The night skyin October 2018

posted 30 Sep 2018, 03:48 by Pete Collins   [ updated 30 Sep 2018, 12:41 ]
by Anne Holt

1st    Sunrise:   07.10      Sunset:  18.45
31st  Sunrise:   07.05      Sunset:  16.38

Astronomical darkness  1st:  20.42 to 05.14    31st:  18.36 to 05.08

New Moon:  9th at 04.46     Full Moon:  24th at 17.45
Lunar perigee:  19th at 22.31,   Lunar apogee: 17th at 19.18

The October full Moon is known as the Hunters' Moon because this was when the deer had fattened up enough that they could be hunted by the light of the autumn Moon, and caught in sufficient numbers to last through the winter.  Other names are the Dying Goose Moon, the Sanguine Moon and the Blood Moon.  This means that if we had a total Lunar eclipse in October it would be a Blood Blood Moon - but this won't happen until 2097. 

Highlights

We have reasonable amounts of astronomical darkness this month, 8 and a half hours on the night of 1st/2nd and 2 hours more on 31st/1st. However it still begins too late for our meetings to get the full benefit - 20.35 on 4th and 19.48 on 25th.   We have a return to Greenwich Mean Time in the early hours of Sunday 28th, when the clocks are put back one hour and we can begin 5 months of proper time.
Mars is still hanging on and the two outer ice giants are very well placed for telescopic observation. We have a few meteor showers, one fairly major, one minor which may turn out to be quite good, and several very minor ones. We also have the probability of some bright colourful fireballs towards the end of the month.

Constellations

The Summer Triangle, made up of Vega in Lyra, Deneb in Cygnus and Altair in Aquila, is losing its dominance in the night sky.  It is still visible during the first part of October high in the south west but by the end of the month all three constellations will have set by 4am. It's place in the southern sky is being taken by the Great Square of Pegasus, autumn's signature constellation.

The beautiful star cluster the Pleiades (also known as the Seven Sisters) followed by the rest of Taurus, will be visible by 11pm in early October and by 8pm (now back to GMT) at month end.

By the end of October Orion will be easily visible by midnight, with Sirius just above the eastern horizon at this time.

Perseus and Andromeda are still high in the sky for most of the night, making it a good time to look for M31, the Andromeda galaxy.   If you are at a very dark sky site, it should be visible to the naked eye, especially when using averted vision.

Cassiopeia is now high in the sky for most of the night, so the Plough, on the opposite side of the North Celestial Pole, is low in the north.

Planets

Mercury: in Virgo, Mag -0.9
An evening object in the first part of October but very difficult to see.  On 1st it sets 15 minutes after the Sun and is separated from it by only 7 degrees.  It moves into Libra on 16th, when it will have faded to mag -0.3 and be 2 degrees below the horizon at dusk. On 31st it sets at 17.05, almost half an hour after Sunset but is barely above the horizon as the sky darkens.

Venus:  in Virgo, mag -4.5
Also below the horizon during the hours of darkness for most of the month.  On 1st it sets just a couple of minutes after the Sun and is 2 degrees below the horizon as the sky begins to darken.  Reaches inferior conjuction on 26th and then becomes a morning object, rising 20 minutes before the Sun on 31st, but still below the horizon when the sky begins to brighten.

Mars:  in Capricorn,  mag -1.3
An evening object in October, a shadow of its June self but still quite prominent.  It fades further during the month but does get slightly higher in the sky.  On 1st it is 9 degrees above the eastern horizon as the daylight fades, culminating (reaching its highest point) 13 degrees in the south at 21.03, setting just before 1am.  The 68% lit Moon passes 3 degrees to the NE at about 19.00 on 18th.  On 31st it will have faded to mag -0.6, culminating at 19.02 at an altitude of 19 degrees in the south and setting at 23.30.

Jupiter:  in Libra,  mag -1.8
May be visible in the early part of the month, low in the west as the sky darkens, setting a few minutes after 20.00 on 1st.  On 11th it is close to the thin crescent Moon.  By month end it is only 3 degrees above the horizon at dusk, setting at 17.26, less than an hour after sunset.

Saturn:  in Sagittarius, mag 0.5
May be seen low in the SW after sunset.  On 1st it is 13 degrees above the horizon as the sky darkens at around 19.30, setting just before 22.30.  On 14th the crescent Moon passes 4.5 degrees west of the planet.  By 31st it will be visible for only a short time, 11 degrees above the southern horizon at 17.20, setting 2 and a quarter hours later.

Uranus:  in Aries,  mag 5.7
Visible for most of the night during October.  On 1st it is 22 degrees above the eastern horizon at 22.00, reaching 47 degrees in the south at 02.27.  It is at opposition on 24th, when it culminates at 00.53 and on the same night the full Moon passes 7 degrees ESE of the planet. On 31st it should be visible around 18.45, when it reaches 21 degrees in the east, culminating at 23.30 and setting at 06.29.  As it is now so well positioned and reasonably bright (for Uranus), it's a good time to try to find it with the naked eye -  if you are observing from a dark sky site.  From the light polluted Manchester sky binoculars, or even a small scope will be necessary.  A larger scope will show the small blue/green disc.

Neptune:  in Aquarius, mag 7.8
The second ice giant is also well placed in October. On 1st it will have reached 21 degrees by 21.00 and culminate at 23.29, at an altitude of 29 degrees above the southern horizon.  By 31st it reaches 21 degrees at around 18.00 and culminates at 20.29, setting at 2am.  As always a scope is needed to show its rich blue colour, though if you happen to have some decent binoculars with you while you're at a dark sky site looking at Uranus, you might just be lucky enough to see Neptune through them.

Minor Planets

With the exception of Ceres, which orbits in the asteroid belt, much closer than the rest, these are very faint and are out of reach of all but the most serious amateur astrophotographers.
Ceres:  in Virgo, mag 8.5 isn't visible for most of the month as it is in conjunction with the Sun on 8th, so too close to it to be seen. On 31st it rises 100 minutes before the Sun but is separated from it by only 14 degrees.

Haumea in Bootes and Makemake in Coma Berenices are also close to Solar conjunction.  Right at the end of October, Makemake at mag 17.1 might be a possible photographic target, reaching 27 degrees above the eastern horizon at around 3am.

Pluto, in Sagittarius, mag 14.7 is also very low, maximum altitude 14 degrees and setting before midnight in early October and at 20.40 on 31st.

Eris, appropriately named after the goddess of strife and discord, is in Cetus, While very faint at mag 18.8 it is in a much better position for astrophotographers.  On 1st it culminates at 02.14 at 34 degrees above the southern horizon.  It's at opposition on 16th, reaching its highest point at 01.15 and on 31st it is in the same position at 23.11.

For more details and exact positions of these at any time, see:

Meteors

One reasonably major shower in October.
Orionids, active October 2nd to November 7th, peak on the night of 21st/22nd, ZHR 20+.  This shower often also has several smaller peaks on the days before and after the maximum. Sometimes a ZHR of up to 50 has been observed,  They are fast moving meteors, often leaving trails.  The parent comet is the best known one of all - 1P/Halley. On the morning of 22nd the almost full moon sets at 04.42 and astro darkness ends at 05.51, giving just over an hour of optimum conditions.

Middling shower
Draconids, aka Giacobinids, active 6th to 10th, peak 9th, ZHR 10.  This shower, like most others is best seen after midnight.  It is said to sometimes show much higher rates when its parent comet, 21P/Giacobini-Zinner, is close to perihelion - as it was in September this year, so you never know!   These are exceptionally slow moving meteors.  New Moon is on 9th, so no interference.

Minor showers.
Camelopardalids:  active 5th to 6th, peak in th early hours of 6th, ZHR 1 - in other words you might be lucky enough to see a couple of meteors.  But maybe not, there hasn't been much activity in the last few years.  However some sources give a ZHR of 5 and say that there could be an outburst on 6th, soon after 3am - just as the Moon is rising.

Southern Taurids:  active late September to early November, peak 10th, ZHR 5.  There may also be minor peaks at any time.  This shower of slow moving meteors is best known for including colourful fireballs.  The crescent Moon sets at 19.28 on 10th.

Northern Taurids:  don't peak until November 12th but can be seen from around 20th October.  These are very similar to the Southern Taurids, it's thought that they were originally one shower which split into 2 streams many thousands of years ago.  As always, poor Jupiter gets the blame when something like this has happened.   The parent comet of both streams is now defunct, it broke into several pieces one of which became Comet Encke.   Several fireballs are often seen in late October when both Taurid showers are active.

Epsilon Geminids: active 14th to 17th, peak 18th, ZHR 3,   Meteors from this shower are often confused with Orionids as they are active around the same time, look similar and have radiants which are not too far apart.  But unless you're a serious meteor observer, I very much doubt that you care!

Leonids Minorids: peak 28th,  ZHR 2

Alpha Aurigids:  active 10th to 18th, peak 11th,  ZHR 2

Comets

21P/Giacobini-Zinner, in Monoceros, mag around 7.6.  The parent comet of October's Draconids is now past its best, heading southwards. On 1st it rises at 01.19 and reaches an altitude of 32 degrees in the south by 04.15. It moves into Canis Major on 11th, passing about 6 degrees east of Sirius on the morning of 13th.  By month end it wll be very difficult to find, down to mag 9.6 and only 8 degrees above the horizon as the sky brightens.

38P/Stepha-Oterma, in Orion, mag 9.7.  Fainter than Giacobini-Zinner but much better placed - and improving.  Starts the month a few degrees north of Betelgeuse, rising soon after 23.30 and reaching 47 degrees in the south while the sky is still dark.  It moves into Gemini on 13th,reaching 50 degrees before dawn.  It then moves N eastwards through the centre of the constellation, on 31st it rises at 20.45 and culminates, 54 degrees above the southern horizon, just before 5am, slightly brighter at mag 9.0.

46P/Wirtanen.  Still very low, and faint at mag 10, but be patient, in November it starts to move north and should have brightened considerably.  On 1st it culminates at 02.20 but only reaches 9 degrees above the horizon, by 31st it's even lower, maximum altitude only 2 degrees, but a little brighter at mag 7.4.
Some sources now say that it will not get as bright as originally predicted but others are still saying that it should be a naked eye object in December, maybe mag 3,  This comet was originally intended to be the target for ESA's Rosetta mission but it wasn't ready in time for the launch window and was sent to Churyumov-Gerasimenko instead.   Pity, it would have made life so much easier for anyone wanting to talk about it.

More comet info can be found in the websites mentioned earlier and also  www.cometwatch.co.uk




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