October is a good time for observers located in equatorial and southern latitudes wanting to view Mercury, as it will be visible throughout the month. During this time the planet can be spotted just south of due west. When viewed half an hour after sunset from latitude of 35S (e.g. Sydney, Australia), Mercury is about 9 degrees above the horizon on October 1st. It then climbs gradually higher as the month progresses until it reaches a peak altitude of nearly 18 degrees on October 26th. On this date, Mercury also reaches greatest eastern elongation (24 degrees).
Mercury brightness changes little during October. The planet starts the month at magnitude –0.4 before fading to magnitude -0.1 at months end. Unfortunately, the planet is not suitably placed for observers from northern temperate latitudes.
Venus remains a superb morning object this month, although the magnitude of the planet fades slightly from –4.1 to –4.0. During this time, the phase of Venus increases from 71 to 81 percent. The planet starts the month in Leo before crossing into Virgo on October 23rd, remaining there for the rest of the month. During October from northern latitudes Venus rises almost 3.5 hours before the Sun. It is currently better placed for northern hemisphere observers, hence the period of visibility during October for equatorial and southern hemisphere latitudes is up to an hour or two less.
The waning crescent Moon will pass 6 degrees south of Venus on the morning of October 12.
Mars almost keeps its distance from the Sun this month as they move on their eastward journey against the fixed stars. The "Red planet" starts the month in Libra, races through Scorpius before ending the month in Ophiuchus. Now shining at magnitude 1.2, the planet is visible low down to the southwest at dusk and sets just under 2 hours after the Sun from northern temperate latitudes. The period visibility is considerable better for southern hemisphere observers.
Incidentally, Mars is now 2 AU distant from the Earth and the apparent size of the planet has now shrunk to less than 5 arc seconds; which is not much greater than that of Uranus. There are a couple of interesting phenomena during October. On October 18, a waxing crescent Moon will pass 2 degrees north of Mars and on October 20, Mars will pass less than 4 degrees north of Antares (mag. 1.0), the red supergiant star. Antares has often been called the "Rival of Mars" due to its striking deep red colour. This conjunction presents an interesting opportunity for observers to compare the colour and brightness of the two objects.
Jupiter is a brilliant object that now rises in the early evening for northern hemisphere observers and a little later for those located further south. It remains visible for the remainder of the night. The giant planet is located in Taurus, a few degrees to the northeast of orange/red star Aldebaran (mag. 0.9) and the large sprawling Hyades open cluster. The most famous open cluster in the sky, the Pleiades (M45), is positioned about 20 degrees to the west of Jupiter. On October 4, Jupiter reaches its stationary point and then afterwards its motion is retrograde.
As Jupiter is currently heading towards opposition in December, both the apparent magnitude and size of the planet are currently increasing. During October, Jupiter's brightness increases from magnitude –2.5 to –2.7 and the apparent size from 43 to 47 arc seconds.
Over the next few months Jupiter will dominate the evening sky. This is especially true for northern hemisphere observers; the planet appears high and bright, a sparkling jewel in the dark autumn and winter skies. It's not as good from southern latitudes as Jupiter is low down, but still unmistakable due to its brightness.
On October 5, the Moon will pass 0.9 degrees south of Jupiter. An occultation is visible from the Southern Australia and the Southern Ocean.
Saturn passes through superior conjunction on the far side of the Sun on October 25th. The planet is located in Virgo but for northern hemisphere observers is unobservable during October. From southern and tropical latitudes, Saturn may be glimpsed low down in the dusk sky during the first part of the month before the planet is quickly lost to the Suns glare.
Uranus (mag. 5.7) is located in Pisces just south of the "Great Square of Pegasus". The seventh planet from the Sun reached opposition at the tail end of last month and remains visible for most of the night. Uranus is located very close to star 44 Piscium, which at mag. 5.8 is almost equal in brightness. The planet for most of last month was positioned to the east of 44 Piscium before passing the star and now residing on the western side.
This is a good time to try and test how dark your skies are by attempting to spot Uranus with the naked eye. At magnitude 5.7, the planet is faintly visible to the naked eye but dark skies and good conditions are required. If your observing site is up to scratch, you should also be able to spot 44 Piscium.
Neptune (mag. 7.8) is located in the constellation of Aquarius and visible as soon as it gets dark. To be seen, the minimum requirements for this planet are a pair of binoculars or a small telescope. The most distant planet is located four degrees south of mag. 4.2 star Ancha (theta Aquarii) and remains observable until the early hours of the morning.
Solar System Data Table October 2012
|Date||Right Ascension||Declination||Mag.||Size||Illum. (%)||Distance (AU)||Constellation|
|Sun||5th Oct 2012||12h 44m 43.2s||-04d 48m 22.8s||-26.7||32.0'||100||1.000||Virgo|
|Sun||15th Oct 2012||13h 21m 30.8s||-08d 35m 08.5s||-26.8||32.1'||100||0.997||Virgo|
|Sun||25th Oct 2012||13h 59m 14.4s||-12d 09m 45.4s||-26.8||32.2'||100||0.994||Virgo|
|Mercury||5th Oct 2012||13h 47m 52.9s||-12d 02m 56.1s||-0.3||05.1"||89||1.314||Virgo|
|Mercury||15th Oct 2012||14h 41m 53.0s||-17d 48m 16.8s||-0.2||05.6"||80||1.205||Libra|
|Mercury||25th Oct 2012||15h 31m 08.4s||-21d 55m 32.7s||-0.2||06.4"||66||1.050||Libra|
|Venus||5th Oct 2012||10h 16m 36.2s||11d 11m 04.5s||-4.1||15.4"||72||1.083||Leo|
|Venus||15th Oct 2012||11h 01m 41.8s||07d 17m 39.2s||-4.0||14.5"||76||1.150||Leo|
|Venus||25th Oct 2012||11h 46m 31.2s||02d 58m 40.8s||-4.0||13.7"||79||1.214||Virgo|
|Mars||5th Oct 2012||15h 44m 11.5s||-20d 39m 36.6s||1.2||04.8"||93||1.958||Libra|
|Mars||15th Oct 2012||16h 14m 02.6s||-22d 09m 28.5s||1.2||04.7"||94||1.997||Scorpius|
|Mars||25th Oct 2012||16h 45m 01.4s||-23d 19m 48.5s||1.2||04.6"||95||2.033||Ophiuchus|
|Jupiter||5th Oct 2012||05h 01m 11.7s||21d 55m 13.0s||-2.6||43.6"||99||4.521||Taurus|
|Jupiter||15th Oct 2012||05h 00m 24.6s||21d 53m 45.0s||-2.6||44.9"||99||4.390||Taurus|
|Jupiter||25th Oct 2012||04h 58m 12.2s||21d 50m 22.2s||-2.7||46.1"||100||4.277||Taurus|
|Saturn||5th Oct 2012||13h 54m 27.6s||-09d 19m 57.4s||0.8||15.5"||100||10.716||Virgo|
|Saturn||15th Oct 2012||13h 58m 57.7s||-09d 45m 13.2s||0.8||15.5"||100||10.754||Virgo|
|Saturn||25th Oct 2012||14h 03m 33.4s||-10d 10m 18.5s||0.7||15.4"||100||10.768||Virgo|
|Uranus||5th Oct 2012||00h 24m 24.6s||01d 49m 16.5s||5.7||03.7"||100||19.068||Pisces|
|Uranus||15th Oct 2012||00h 22m 57.8s||01d 40m 03.7s||5.7||03.7"||100||19.102||Pisces|
|Uranus||25th Oct 2012||00h 21m 36.8s||01d 31m 32.4s||5.7||03.7"||100||19.166||Pisces|
|Neptune||5th Oct 2012||22h 12m 02.3s||-11d 47m 45.3s||7.8||02.3"||100||29.237||Aquarius|
|Neptune||15th Oct 2012||22h 11m 23.9s||-11d 51m 15.0s||7.9||02.3"||100||29.362||Aquarius|
|Neptune||25th Oct 2012||22h 10m 56.3s||-11d 53m 43.4s||7.9||02.3"||100||29.506||Aquarius|
Solar System Data Table November 2012
|Date||Right Ascension||Declination||Mag.||Size||Illum. (%)||Distance (AU)||Constellation|
|Sun||5th Nov 2012||14h 41m 24.1s||-15d 40m 40.6s||-26.8||32.3'||100||0.992||Libra|
|Sun||15th Nov 2012||15h 21m 48.1s||-18d 28m 57.1s||-26.8||32.3'||100||0.989||Libra|
|Sun||25th Nov 2012||16h 03m 35.3s||-20d 44m 41.6s||-26.8||32.4'||100||0.987||Scorpius|
|Mercury||5th Nov 2012||16h 05m 13.3s||-23d 33m 34.3s||0.2||08.1"||38||0.835||Scorpius|
|Mercury||15th Nov 2012||15h 46m 43.2s||-20d 25m 27.4s||4.0||09.9"||03||0.683||Libra|
|Mercury||25th Nov 2012||15h 06m 09.9s||-15d 05m 54.2s||0.9||08.7"||20||0.770||Libra|
|Venus||5th Nov 2012||12h 35m 15.8s||-01d 58m 27.3s||-4.0||13.0"||82||1.280||Virgo|
|Venus||15th Nov 2012||13h 20m 46.2s||-06d 35m 05.1s||-3.9||12.5"||84||1.336||Virgo|
|Venus||25th Nov 2012||14h 07m 21.9s||-11d 01m 08.7s||-3.9||12.0"||87||1.389||Virgo|
|Mars||5th Nov 2012||17h 19m 25.8s||-24d 10m 33.4s||1.2||04.5"||95||2.069||Ophiuchus|
|Mars||15th Nov 2012||17h 52m 13.3s||-24d 31m 55.4s||1.2||04.5"||96||2.100||Sagittarius|
|Mars||25th Nov 2012||18h 25m 31.4s||-24d 26m 49.4s||1.2||04.4"||96||2.130||Sagittarius|
|Jupiter||5th Nov 2012||04h 53m 28.3s||21d 43m 17.8s||-2.8||47.2"||100||4.176||Taurus|
|Jupiter||15th Nov 2012||04h 48m 45.9s||21d 35m 58.1s||-2.8||48.0"||100||4.111||Taurus|
|Jupiter||25th Nov 2012||04h 43m 18.8s||21d 27m 07.5s||-2.8||48.4"||100||4.075||Taurus|
|Saturn||5th Nov 2012||14h 07m 57.2s||-10d 33m 39.7s||0.8||15.5"||100||10.753||Virgo|
|Saturn||15th Nov 2012||14h 12m 30.6s||-10d 57m 08.2s||0.8||15.5"||100||10.714||Virgo|
|Saturn||25th Nov 2012||14h 16m 56.1s||-11d 19m 14.0s||0.8||15.6"||100||10.650||Virgo|
|Uranus||5th Nov 2012||00h 19m 37.2s||01d 18m 57.0s||5.8||03.7"||100||19.268||Pisces|
|Uranus||15th Nov 2012||00h 18m 39.3s||01d 13m 01.9s||5.8||03.6"||100||19.386||Pisces|
|Uranus||25th Nov 2012||00h 17m 56.6s||01d 08m 48.3s||5.8||03.6"||100||19.525||Pisces|
|Neptune||5th Nov 2012||22h 09m 57.3s||-11d 59m 06.2s||7.9||02.3"||100||28.990||Aquarius|
|Neptune||15th Nov 2012||22h 09m 55.6s||-11d 59m 08.7s||7.9||02.3"||100||30.139||Aquarius|
|Neptune||25th Nov 2012||22h 10m 07.1s||-11d 57m 58.2s||7.9||02.3"||100||30.332||Aquarius|
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