkles with the colours of the rainbow. Of course, any bright star, low above the horizon, can produce this pretty star-show.

Above Vega and slightly fainter is Altair (in Aquila the Eagle). It is slightly closer to us, only four times the distance to Proxima. Just like Achernar, Altair also rotates rapidly and is egg-shaped.

Not all bright stars are necessarily close to our solar system. Antares in Scorpius, for example, is 600 light years away, or 140 times the distance to Proxima. But while Proxima is a red dwarf star, Antares is a red giant star. And "giant" is certainly the correct word: Antares is 300 million times larger than our Sun! If we were to magically transport Antares and plop it down in the centre of our solar system, the edges of this star would reach out to far beyond the orbit of Mars! Thank heavens its 600 light years away!

By midnight, Scorpius is setting in the southwest; the head of the scorpion is below the horizon and only the curved tail remains visible. Crux is at its lowest point in the south, pointing upward to Achernar. The bright star in the southeast is Canopus. This is a good time to spot the two Cape Clouds, the Large and Small Magellanic Clouds. You can use the False Cross to find the Large Cloud, and then use Canopus and the Large Cloud, to find the Small Cloud. Facing east, you'll find Orion perched on the horizon. To his right is brilliant Sirius. Left of Orion is the red star Aldebaran (in Taurus) with the Pleiades (Seven Sisters, isilimela) further to the left. Due north the Square of Pegasus (the Flying Horse) can be seen. The bright star in the northwest is Altair (in Aquila the Eagle).

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Before sunrise, look due north, a short distance above the horizon, for the bright star Capella (in Auriga the Charioteer). Above Capella, high up, lies Orion, standing on his head. Taurus the Bull lies below and to the left of Orion. To the right, in the north-northeast, lie the two bright stars of Gemini the Twins. High overhead is bright Sirius in Canis Major (the Big Dog). Bright Canopus is also high up. In the east, the lone bright star is Regulus in Leo the Lion.

By the end of October, Scorpius the Scorpion is heading down in the west-southwest after sunset. The very bright star low in the northwest is Vega (in Lyra the Harp). To the right of Vega is Deneb (in Cygnus the Swan). High above Vega is the bright star Altair (in Aquila the Eagle). Look in the north-northeast for the large Square of Pegasus. High in the southeast is Achernar, and much lower down is Canopus. Crux and the Pointers are low in the south-southwest. The bright star directly overhead is Fomalhaut (in Piscis Austrinus).

At midnight, Crux and the Pointers are low in the south, while high overhead is Achernar. High in the southeast is the bright star Canopus – try and spot the Large and Small Magellanic Clouds, too. Shining brilliantly due east is Sirius. To the left of Sirius is Orion the Giant, and further left is Taurus the Bull. Very low in the north-northeast is Capella (in Auriga). The Square of Pegasus is prominent in the northwest.

In the early morning sky, look high in the northwest for Orion the Giant, with Taurus the Bull below him in the northwest, and Sirius (in Canis Major) above. Below Orion to the north-northwest is the bright star Capella (in Auriga the Charioteer). Gemini the Twins lies in the north-northeast. In the northeast the Sickle of Leo can be seen, with its bright star Regulus (Saturn lies to the right of Regulus). High in the southeast lies Crux and the two Pointers. Overhead is the brilliant Milky Way, with the bright star Canopus off to one side. Below Canopus to the southwest lies the bright star Achernar (in Eridanus the River).

2008 October sky diary

Date	Event
01	At sunset, Venus shines brightly in the west and will be the first star visible. High overhead is Jupiter, only slightly fainter. As twilight deepens, look for Mars below Venus. Between Venus and Jupiter is a bright red star, Antares, the Heart of the Scorpion. This evening, the very thin lunar crescent makes an appearance, below and to the left of Venus, low in the twilight sky. Both Mars and Venus lie 5 degrees from the Moon.
02	The slender lunar crescent can be seen above, left of Venus in twilight. Mars is below Venus, setting earlier each evening.
03	After sunset, look for the crescent Moon above Venus and below red Antares (in Scorpius). Notice reddish Mars below Venus, setting.
04	As night falls, look for the crescent Moon in the west, which lies just above red Antares (in Scorpius). From other parts of the world, the Moon will occult Mars today.
05	Venus and Mars can be seen at sunset in the west. The little star close by Venus is Zubenelgenubi. The Moon is midway between Antares and Jupiter. This evening, the Moon is at the point in its orbit furthest from Earth (although it won't look smaller!)
06	The Moon is near Jupiter tonight, close to the star that forms the lid of the Teapot star pattern (Sagittarius). Venus and Mars can be seen at sunset in the west. The little star close by Venus is Zubenelgenubi.
06	Mercury reaches inferior conjunction
07	The Moon, near Jupiter, is at First Quarter tonight.
08	At sunset, the Moon is high overhead, with Jupiter nearby.
10	Neptune is less than a degree from the Moon tonight; from other parts of the world, the Moon occults Neptune.
14	It is Full Moon tonight. Soon after sunset the Moon looms large in the east.
15	In the morning sky before sunrise, low in the east, Saturn can be seen rising. In the evening sky, Venus and Jupiter are prominent. Mars is becoming more difficult to see as it approaches closer to the Sun each evening. Soon after sunset, the large Moon rises in the east. By midnight, Jupiter is very bright low in the west-southwest. Orion has risen above the eastern horizon, accompanied by brilliant Sirius to its right, and red Aldebaran to the left. Further left of Aldebaran is the Seven Sisters open cluster.
17	The Moon is at perigee today.
20	At sunset, Venus is in the claws of the Scorpion, heading closer to Antares each evening.
21	The Moon is at Last Quarter phase; it rises around midnight and is high in the sky at sunrise. Castor and Pollux lie a few degrees away from the Moon this morning. The Orionid meteor shower peaks tonight, but the bright Moon will interfere with observations.
22	Mercury is at greatest elongation in the morning sky.
23	In the morning sky, the crescent Moon is above, left of Regulus (in Leo).
24	The crescent Moon is near Regulus (in Leo) in the morning sky.
25	The thin crescent Moon is near Saturn in the morning sky.
26	Venus is near Antares in the evening sky. After tonight, it moves further away from the star.
28	It is New Moon tonight.
30	A very thin crescent Moon returns to the evening sky tonight, low in the west-southwest.
31	In the morning sky, Sirius shines brightly overhead, with Orion the Giant and Taurus the Bull prominent high in the northwest. Saturn is the brightest star in the east-northeast. Just after sunset, the thin crescent Moon is very close to the red star Antares; from other parts of the world, the Moon will occult Antares today. Venus lies above the Moon and Jupiter higher up. By midnight, Jupiter is setting, and is very low in the west-southwest. In the east, Sirius shines brightly, with Orion the Giant and Taurus the Bull to its left.

/ph

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Southern Sky News for 2008 October

The Moon and planets in October

The stars in October

2008 October sky diary

What's your opinion?

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