(Please note all times are ST unless otherwise stated and are based on an observing location of Belfast and covers the month of October)
At the start of the month, the Sun rises at 07:25 and sets at 19:00. By month's end, it rises at 07:25 UT and sets at 16:50 UT.
Mercury is not visible this month.
Venus is at inferior conjunction on the 26th and is not visible this month.
Mars is visible in the evening sky during the month. At the start of the month, it sets at 01:00. At month’s end, it sets at 23:35 UT and fades from mag -1.3 to mag -0.6 during the month. It is in Capricornus during the month.
Jupiter is an evening object this month in Libra. It sets at 20:15 at the start of the month and by month’s end, it sets at 17:30 UT. It fades from mag -1.7 to mag -1.6 during the month.
Saturn is an evening object in Sagittarius during the month. At the start of the month, it sets at 22:30 and by month’s end, it sets at 19:35 UT. It fades from mag +0.5 to mag +0.6 during the month.
Uranus is at opposition on the 24th and is an evening object in Aries during the month. At the start of the month, it rises at 19:35. By month’s end it rises during daylight hours. It maintains its brightness at mag +5.7 during the month and lies near to Omicron (ο) Piscium, mag +4.2.
Neptune is an evening object in Aquarius. At the start of the month, it sets at 05:05. By month’s end, it sets at 02:05 UT. It maintains its brightness at mag +7.8 during the month. It lies between Phi (φ) Aquarii, mag +4.2 and Lambda (λ) Aquarii, mag +3.7.
The last quarter moon is on the 2nd (10:45). The new moon is on the 9th (04:46) with the first quarter moon on the 16th (19:01). The full moon is on the 24th (17:45) with a 2nd last quarter moon on the 31st (16:40 UT).
1st am the 66% waning gibbous lies SE of Aldebaran (Alpha (α) Tauri, mag +0.9) at 00:00.
6th am the 12% waning crescent lies SE of Regulus (Alpha (α) Leonis, mag +1.4) at 04:00.
11th pm the 8% waxing crescent lies NW of Jupiter at 19:00.
12th pm the 15% waxing crescent lies NE of Jupiter and NW of Antares (Alpha (α) Scorpii mag +1.0) at 19:00.
14th pm the 31% waxing crescent lies W of Saturn at 19:00.
15th pm the 41% waxing crescent lies NE of Saturn at 19:00.
17th pm the 59% waxing gibbous lies W of Mars at 19:00.
18th pm the 68% waxing gibbous lies NE of Mars at 19:00.
20th pm the 84% waxing gibbous lies SW of Neptune at 19:00.
21st pm the 91% waxing gibbous lies SE of Neptune at 19:00.
23rd pm the 99% waxing gibbous lies W of Uranus at 19:00.
24th pm the full moon lies S of Uranus at 19:00.
26th pm the 95% waning gibbous lies NW of Aldebaran (Alpha (α) Tauri, mag +0.9) and S of M45 at 20:00.
27th pm the 88% waning gibbous lies E of Aldebaran (Alpha (α) Tauri, mag +0.9) at 21:00.
The best time to observe meteor showers is when the moon is below the horizon; otherwise its bright glare limits the number you will see especially the fainter ones. Below is a guide to this month's showers.
The Orionids peak in early evening on the 21st with a ZHR of 25. The radiant will be visible from midnight on the nights of the 20th/21st and 21st/22nd. Unfortunately, the show is ruined by a bright waxing gibbous moon in Aquarius on both nights which does not set until 03:45 and 05:00 on the 2 nights respectively.
There may be additional minor showers this month, details of which can be found in the below Information Sources and Links Section.
There are no bright asteroids at opposition this month.
Finder charts and further information about other fainter asteroids can be found in the below Information Sources and Links Section.
Comet 21P/Giacobini-Zinner peaked at mag +7 in September and is expected to fade in October. During the month, it is visible from 04:00 as it passes from Monoceros into Canis Major. It passes by M50 around the 7th and 8th and passes by Sirius (Alpha (α) Canis Majoris, mag -1.4) around the 15th.
Comet 38P/Stephan-Oterma is predicted to peak at mag +9 in November. It is currently mag +12 and moves from Orion into Gemini during the month. It is visible from 01:00 at both the start of the month and mid-month. It is visible from 22:00 UT by month’s end. It passes by Alhena (Gamma (γ) Geminorum, mag +1.9) around the 19th.
Finder charts and further information about the above and other fainter comets can be found in the below Information Sources and Links Section. Any of the above estimates are based on current information at the time of writing the guide and can be wrong - “Comets are like cats; they have tails, and they do precisely what they want”, David H Levy.
On the deep sky front this month, galaxies M81 and M82 can be observed in Ursa Major. In Lyra - M57 - The Ring Nebula can be observed and in Vulpecula - M27 - The Dumbbell Nebula can be found. In Andromeda, M31 - The Andromeda galaxy can be observed along with its satellite galaxies M32 and M110. In Perseus, there is the open cluster M34 and the excellent Double Cluster - NGC 869 and 884. In Triangulum, there is the galaxy M33. Auriga reappears with its three open clusters M36, M37 and M38 as does Taurus with the excellent Pleiades - M45 and the Hyades. Orion returns to our skies with M42 - The Great Orion Nebula along with Gemini with the open cluster M35.
Always keep an eye out for Aurorae. On the morning of the 28th at 2am, the clocks go back one hour and summer time ends. Other interesting naked eye phenomena to look out for include the Zodiacal Light and the Gegenschein. Both are caused by sunlight reflecting off dust particles which are present in the solar system.
The Zodiacal Light can be seen in the West after evening twilight has disappeared or in the East before the morning twilight. The best time of year to see the phenomenon is late-Feb to early-April in the evening sky and September/October in the morning sky - it's then that the ecliptic, along which the cone of the zodiacal light lies, is steepest in our skies. The Gegenschein can be seen in the area of the sky opposite the sun. To view either, you must get yourself to a very dark site to cut out the light pollution. When trying to observe either of these phenomena, it is best to do so when the moon is below the horizon. A new appendix has been added explaining some of the more technical terms used in the guide.
The ZHR or Zenithal Hourly Rate is the number of meteors an observer would see in one hour under a clear, dark sky with a limiting apparent magnitude of 6.5 and if the radiant of the shower were in the zenith. The rate that can effectively be seen is nearly always lower and decreases as the radiant is closer to the horizon. The Zenith is the overhead point in the sky.