Deep Southern Skies - October 2015
Welcome to a monthly description of our beautiful northern NSW night sky.
Occultation* of Venus by the Moon.
Jupiter, Mars and Venus take turns being close to each other.
*an occultation is when a body passes in front of a more distant astronomical object.
5th Last Quarter.
9th 7 am Occultation of Venus by the Moon. See Venus section.
11th Moon at apogee (furthest from Earth at 406,388 km).
13th New Moon.
21st First Quarter.
26th Moon at perigee (closest to Earth at 358,463 km).
27th Full Moon.
Mercury begins the month between the Earth and the Sun (inferior conjunction) and then moves into the eastern dawn sky. The planet reaches its greatest elongation west (18°) of the Sun on the 16th but barely visible above the horizon before sunrise.
Venus has a busy month in the eastern dawn sky. The occultation with the Moon occurs on the 9th, disappearing at 04:21 and reappearing at 05:47. This is a good opportunity to locate and observe Venus during the day as it does not stray more than a couple of de-grees from the Moon up until noon. From the 22nd till month end Venus, Mars and Jupiter can be found within 5° of each other in the eastern morning sky in Leo, with Venus coming within 1° of Jupiter on the 26th. This is also the date of Venus’ greatest elongation west of the Sun (46°).
Mars is visible in the eastern dawn sky together with Venus and Jupiter in Leo. On the 10th, the 27-day old waning crescent Moon appears to the south (right) of Mars with Jupiter below. Mars and Jupiter have an intimate encounter on the 18th when they are just 0.4° apart. Mars and Jupiter separate and the faster moving Venus glides past the gas giant and catches up with the Red Planet - at month end they will be 2° apart and even closer in early November.
Jupiter, in Leo, rises before dawn in the eastern sky and the following events can be ob-served close to the horizon in a dark sky. On the 10th, the waning crescent Moon, Jupiter and Mars form a triangle. On the 18th, Jupiter and Mars are a close 0.4° apart. Mars drops away from Jupiter and Venus comes closer un till they are 1° apart on the 26th - the three planets remain close for the rest of the month.
Saturn is visible in the early western evening sky in Libra for the first half of the month then crosses back into Scorpius for the remainder. On the 16th, the slender crescent of the 3-day old waxing crescent Moon appears below the planet. At the end of October, the ringed planet will be within 1° of the brilliant double stars Beta and Nu Scorpii.
Uranus is at opposition on the 12th in the early evening eastern sky in Pisces and visible the entire night. At magnitude 5.7, those with keen eyesight and dark skies should have no trouble seeing this outer world. Through a telescope, though devoid of detail, its blue/green colour should be unmistakable. On the 26th at dusk, the ice giant will be less than 0.3° from the limb of the 13-day old waxing gibbous Moon.
Neptune in Aquarius, transits the meridian (is due north) around 9 pm mid-month.
DWARF PLANETS AND SMALL SOLAR SYSTEM BODIES
Pluto, in Sagittarius, transits the meridian (due north) around 6 pm mid-month.
Comet 10P/Tempel 2. As October opens it shines at 11th magnitude in Ophiuchus, setting late in the evening. By the end of the month it brightens to 10th magnitude as it moves into Sagittarius but observing will be hindered by the waxing Moon.
Comet 22P/Kopff, setting in the mid-evening, moves from Libra into Scorpius before spending the later half of October in Ophiuchus and is predicted to be about 11.5 magni-tude.
Comet C/2013 US10 (Catalina) is in Centaurus at the beginning of October, setting around 10 pm. It is predicted to shine at 7th magnitude initially and brighten to 6th magnitude by late October, by which time it will be hard to seeing in the evening twilight sky.
IMAGE FOR OCTOBER - GLOBULAR CLUSTER 47 TUCANAE
47 Tucanae is a jewel of the southern sky, possibly the finest globular cluster in the entire sky. Visible to the naked eye alongside the Small Magellanic Cloud in the constellation of the Toucan, this massive ball of stars is 16,000 light years away from our solar system. The concentrated light of one million stars packed into a volume of space 120 light-years across makes the heart of 47 Tucanae a very crowded place. If the Solar System were transported to the centre of the cluster, the integrated starlight would fill the sky with stars and there would be no night.
Astronomy 2015 Australia. Quasar Publishing 2014.
The SkyX Professional Edition planetarium software.
47 Tucanae image, Alan Brockman, Sep 2015 credit.