Telescope House February 2024 Sky Guide
February, typically the shortest month with 28 days, extends to 29 this Leap Year, aligning our calendar with Earth’s rotation and orbit. The Gregorian Calendar, introduced in 1582, corrected issues in the previous orbitally inaccurate Julian Calendar. Leap Years maintain accuracy; for instance, 2024 is a Leap Year since it’s divisible by 4, not by 100 unless by 400.
The reason for this happening is simple - human imposed segmented time measurement doesn't match up completely with nature. As natural time progresses, our calendar, if left to its own devices, would begin to slip and misalign with the Earth's rotation and path around the Sun. Although this is only a very gradual process, it wouldn't be long before this got rather out of kilter. The process behind this thus; the exact time taken for our Earth to orbit the Sun once is just over 365 days. This period of time is known as - amongst other titles - an Astronomical Year and equates to around 365.242 days. Once these "extra" hours of an Astronomical Year are added up, they equate to a significant period of time, which if left unchecked would cause our Gregorian Calendar to start to slip in relation to Astronomical events such as the Solstices and Equinoxes of the year.
Pope Gregory XIII introduced the Gregorian Calendar in 1582, an improvement over Julius Caesar's Julian Calendar, known for its inaccuracies. Luigi Lilio, the Italian Natural Scientist behind its formulation, never witnessed its implementation. Leap Years, with a 29th February, were crucial for Gregorian accuracy, simpler than the Julian system. Despite its 1582 debut, Britain clung to the Julian Calendar until 1752.
Leap Seconds, like the last one added in December 2016, fine-tune timekeeping due to Earth's rotational changes influenced by factors such as atmospheric drag. Venus exemplifies the impact of atmospheric drag on rotation, with its day now surpassing its year. However, it seems as if the Leap Second’s days are numbered, as the international body that oversees weights and measures, the BIMP, voted in 2022 to stop adding leap seconds to Universal Time by 2035. Instead of adding leap seconds on regular intervals, time will be allowed to drift somewhat in relation to the Earth’s rotation, until it is corrected by the insertion of a leap minute every 50 to 100 years. How this will ultimately affect fine pointing of telescopes and other tracking equipment remains unclear at present. But as many of these use GPS, which has its own timestamp, separate from Universal Time, the offset of timing to the rotation of the Earth may be less pronounced.
The Solar System
Our natural satellite begins February in the expensive constellation of Virgo. At waning gibbous phase, the Moon will rise at a little before 12 am and transit at a little before 5 am on the morning of the 1st. It will set at a little after 10 in the morning.
Over the first week of February, the Moon will drift through Virgo into Libra and Scorpius, (shrinking in phase as it does) and on into the lowest parts of the ecliptic as seen from the northern hemisphere: Ophiuchus and Sagittarius. After this, it will start to rise from its most southerly point, passing Venus and Mars (in eastern Sagittarius) and Mercury in Capricornus, where it joins the Sun on the 9th of February, where it will become New.
Once past new phase, the Moon becomes an evening object. The first few days after Mew will find the Moon a difficult object to locate in the sky. It will pass Saturn in Aquarius on the evenings of the 10th and 11th and will start to become visible more easily after the 12th when it enters Pisces and gains a little in altitude and in phase.
Although the northern hemisphere is not experiencing Spring as yet, February’s waxing crescent phase represents the first of what is commonly known as the Moon’s “High Spring Crescent” phase. This occurs for observers in the northern hemisphere during springtime in the evenings. It is caused by the steeply setting Ecliptic plane as seen from temperate northern climes at this time of the year. The Highspring Crescent phase offers observers some of the best opportunities to view the moon in the evening time and if the weather is kind should not be missed.
The moon will continue to rise up through Pisces, skirting over into the borders of Cetus, the whale on the evening of the 13th of February and then rejoining Pisces on the 14th. The Moon will enter Aries on the 14th of February and pass close to Jupiter on the evening of the 15th. The following evening, the Moon will attain first quarter phase. By this point it will rise at just before 10 am, transiting at a little past 6 pm and setting at a little before 1:30 am the following morning (all times GMT). From just before 8 pm on the 16th, the Moon will be found technically within the boundaries of the Pleiades. While it won’t be an occulting any major members of arguably, the most famous star cluster, the two objects will be a very pretty pairing in the early-to-mid evening sky.
The moon reaches its most northerly point of the ecliptic on February 19th and will then travel through Gemini and Cancer and on into Leo where it will become Full on February 24th. By this point, the Moon will rise at a little before 6:45 pm (GMT) and transit at a little after midnight, setting at just after 7:30 am the following morning.
The final few days of the month will see the Moon exiting Leo and entering back into Virgo, where we first found it. By the end of February on the 29th – a leap day – it will sit on the borders between Virgo and Libra. Our natural, satellite will be at waning gibbous phase, illuminated by around 80% and rising at just after 11:30 pm (GMT) on the 29th.
Although the Sun is low in the sky for northern hemisphere observation, it is becoming more and more active within its 11 year cycle, as Tony Broadhurst's Hydrogen alpha picture below, taken through a Lunt LS60 in early January last year, clearly depicts. Further and more detailed observations of the Sun can be found by referring to Michel Deconinck’s monthly newsletter here: https://astro.aquarellia.com/doc/Aquarellia-Observatory-forecasts.pdf - this newsletter also covers occultations and other observations from Europe and is well worth checking out.
Although the Sun is not especially favourably-placed for northern hemisphere observers at this time of year, the very limited wavelengths of Hydrogen Alpha observation can (to a certain extent) ride out poor seeing conditions, caused by low elevation. Even when the Sun is very low in the sky, it is still possible to see and image significant detail on the solar disk and in the atmosphere surrounding it, as Tony's image shows. Latest predictions put the current cycle reaching its peak in July 2025, so we are just under 18 months off peak solar activity in this current cycle. There's certainly plenty to see on, or around the Sun at present - it'll be interesting to see how much more there is to come.
The solar system's smallest true planet starts February as a resident of Sagittarius. Found alongside the diminutive Mars and the much brighter Venus in the morning sky, Mercury displays a -0.3 magnitude, 5.2 arc second diameter disc on the morning of January 1st. From a latitude of 51°, Mercury stands just over 4° high above the horizon as the sunrises, making it extremely difficult to see from higher northern latitudes. As the planet is heading sunward, the situation does not improve as the month continues.
Mercury is in descending node, heading below the ecliptic plane and traveling to the south of the Sun. The rest of the month sees Mercury getting closer and closer to our parent star, making it an impossible to observe from the temperate northern hemisphere. Mercury reaches superior conjunction on February 28th when it will be found just under 2° to the south of the Sun in Aquarius. We won’t see much of Mercury until it has gained significant separation from the Sun on the eastern “evening” side of our parent star, which will not occur until later in March. The good news for observers in the northern hemisphere is that Mercury’s March apparition will be one of the best times to observe the planet during 2024. February is extremely poor in comparison!
As previously mentioned, Venus is also a resident of Sagittarius during the first part of February. The morning of the 1st finds Venus standing at around 10° above the horizon (as observed from 51° north) and shining at a brilliant -4.0 magnitude. The planet shows a 12.2 arc seconds diameter disc which is illuminated by around 86%.
While we have been extremely fortunate to observe Venus in the mornings in a very favourable location in the sky for the past few months, as mentioned, in last month's sky guide, this period is drawing to a close. While the planet is still separated from the Sun by just over 30° at the beginning of February, from higher northern latitudes, it appears to be sinking lower and lower in the sky with every coming morning. By the time we get to mid February, Venus will stand just over 7 1/2° above the horizon as the Sun rises. The planet will have faded fractionally to -3.9 magnitude and now displays an 11.6 arc seconds diameter disk. The reason for this night decline is that Venus is drawing away from us on its faster interior orbit around the Sun though will not come to superior conjunction as seen from earth until early June.
By the time we get to the end of February Venus will be standing Just over 5 1/2° above the horizon at daybreak. It will remain static and brightness at -3.9 magnitude they will now show an 11 second diameter disc. The morning of the 22nd finds Venus and the much fainter Mars separated by just over half a degree in the sky. While it be perfectly possible to see Venus with the naked eye, Mars will be much trickier and will probably require binoculars to see at this point.
At +1.3 magnitude, showing a four arc second diameter disc, the planet Mars presents less than ideal observational circumstances at the beginning of February. As previously mentioned, like Mercury and Venus, it is a resident of Sagittarius during the early part of the month - though will be very tricky to pick out in the early morning glare, before sunrise. The morning of the 1st sees Mars attain the height of a little over 5 1/2° (from 51° north) as the Sun comes up. Most people will require extremely clear skies and binoculars to be able to see where Mars is at all. Whereas Mercury and Venus are both headed towards the Sun at the beginning of February, Mars has emerged from superior conjunction at the end of 2023 and is steadily drawing away from our parent star, as seen from our perspective here on Earth. By the time we get to mid-month, Mars will be 24 1/2° to the west of the Sun in the morning sky and while it won’t be much higher than it appeared at the month's beginning, will be coming into close proximity with the much brighter Venus. The morning of the 22nd is when the two planets are to be found closest together and separated by just over half a degree. As we mentioned previously, while you won’t need binoculars to be able to make out Venus, you most certainly will do to be able to see Mars at all – though clouds, atmospheric conditions and catching both planets as early as possible after rising will all play a part in the potential success of observing this conjunction.
The King of the Planets continues to be extremely well-placed for evening observation during the entirety of February. A resident of Aries, Jupiter will be at -2.4 magnitude and displaying a 39.6 arc second diameter disk at the beginning of the month. It will rise at a little after 10:30 am, transiting at a little before 6 pm and setting at 1 am the following morning.
By the time we get to mid-month, not a huge amount has changed. Jupiter has faded fractionally to -2.3 magnitude and now displays 37.9 arc second diameter disk. At this time of the month, the planet will have transited in the south by the time the Sun goes down and will be standing at around 52 1/2°, above the horizon at Sunset (as observed from 51° north). The 14th and 15th see the Crescent Moon line up alongside Jupiter in Aries - the two forming a very striking pair in the early evening sky.
By the time we get to the end of February, Jupiter will have faded a little further to -2.2 magnitude, now displaying a 36.5 arc second diameter disk. The planet will rise at a little before 9 in the morning, transiting at a little after 4 pm and setting at around 11.30 pm.
As usual, there are some interesting mutual transit events to observe on Jupiter. The evening of the 1st sees a mutual Great Red Spot and Io/Io shadow transit taking place, which peaks at around 5 pm (GMT). Although technically taking place in daylight, there is a mutual GRS and Ganymede transit, which peaks at around 3:30 pm on Feb 4th. There is another GRS and Io transit, which peaks at around 6 pm on the 8th February. The 11th February sees a mutual GRS and Ganymede transit, which peaks at around 5 pm. There’s another Io and GRS transit, which peaks at around 7 pm on February 15th. February 22nd sees a mutual GRS IO and Callisto transit, which peaks at around 8:30 pm. February 25th, sees an impressive mutual GRS and Europa transit with moon hanging over the Great Red Spot itself - this peaks at around 5:30 pm.
As mentioned in last month’s, sky guide, the window for meaningful observations of Saturn in the evening sky is closing - and indeed, comes to a complete end by the latter part of the month. The 1st finds the planet at a visual magnitude of +1.0, displaying a 15.7 arc second diameter disk. The planet will transit in the south at around 2 pm (GMT) and will set at a little after 7 pm. While it is perfectly possible to observe Saturn once the Sun has set (it stands around 17 1/2° high – as observed from 51° north – in the south-west, in Aquarius), there is only a two hour window for observation in a darkening sky at the beginning of the month. With the Sun setting later and later, as time progresses and Saturn drawing closer to the Sun as the month goes on, evening observations become steadily more difficult.
Mid-February will see Saturn standing around 8° high (from 51° north) in the west as the Sun sets. It will remain at +1.0 magnitude and will start to be difficult to see in the glare of the evening sky. At this point, Saturn will set around hour after the Sun, making it a tricky target at best.
Saturn reaches superior conjunction, the opposing side of the Sun, as observed from Earth, on February 28th and will remain invisible for a period of time until it re-emerges on the morning western side of the Sun.
Uranus and Neptune
The outer gas giants are both observable during February, though it is Neptune, which is closer to Saturn in the sky, that presents the larger challenge of the two. Neptune will stand around 31 1/2° high as the sunset on first (as observed from 51° north). At +7.9 magnitude and displaying a tiny 2.2 arc second diameter disk, the solar system’s outermost true planet will stand 18 1/2° above the horizon by the time true astronomical darkness has fallen in mid northern latitudes. As the month progresses, the window of observation of Neptune closes to by the time we get to the end of the month, Neptune will sit just 16° from the Sun and will start to become to all intents and purposes, unobservable. Though it will be another 17 days before it reaches superior conjunction in mid-March.
By way of contrast, Uranus is much better situated for evening observation, lying a little to the east of Jupiter in Aries. It is a steady +5.7 magnitude, displaying 3.6 arc second diameter disc at the beginning of the month.
We often remark that Uranus is potentially visible with the naked eye – though only buy those with very keen eyesight, from extremely favourable locations. However, the brilliant Jupiter lying just under 12° to the west of Uranus in the shared constellation of Aries, makes for a useful waypoint to find the mysterious outer world. Those with reasonable size telescopes, using high magnification can in certain circumstances, see albedo features on Uranus. This is a test of observing patience and skill – and also the optics of the Telescope observers are using. Even those with smaller instruments will still see Uranus as a green–grey disc.
Periodic comet P/62 Tsuchinshan has been the brightest cometary prospect during the early part of 2024. Peaking at around 8/9th magnitude, it is now fading and won’t be particularly prominent, but it will be well- placed for morning observations in Virgo. Once the Moon is out of the way in the early part of the month, the comet should be relatively straightforward to find, tracking slowly through the skies north of the “bowl“ of Virgo.
Comet 12/P Pons-Brooks has undergone a couple of significant outburst events, increasing brightness beyond predicted levels, While the comet is in a reasonably favourable part of the sky for observation, despite these outbursts, it is still relatively faint at around 8th magnitude at time of writing. Tracking through Cygnus, Lacerta and Andromeda during February, it will still be reasonably high in the sky when astronomical dusk occurs at the beginning of the month.
The comet is still brightening and while definitely the preserve of binoculars and telescopes during February, could reach technical naked eye brightness as it reaches perihelion in April - though naturally, it will be much closer to the Sun when this occurs and more challenging to observe.
There are no bright or notable meteor showers during February. However, whenever you are out under a clear, reasonably dark sky, there is still the opportunity to see sporadic meteors. These are not necessarily associated with any particular meteor shower and can come from any direction in the sky.