Astro Calendar - October

Posted 30 Sep 2014

Lots of activity in the night sky for October! 

Pegasus flies high in the S as Taurus and the Pleiades climb in the E and the Summer Triangle topples into the W. As they do every autumn, the Plough is turning counter clockwise below Polaris in the N as the stars of Cepheus and Cassiopeia glimmer overhead in the Milky Way.

Saturn, mag 0.6 in Libra, is very low in the SW at nightfall though we lose it in the twilight by mid-month. The Moon occults Saturn low in Britain’s daytime sky at about 17:00 BST on the 25th October.

Mars, mag 0.8 and further to the SSW at nightfall, lies 4° above Antares in Scorpius at present but tracks 22° eastwards into Sagittarius. Meanwhile, the dim telescopic Comet Siding Spring moves northwards to sweep some 135,000km from Mars on the 19th – the closest known approach of any comet to Mars or the Earth.

The planets Neptune and Uranus, are binocular objects at mag 7.8 in Aquarius and 5.7 in Pisces respectively. Pisces lies S and E of the Square of Pegasus while Uranus lies alongside the Moon when it stands opposite the Sun at a distance of 2,845 million km on the 7th. It is one of the gas giant planets, whose equatorial diameter is actually 51,118km but only 3.7 arcsec as seen through a telescope.

Jupiter rises in the ENE by 02:10 BST (01:10 GMT) on the 1st and by 23:30 GMT on the 31st, climbing to prominence between the SE and S by dawn. It improves slightly from mag -1.9 to -2.0 as it slips from Cancer to Leo, drawing to within 10° of Regulus. Catch it above the Moon on the 18th when it shows a 35 arcsec disc through a telescope.

Venus rises in the E just before dawn but is soon lost from view as it moves towards the Sun’s far side. Mercury becomes a morning star in the E after the 22nd and shines at mag -0.4 when some 7° high at 06:00 on the 31st.

Neither of October’s two eclipses are visible from Europe. The Moon passes through the N half of the Earth’s shadow in a total lunar eclipse on the 8th. It enters the outer penumbral shadow at 08:16 GMT but little darkening will be seen until it nears the central dark umbra which it begins to enter at 09:15.

The Moon is totally eclipsed within the umbra from 10:25 until 11:24 as it sets for observers in the E of the USA. During these 59 minutes, expect the Moon to display a dark reddish face, with its S parts darker since they are closer to the shadow’s core. The umbra is left behind at 12:34 and the eclipse ends when the disc is free of the penumbra at 13:34. Note that all these times are GMT so they will need to be converted for local time zones.

The second of the month’s eclipses, a partial solar eclipse on the 23rd, is visible from most of N America and the NE Pacific. At its best, over N Canada, more than 80% of the Sun’s diameter is hidden by the Moon but this dips to 35-65% for watchers in the USA who see mid-eclipse between 22:00 and 23:00 GMT. The Sun sets during the eclipse for the E half of the USA and Canada.

October Diary

1st     21h     First quarter

7th    22h     Uranus at opposition

8th    12h     Full moon and total lunar eclipse

15th 20h     Last quarter

16th 22h     Mercury in inferior conjunction

18th 04h     Moon 5° S of Jupiter

19th 04h     Moon 5° S of Regulus

23rd 23h     New moon and partial solar eclipse

25th 08h     Venus in superior conjunction; 17h Saturn occulted by Moon

26th 02h BST = 01h GMT End of Summer Time

by Simon Byland