OBSERVING GUIDE January 2024

The Sun
At the start of the month, the Sun rises at 08:50 and sets at 16:05. By month's end, it rises at
08:15 and sets at 16:55.

The Planets

Mercury is at greatest western elongation on the 12th. It is visible very low in the morning sky at the start of the month when it rises at 07:15 when it is mag +0.6 in Ophiuchus.
Venus is visible in the morning sky this month, moving from Scorpius to Sagittarius. It rises at
05:40 at the start of the month and at 06:50 by month’s end. It maintains its brightness at mag -3.9 during the month.

Mars is not visible this month.
Jupiter is at eastern quadrature on the 27th and is visible in the evening sky this month in Aries. It
rises during daylight hours during the month and sets at 01:15 by month’s end. It fades during the
month from mag -2.4 to mag -2.2.
Saturn is visible in the evening sky this month in Aquarius. It rises during daylight hours during
the month and sets at 19:10 by month’s end. It fades from mag +0.9 to mag +1.0 during the
month.

Uranus is visible in the evening sky this month in Aries. It rises during daylight hours during the
month and sets at 02:30 by month’s end. It maintains its brightness at mag +5.7 during the
month. It lies below Botein (Delta (δ) Arietis, mag +4.3).
Neptune is visible in the evening sky this month in Pisces. It rises during daylight hours during the
month and sets at 21:10 by month’s end. It maintains its brightness at mag +7.9 during the
month. It lies below Lambda (λ) Piscium, mag +4.5 which is in the Circlet asterism.

The Moon

The last quarter moon is on the 4th (03:30). The new moon is on the 11th (11:57). The first
quarter moon is on the 18th (03:53). The full moon is on the 25th (17:54).
Regular Stuff
5th am the 40% waning crescent lies below left of Spica (Alpha (α) Virginis, mag +1.0) at 03:00.
8th am the 13% waning crescent lies below right of Venus and above right of Antares (Alpha (α)
Scorpii, mag +0.9) at 07:00.

14th pm the 14% waxing crescent lies left of Saturn at 18:00.
15th pm the 24% waxing crescent lies below Neptune at 18:00.
18th pm the 57% waxing gibbous lies above right of Jupiter at 18:00.
19th pm the 67% waxing gibbous lies above Uranus at 18:00.
20th pm the 77% waxing gibbous lies below left of M45 – The Pleiades at 18:00.
21st pm the 85% waxing gibbous lies above left of Aldebaran (Alpha (α) Tauri, mag +0.9) at
18:00.
27th pm the 96% waning gibbous lies left of Regulus (Alpha (α) Leonis, mag +1.4) at 20:00.

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 09:00 on the morning of the 4th with a ZHR of 80. However the low
position of the radiant makes a much lower hourly rate 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 perfect year for this shower with a last quarter moon rising at 00:40 on the morning of the
4th, but it will not completely ruin the view and given the short days and long nights in January,
there is a good window to observe the shower pre moonrise.
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 (354) Eleonora is at opposition on the morning of the 20th and is mag +9.5 in Canis
Minor. It will be visible as soon as darkness falls on the 19th.
Finder charts and further information about other fainter asteroids can be found in the below
Information Sources and Links Section.

Comets

Comet 62P/Tsuchinshan is currently mag +8 and will fade during January. It moves from Leo to
Virgo and is visible from 22:00 during the month. It passes to the right of Denebola (Beta (β)
Leonis, mag +2.1) on the evenings of the 2nd and 3rd.
Comet 12P/Pons-Brooks is a very active comet and has gone into outburst on several occasions
in recent months, it is currently mag +10 and it is predicted to peak at mag +4 in April 2024. It is
circumpolar in January, so will be visible all night. It is in Cygnus during the month. It lies below
Sadr (Gamma (γ) Cygni, mag +2.2) on the evening of the 15th.
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.

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.

Clear Skies,

We at Big Bear Planetariums would like to thank Neill McKeown for sending us the Sky dairy each month.