January 2023 Observing Guide

Hi all,

PLEASE NOTE THE BELOW SUMMARY AND GUIDE IS FOR AN APPROXIMATE LATITUDE OF 55 DEGREES NORTH 

One naked eye event to look out for in January. On the evening of the 22nd, Venus lies below left of Saturn after sunset. Start looking South West from 5pm and the two planets will then be visible for around 90 minutes before they set. The gap between them will be 20 arcminutes which is less than the width of the full moon when observed from Earth. On the following evening, they are joined by a 5% waxing crescent moon which will lie to the left of the two planets. 

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 January)

The Sun

At the start of the month, the Sun rises at 08:45 and sets at 16:05. By month's end, it rises at 08:15 and sets at 17:00.

The Planets

Conjunction 

22nd pm Venus lies 20 arcminutes to the SE of Saturn after sunset. The two planets are visible from 17:00 for around 90 minutes.

Regular Stuff 

Mercury is at inferior conjunction on the 7th and at greatest western elongation on the 30th. It is visible in the early evening sky at the start of the month, setting at 17:10 roughly 1 hour after sunset. It will be mag +1.6 in Sagittarius. It becomes visible in the morning sky in the 2nd half of the month and at month’s end, it rises at 07:10, roughly 1 hour before sunrise. It will be mag +0.0 in Sagittarius.

Venus is visible in the evening sky this month, moving from Sagittarius to Aquarius. At the start of the month, it sets at 17:20 and by month’s end it sets at 19:05. It maintains its brightness at mag -3.8 during the month.

Mars is visible in the evening sky during the month in Taurus. It sets at 06:45 at the start of the month and at 04:50 by month’s end. It fades during the month from mag -1.2 to mag -0.3.

Jupiter is visible in the evening sky during the month in Pisces. It sets at 23:40 at the start of the month and at 22:10 by month’s end. It fades during the month from mag -2.2 to mag -2.0. 

Saturn is visible in the evening sky during the month in Capricornus. It sets at 19:45 at the start of the month and at 18:10 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 SW of Botein (Delta (δ) Arietis, mag +4.3). It sets at 04:05 at the start of the month and at 02:05 by month’s end. It maintains its brightness at mag +5.7 during the month.

Neptune is visible in the evening sky during the month in Aquarius. It sets at 22:50 at the start of the month and at 20:55 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 6th (23:08) with the last quarter moon on the 15th (02:10). The new moon is on the 21st (20:53). The first quarter moon is on the 28th (15:19). 

Occultation 

1st pm the 78% waxing gibbous will occult Uranus. The planet will disappear behind the moon from around 22:15 and reappear from around 23:00.

Regular Stuff 

2nd pm the 85% waxing gibbous lies SW of M45 – The Pleiades at 18:00.
3rd pm the 91% waxing gibbous lies N of Aldebaran (Alpha (α) Tauri, mag +0.9) and SW of Mars and SE of M45 – The Pleiades at 18:00.
4th pm the 96% waxing gibbous lies E of Aldebaran (Alpha (α) Tauri, mag +0.9) and SE of Mars at 18:00.
9th pm the 92% waning gibbous lies N of Regulus (Alpha (α) Leonis, mag +1.4) at 21:00.
10th pm the 86% waning gibbous lies SE of Regulus (Alpha (α) Leonis, mag +1.4) at 21:00.
15th am the last quarter moon lies E of Spica (Alpha (α) Virginis, mag +1.0) at 02:00.
18th am the 18% waning crescent lies NW of Antares (Alpha (α) Scorpii, mag +1.0) at 07:00.
23rd pm the 5% waxing crescent lies E of Saturn and Venus at 18:00.
25th pm the 20% waxing crescent lies SW of Jupiter and NE of Neptune at 18:00.
26th pm the 30% waxing crescent lies NE of Jupiter at 18:00.
28th pm the 51% waxing gibbous lies SW of Uranus at 18:00.
29th pm the 61% waxing gibbous lies NE of Uranus and SW of M45 – The Pleiades at 18:00.
30th pm the 71% waxing gibbous lies NW of Aldebaran (Alpha (α) Tauri, mag +0.9) and W of Mars and SE of M45 – The Pleiades at 18:00.
31st pm the 79% waxing gibbous lies NE of Aldebaran (Alpha (α) Tauri, mag +0.9) and SE of Mars 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 Quadrantids peak at 04:00 on the morning of the 4th with a ZHR of 110. However the low position of the radiant makes a much lower ZHR more realistic. The radiant is roughly where the constellations Boötes, Draco and Hercules meet low in the North and is circumpolar. The meteors are of a medium speed – 42 km/s. The shower is named after a now defunct constellation Quadrans Mualis which lay between Boötes and Draco. Not a good year for the shower with a 91% waxing gibbous moon up most of the night of the 3rd/4th in Taurus and only setting at 05:45. 

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 (2) Pallas is at opposition on the evening of the 8th in Canis Major and is mag +7.7. It is visible from 22:00 on the 8th. 

Asteroid (6) Hebe is at opposition on the evening of the 26th in Cancer and is mag +8.8. It is visible from 18:00 on the 26th. 

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 +8 and MAY peak at mag +5 at the start of February. During the month, it moves from Corona Borealis to Bootes to Draco to Ursa Minor to Camelopardalis. At the start of the month, it is visible in both the evening and morning skies when it rises at Midnight and sets at 19:00. By mid-month, it is circumpolar and will be above the horizon all night.

On the evenings of the 8th and 9th, it lies near Kappa (κ) Coronae Borealis, mag +4.8. On the evening of the 22nd, it lies to the E of M102. On the evening of the 23rd, it lies to the SW of Edasich (Iota (ι) Draconis, mag +3.3). On the evening of the 27th, it lies to the SW of Kochab (Beta (β) Ursa Minoris, mag +2.0). On the evenings of the 29th – 31st, it passes to the W of the Pole Star - Polaris (Alpha (α) Ursa Minoris, mag +2.0). 

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. 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

Sky at Night Magazine Observing Guide – All Rounder
Stardust Magazine – All Rounder
Philip's Stargazing 2023 – All Rounder
Collins 2023 Guide to the Night Sky – All Rounder
Yearbook of Astronomy 2023 – All Rounder
2023 calendar of annual Astronomical events by John Flannery – All Rounder
Sky Safari App – All Rounder
Stellarium App – All Rounder
in-the-sky.org/ – All Rounder
www.nightskyhunter.com/ - All Rounder
www.heavens-above.com – All Rounder
www.timeanddate.com/astronomy/ - All Rounder
www.irishastronomy.org  - Irish Federation of Astronomy Societies Website and Calendar – All Rounder
irishastro.org.uk/- Irish Astronomical Association website – All Rounder
www.eaas.co.uk  - Northern Ireland Amateur Astronomy Society – All Rounder
eco.mtk.nao.ac.jp/cgi-bin/koyomi/cande/phenomena_en.cgi – Sun/Planets/Moon Only
cal2023.pdf (imo.net) - International Meteor Organisation 2023 Meteor Shower Calendar
www.cobs.si – Comet Observation Database
www.aerith.net – Comets Only
www.ast.cam.ac.uk/%7Ejds/ - Comets Only
astro.vanbuitenen.nl – Comets Only
theskylive.com/ - Comets/Asteroids
messier.seds.org/ - The Messier Catalogue website – Deep Sky Only
www.spaceweather.com – Aurorae Forecasts/Naked Eye Atmospherics
astro.ukho.gov.uk/eclbin/query_eo.cgi - Eclipses 

Appendix

The radiant is the point in the sky, from which (to a planetary observer) meteors appear to originate, i.e. the Perseids, for example, are meteors which appear to come from a point within the constellation of Perseus. When the radiant is quoted as "circumpolar", it is never below the horizon and visible all night, otherwise the times quoted are when the constellation in which the radiant lies rises above the horizon in the East.

A fireball is defined by the International Astronomical Union as a meteor brighter than any of the planets, i.e. magnitude -4 or brighter. The International Meteor Organisation alternatively defines it as a meteor which would have a magnitude of -3 or brighter at the zenith.

The full moon’s width when viewed from the Earth is 30 arc minutes or ½ a degree. This should give an idea for judging any distances quoted in the guide.

An asterism is a collection of stars seen in Earth's sky which form simple patterns which are easy to identify, i.e. the Big Dipper. They can be formed from stars within the same constellation or by stars from more than one constellation. Like the constellations, they are a line of sight phenomenon and the stars whilst visible in the same general direction, are not physically related and are often at significantly different distances from Earth. 

A conjunction is when two objects appear to be close to each other in the sky according to the perspective of the observer. 

Mag is short for magnitude which is the measure of an object's brightness. The smaller the number, the brighter the object. The brightest object in the sky is the Sun at mag -26, the full moon is mag -12 and Venus the brightest planet is mag -4. The brightest stars are mag -1. If there is a 1 mag difference between two objects - there is a difference in brightness of a factor of 2.5 between the two objects. For example the full moon is eight magnitudes brighter than Venus on average which means it is 1,526 times brighter than Venus. Objects down to mag +6 can be seen with the naked eye under very dark skies. 

Local time is always quoted in the guide and this means for November - February - universal time (UT)/GMT is used and for April to September - daylight savings time (DST, = GMT+1). For the months of March and October when the clocks go forward/back respectively, both times will be used and attention should be paid to any times at the end of these months for that change.

Deep Sky Objects such as galaxies, nebulae and star clusters are classified in catalogues such as the Messier catalogue for objects like M44 - M for Messier. Another example of a catalogue would the New General catalogue whose objects have the prefix NGC. There are links for websites to both catalogues in the section above.

Perihelion is the point in the orbit of a planet, asteroid or comet where it is at the nearest point in its orbit to the sun. It is the opposite of Aphelion, which is when the object is at the farthest point in its orbit from the sun. For the earth, the comparative terms used are perigee and apogee and for the moon, pericynthion and apocynthion are sometimes used. The Planets

From Earth - Mercury and Venus are the inner planets in the solar system and Mars, Jupiter, Saturn, Uranus and Neptune are the outer planets. Below is a short guide as to how both the inner and outer planets move around the sun. The above pictorial guide should hopefully help in this.

The Inner Planets

These are best seen when at Greatest Eastern/Western elongation and are not visible when at either Inferior/Superior conjunction. Greatest Eastern elongation is when the inner planet is at its furthest point east from the sun as seen from Earth and visible in the evening sky in the West after sunset, Western elongation is when it's at its furthest point west from the sun as seen from Earth and visible in the morning sky in the East before sunrise. Inferior conjunction occurs when the inner planet is between the Sun and the Earth. Superior conjunction occurs when the inner planet is on the other side of the Sun as seen from Earth.

From our Northerly latitudes, the ecliptic, along which the planets move, lies at a very shallow angle to the horizon after sunset in the autumn and before sunrise in the spring. This means that any of the planets will be difficult to see when fairly close to the Sun in the evening sky in the autumn or in the morning sky in the spring. In particular, Mercury is more or less invisible from here when at Eastern elongation in the autumn or at Western elongation in the spring, because it lies so close to the horizon and is never above the horizon except in daylight or bright twilight.

The normal cycle for an inner planet is Superior Conjunction - Greatest Eastern Elongation - Inferior Conjunction - Greatest Western Elongation - Superior Conjunction. After superior conjunction, the planet moves away from the Sun as seen from Earth and becomes visible in the evening sky after a period of time. It then moves past the point of Greatest Eastern Elongation and moves back towards the Sun as seen from Earth until a point when it is not visible and at Inferior Conjunction. After this the planet appears in the morning sky for a time, before again slipping into the Sun's glare as seen from Earth. The duration of this cycle will depend on the planet's closeness to the Sun, i.e. Mercury completes the above cycle in around 4 months.

The Outer Planets

These are best seen when at opposition and are not visible when at conjunction. Opposition occurs when the earth is between the sun and the outer planet. It is the best time to observe them because the planet is visible all through the night and it is due south and at its highest at about midnight. The planet is also at its closest point in its orbit to Earth - making it appear brighter. Conjunction occurs when the outer planet is on the other side of the Sun as seen from Earth.

If the planet is at or near it furthest point south along the ecliptic, then it won't get very high in the sky even at opposition - just as the Sun never gets high in the sky in midwinter. This happens when opposition occurs near midsummer when the planet is opposite the Sun in the sky and in midsummer the Sun is high, so the planet will be low. The opposite of course applies in winter.

The normal cycle for an outer planet is Conjunction - Western Quadrature - Opposition - Eastern Quadrature - Conjunction. After conjunction, the planet moves away from the Sun as seen from Earth and becomes visible again. The planet from this point on rises earlier and earlier in the morning sky and eventually becomes visible in the evening sky. At Western Quadrature it is at its highest at sunrise and by opposition it is in the same position by midnight. By Eastern Quadrature, it is past its best and is at its highest at sunset, meaning it is rising in daytime and setting earlier and earlier until a point when it sets too close to the Sun as seen from Earth and is no longer visible. The duration of this cycle will depend on the planet's closeness to the Sun, i.e. Jupiter completes the above cycle in around 13-14 months.