OBSERVING GUIDE
(Please note all times are UT unless otherwise stated and are based on an observing location of Belfast and covers the month of December)
The Sun
At the start of the month, the Sun rises at 08:25 and sets at 16:00. By month’s end, it rises at 08:45 and sets at 16:05.
The Planets
Conjunction
29th pm Mercury lies 1.4 degrees to the NW of Venus just after sunset (16:00), a VERY flat SW horizon needed.
Regular Stuff
Mercury is at greatest eastern elongation on the 21st and is visible in the post sunset sky from the 2nd week of the month. It will be very close to the horizon as a heads up. By month’s end it sets at 17:15 and is mag +1.1 in Sagittarius.
Venus becomes visible in the post sunset sky this month but again like Mercury it will be very close to the horizon. By month’s end it sets at 17:20 and is mag -3.8 in Sagittarius.
Mars is at opposition on the 8th and is visible in the evening sky during the month in Taurus. It rises at 16:10 at the start of the month and during daylight hours by month’s end. It fades during the month from mag -1.8 to mag -1.2.
Jupiter is at eastern quadrature on the 22nd and is visible in the evening sky during the month in Pisces. It sets at 01:30 at the start of the month and at 23:40 by month’s end. It fades during the month from mag -2.4 to mag -2.2.
Saturn is visible in the evening sky during the month in Capricornus. It sets at 21:30 at the start of the month and at 19:50 by month’s end. It maintains its brightness at mag +0.8 during the month.
Uranus is visible in the evening sky during the month in Aries. It lies W of Botein (Delta (δ) Arietis, mag +4.3). It sets at 06:10 at the start of the month and at 04:10 by month’s end. It fades from mag +5.6 to mag +5.7 during the month.
Neptune is at eastern quadrature on the 14th and is visible in the evening sky during the month in Aquarius. It sets at 00:55 at the start of the month and at 22:50 by month’s end. It maintains its brightness at mag +7.9 during the month. It lies S of the Circlet Asterism.
The Moon
The full moon is on the 8th (04:08) with the last quarter moon on the 16th (08:56). The new moon is on the 23rd (10:17). The first quarter moon is on the 30th (01:20).
Occultations
5th pm the 94% waxing gibbous will occult Uranus. The planet will disappear behind the moon from around 16:50 and reappear from around 17:10.
8th am the full moon will occult Mars. The planet will disappear behind the moon from around 04:40 and reappear from around 05:40.
Regular Stuff
1st pm the 62% waxing gibbous lies SW of Jupiter and SE of Neptune at 18:00.
2nd pm the 73% waxing gibbous lies SE of Jupiter at 18:00.
5th pm the 94% waxing gibbous lies SE of Uranus at 18:00.
6th pm the 98% waxing gibbous lies SW of M45 – The Pleiades at 18:00.
7th pm the near full moon lies NE of Aldebaran (Alpha (α) Tauri, mag +0.9) and NW of Mars at 18:00.
8th pm the just past full moon lies SE of Mars at 18:00.
13th pm the 72% waning gibbous lies N of Regulus (Alpha (α) Leonis, mag +1.4) at 23:00.
14th pm the 63% waning gibbous lies SE of Regulus (Alpha (α) Leonis, mag +1.4) at 23:00.
18th am the 32% waning crescent lies N of Spica (Alpha (α) Virginis, mag +0.9) at 04:00.
19th am the 22% waning crescent lies SE of Spica (Alpha (α) Virginis, mag +0.9) at 04:00.
26th pm the 16% waxing crescent lies SE of Saturn at 18:00.
28th pm the 36% waxing crescent lies S of Neptune at 18:00.
29th pm the 47% waxing crescent lies SE of Jupiter at 18:00.
Meteors
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 Geminids peak at 13:00 on the 14th with a ZHR of 150. The radiant is visible from 18:00 on the evenings of the 13th and 14th. Unfortunately there is a bright waning gibbous moon around to partially spoil the show. There is a pre moonrise window for observing on both nights with moonrise at 21:00 on the 13th and 22:15 on the 14th.
There may be additional minor showers this month, details of which can be found in the below Information Sources and Links Section. 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.
Asteroids
Asteroid (349) Dembowska is at opposition on the evening of the 1st in Taurus and is mag +9.7. It is visible as soon as darkness falls on the 1st.
Finder charts and further information about other fainter asteroids can be found in the below Information Sources and Links Section.
Comets
Comet C/2022 E3 (ZTF) is currently mag +9 and is predicted to peak at mag +5 in February. During the month, it moves from Serpens to Corona Borealis. During the month it is visible in both in the morning and evening skies. At the start of the month, it rises at 03:00 and sets at 20:00. By mid-month, it rises at 02:00 and sets at 19:00. By month’s end, it rises at Midnight and sets at 19:00.
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. “If you want to have a safe gamble, bet on a horse – not a comet”, Dr Fred Whipple.
Deep Sky
On the deep sky front this month, galaxies M81 and M82 can be observed in Ursa Major. 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. In Auriga there are three open clusters M36, M37 and M38 and also M35 in Gemini. Taurus has the excellent Pleiades – M45, the Hyades and also M1 – The Crab Nebula. Orion returns to our skies with M42 – The Great Orion Nebula and also Cancer with M44 – The Beehive Cluster.
General Notes
Always keep an eye out for Aurorae. The winter solstice is on the 21st which sees the shortest day of the year and after this date the nights shorten and the days lengthen. This also sees the beginning of winter. 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.
Clear Skies
Neill McKeown
Information Sources and Links
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.
