Dundee Astro - Planetary Notes

Venus itself is a morning object throughout the period and is also slowly falling back towards the Sun. It rises around 03.45UT early in October, very bright at -3.9 magnitude, and makes 20 degrees of elevation in the east before the Sun breaks the horizon; this falls to less than 15 degrees late in October when it will rise in astronomical twilight, around 05.20UT. Venus remains a bright and obvious morning object in November but losing out more and more to morning twilight over the month As mentioned, on the mornings of 24 to 26 November it is very close to Mercury with Mercury passing from north to south over much brighter Venus in this period; look for them low in the south-east in civil twilight from around 06.45UT.
Mars spends the period very low in the western evening sky, slowly drawing closer to solar conjunction. For most UK observers it will be lost to evening twilight throughout, but the further south you are, the better your chance of catching its +1.6 magnitude red-spark, low in the south-west, as the sky darkens, especially in very early October. It does sit directly above Mercury for a couple of days either side of 20 October and
meets Mercury again around 12 November but both conjunctions will be hard to see unless sought out in daylight.

Jupiter is an excellent late-night to early morning object in this period, very obvious below Castor and Pollux in Gemini. It will rise in the north-east around 22.50UT early in October, 21.00UT mid-period and 19.00UT late in November. Initially Jupiter will gain 50 degrees of elevation in the south-east by morning twilight but by mid-period will transit in full darkness, that is it will be due-south, at nearly 60 degrees high, around
05.00UT. Late in November Jupiter transit, at a similarly magnificent altitude, will occur around 03.05UT. Jupiter will brighten slightly from -2.2 to -2.5 magnitude and grow from 37 to 44 arcseconds (37-44”) in apparent size across the equator making very detailed viewing highly likely on steady nights.

Before you view Jupiter you should seek out Saturn. It starts the period just past opposition so is increasingly accessible in the earlier evening hours, shining at +0.7 magnitude, below the great square of Pegasus. The span of the rings falls from 44” to 41” in the period but this still offers a large and detailed target to observe. South transit times are around 23.10UT in early October, 21.00UT mid-period and 19.05UT in late
November. In each case Saturn will gain over 30 degrees of elevation in the south for all but the most northern parts of the UK. This year we are seeing the ring system nearly edge on. This means there will be a number of moon and shadow transits visible, though most moons are too small to be readily visible. The exception is Titan which can be very noticeable. A reasonably accessible Titan transit starts around 01.30UT on 06 October when Saturn sits 25 degrees up in the south-west. Better is a transit starting at 22.47UT on 21 October with Saturn sitting more than 30 degrees high in the south. That transit finishes around 04.30UT the next morning but, from the UK, Saturn will have already set by then. On 22 November another such transit starts around 18.58UT then slowly crosses the disk, leaving it around 00.55UT; on this occasion Titan passes just north of the shadow cast by the ring system onto the cloud tops of the planet and all such transits in the period cross the northern hemisphere. The shadow cast by Titan itself passes just north of Saturn so, sadly, will not be visible in this period.

Neptune keeps close company with Saturn throughout the period sitting slightly higher and a little back along the line of the ecliptic from the ringed planet, which therefore acts a good starting point to seek out this tiny ice-giant. In early October the separation is 3 degrees with south transit around 23.20UT. Mid period this has stretched to 4 degrees with transit around 21.15UT and by late November transit is around 19.20UT with Neptune slightly more than 4 degrees above and behind Saturn. At +7.7 magnitude and 2.3” in size, you will need good binoculars or a telescope to find this one.

Uranus reaches opposition on 21 November, so is observable for most of the hours of darkness on any clear night in this period. Its +5.6 magnitude, 3.2” disk sits some 4.5 degrees directly below M45 (The Pleiades cluster) when at south transit. This occurs around 03.15UT in early October. 01.10UT in early November and 23.50UT on opposition night. It is best seen around the time of south-transit when it will be around 57 degrees high for most of the UK. Use binoculars to scan slightly down from the magnificent Pleiades and look for a blue-green ‘star’. With a telescope, add power to see its 3.8” disk shining at +5.6 magnitude