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March is a longer month, following the relatively short month of February and it brings forth the highly anticipated regular annual astronomical event, the Vernal Equinox. This year, the Vernal Equinox will take place on Monday, 20th March, marking the occasion when the Sun moves from the southern celestial hemisphere to the northern celestial hemisphere, resulting in equal periods of day and night in certain parts of the world. While this equality of day and night is a generalisation and is not be precisely accurate for those in extreme northern or southern regions, those of us in the northern hemisphere will all start to enjoy longer days, officially welcoming the arrival of Spring. Conversely, for those residing in the southern hemisphere, the Vernal Equinox coincides with the Southern Hemisphere Autumnal Equinox, with darkness slowly but surely creeping in.
Moreover, the Vernal Equinox triggers a time shift, where the majority of the northern hemisphere adjusts their clocks forward by one hour to Summer Time. While Europe observes this shift on Sunday, 26th March, other countries like the United States may adjust their clocks earlier in the month. Around the Vernal Equinox, the southern hemisphere experiences a return to standard time, where their clocks are set back by an hour. It's important to note that equatorial regions experience more consistent hours of light and darkness throughout the year and hence do not require similar time adjustments.
Wherever you are in the world there’s plenty to see in the skies above us this month, so let’s find out what’s in store for us.
The Solar System
The Moon
Our natural satellite begins March in Taurus, at a 9 day old waxing gibbous phase. Rising at a little after 11am the previous day, the Moon will set at a little before 4.30am (GMT).
During the first week of March, the Moon will coast over the most northerly part of the ecliptic, passing through Gemini and Cancer and down into Leo, where it will become Full on the 7th. As is customary, we remind readers that this part of the month won’t be the most opportune for deep sky observations, or imaging (except for those using very narrowband filters).
Beyond Full, the Moon starts to wane as it passes from Leo, on through the expanse of Virgo and into the more southerly reaches of Libra, Scorpius and the non-zodiacal constellation of Ophiuchus, where it will reach Last Quarter phase on the 15th. By this point in the month, the Moon will rise a little after 3am, leaving a sizeable part of the night free from lunar interference.
Beyond mid-month, the Moon will drift through the “bottom” of the ecliptic (from a northern hemisphere perspective), in Sagittarius, before starting its climb up through Capricornus and on into Aquarius, where it will meet the Sun and become New on the 21st, just a day after the aforementioned Vernal Equinox.
Emerging from the Sun’s glare as an evening object, the Moon then begins one of its best crescent displays of the year. This part of the cycle is what we have referred to as the High Spring Crescent phases, as seen from the northern hemisphere. This is caused by the high angle of the ecliptic plane, as it appears from temperate and higher northern parts of the Earth at this time of year. This gives observers in these locations some of the best opportunities to observe the evening Crescent Moon at significantly higher separation from the horizon than at other times.
During the next week, the Moon will rise past Jupiter, in Pisces, on the 22nd (though will be at a tiny 1.3% illumination and we’ll be easily missed). The 24th sees the Moon sitting a little to the north of Venus (by just under 3 1/2 degrees), at 11% illumination, as the Sun sets - the two forming a very pretty pairing in the evening sky. The following couple of evenings finds the Moon in Taurus, near both the Pleiades and Hyades star clusters.
Mars is joined by the Moon on the 28th, while still in Taurus, the two bodies separated from each other by just over 3 degrees. The following evening finds the Moon back at First Quarter phase, while in Gemini. The Moon then becomes gibbous again as it continues its path through Gemini and on into Cancer, where it ends the month on the 31st, at around 68% illumination, rising at a little after 1pm (BST).
Mercury
Mercury spends much of the beginning stages of March in a very poor position for observers in much of the northern hemisphere. As covered in previous sky guides, just as the evening ecliptic “sets” at a very high angle for northern hemisphere residents, the morning ecliptic “rises” very shallowly, at this time of year. This, coupled with Mercury’s march in a descending sunward direction, means it will be extremely low to the horizon, as the Sun rises and unobservable for many of us.
Mercury reaches superior conjunction - the opposite side of the Sun as visible from the Earth - on March 17th. After this it will emerge from the glare of our parent star as an evening target. This will have great results from a northern hemisphere perspective, as Mercury will rapidly climb into the sky, away from the Sun.
By the time we reach the end of the month, Mercury will be in the same area of sky as Jupiter - the two drawing together in close conjunction on the evening of the 27th, separated by just under 1 1/2 degrees. By this point, Mercury will be -1.5 magnitude. This is fainter than Jupiter, but nonetheless a very reasonable brightness and this and Jupiter’s proximity around this time should make it easier to find.
Mercury ends March at a respectable -1.1 mag., at 80% illuminated phase, showing a diameter of 5.8 arc seconds. Standing at just over 12 degrees high at sunset (from 51 degrees N), the innermost planet finishes the month on a real high - certainly in comparison with the month‘s beginning.
Venus
We begin March in spectacular fashion with Venus in very close conjunction with Jupiter. The evening of the 1st sees the two planets separated by just 39 arc minutes - 2/3rds of a degree - this will mean that they are observable in the same field of view of a telescope, using modest magnification. This should be quite a sight even with the naked eye. The two planets will stand around 18 degrees high as the Sun sets (from 51 degrees N), making this event easy to observe for those with a clear westerly horizon. At -4.0 mag and -2.1 respectively, Venus and Jupiter are the 3rd and 4th brightest natural objects in the sky, so this conjunction is likely to capture the attention of those less interested in astronomy.
Whereas Jupiter is sinking towards the Sun, Venus is drawing away from it, so the two planets draw away from each other fairly quickly, once the beginning of the month is over. By mid-month, the two will be separated by 13 degrees. The 15th March finds Venus no brighter in magnitude from the month’s beginning, but it will have increased its separation from the horizon to 28 degrees at sunset (from 51 degrees N).
By the end of the month, Venus’ brightness stay static at -4.0 mag. However its phase will have decreased to 77%. In most situations, decreasing phase goes hand in hand with modest loss of brightness. However, in Venus’ case at present, while its phase decreases, it is drawing closer to us, expanding its size. It’s this expansion that allows Venus to remain static in brightness, as its phase decreases - essentially the illuminated area of the planet stays the same.
We leave Venus on the evening of the 31st, standing just under 32 degrees in elevation (from 51 degrees N) as the Sun goes down.
Mars
Mars is very well situated for evening observation, as a resident of Taurus. However as mentioned in previous month’s sky guides, the window for really rewarding observations of Mars is definitely closing and the quality of views in telescopes will degrade significantly from the month’s beginning to its end.
March starts with Mars sitting in between the “horns” of Taurus. At +0.4 mag and 8.1 arc seconds across, it will need reasonable magnification in a telescope to reveal the mottling of the major continental-sized features on its surface.
Mid-month will find Mars having drifted further westward in the ecliptic, but still very much within the borders of Taurus. By this point in time it will have shrunk to 7.2 arc seconds diameter and displays a brightness of +0.7 mag.
By the time we get to the end of March, Mars will now be a rather small 6.5 arc seconds diameter target at +1.0 magnitude. The latter part of the month will see the planet having crossed the border from Taurus into Gemini. While we would never want to dissuade anyone from turning a telescope on any planet object of interest in the night sky, the end of March will see Mars having lost nearly 2/3rds of its surface area, when compared to its peak around December 2022’s opposition and being nearly three magnitudes fainter than it was then. Mars’ comparatively small diameter, coupled with ever increasing distance from Earth, means one thing: the trend is downwards as far as observations of the Red Planet go. The simple fact that the outer planets appear earlier and earlier in the evening sky, post-opposition, means less experienced observers often start to notice Mars, once it’s a long way past its peak. We have to wait until January 2025 until Mars is back to opposition - so it’s some time until the planet is back to its best.
Jupiter
Jupiter, being by far the largest planet in the solar system, never suffers from the same drop off in brightness that the diminutive Mars does. No matter what part of its orbit it is on, the King of the Planets always presents a decent sized and suitably bright target in a telescope. As discussed above, the highlight of March as far as Jupiter is concerned is it’s very close conjunction with Venus on the 1st. At -2.1 mag and 34.2 arc seconds diameter, Jupiter will present an impressive sight in practically any telescope.
However, as it sits around 25 degrees high in the sky at sunset (from 51 degrees N), Jupiter will be below the “magic” 30 degrees of elevation, for many northern hemisphere observers and this will start to tend to lessen the quality of atmospheric seeing conditions, when looking at the planet with significant magnification. As mentioned, Jupiter is heading sunwards, and this means as the month progresses, it will appear to sink further down in the sky, settling earlier and earlier as it does. This will naturally have a negative affect on observations, as the window of time in which we can perform these closes.
Mid-month will see Jupiter standing just under 17 degrees high at sunset (again, as observed from 51 degrees N), itself setting just under two hours after the Sun.
By the time we get to the end of March, Jupiter will stand just 6 degrees above the horizon, setting just over 40 minutes after the Sun does. By this point in time, Jupiter is under two weeks away from superior conjunction and the evening window for Jovian observations will effectively be shut.
Saturn
Saturn is emerging slowly from last month’s superior conjunction and is in a very poor position for temperate northern hemisphere observations at the beginning of March. Sitting alongside the equally difficult to observe Mercury on the 1st.
By the end of March, Saturn sits around 37 degrees to the west of the Sun, at +1.0 magnitude brightness, displaying a 15.7 arc second diameter disk. It will stand just under 8 degrees high at sunrise (from 51 degrees N), but will still be low and prone to poor seeming conditions. Subsequently, moderation is recommended for those up early enough to observe it, in both magnification used to observe the planet and expectations of how it will appear in a telescope.
Uranus and Neptune
Uranus is well situated, in Aries, at the beginning of March. At +5.7 magnitude, it can be glimpsed by those with reasonable eyesight from a very dark location, but is much easier in binoculars. At 3.5 arc seconds across, it is similar size to many planetary nebulae - and although a bit brighter, can appear quite similar in telescopes. Uranus will still be of significant altitude - just under 38 degrees (from 51 degrees N) - as true astronomical darkness kicks in at this latitude, making identification of this distant world somewhat easier.
Uranus’ neighbour, Neptune, is much closer to the Sun in Aquarius and comes to superior conjunction during mid-March (15th), making it unobservable - until it gains suitable distance from the Sun in the morning sky.
Comets
Comet C/2022 E3 (ZTF) has faded rapidly from its peak, which it reached in late January/early February. Found in southern Taurus on the 1st, it is predicted to be around the 8th magnitude and subsequently only observable in telescopes and powerful binoculars, from suitably dark locations. The area that ZTF occupies at the beginning of the month is easily found: trace a line down south from Aldebaran (Alpha Tauri) and a line west from Mintaka (Delta Orionis), the highest and furthest star to the right of the three in the belt of Orion (as viewed from the northern hemisphere). Where these two lines meet is the area of sky the comet occupies. The comet is travelling southward and crosses over the border into the large, but somewhat sparse constellation of Eridanus, the River on the 3rd March. It continues its course south and slightly to the east during the rest of the month, until it ends March about 5 1/2 degrees to the west of Rigel (Beta Orionis). By this juncture, ZTF will have faded dramatically and is predicted to be around the 11th magnitude.
It’s worth mentioning that the previously covered comet C/2017 K2 PanSTARRS will be putting on a very respectable performance for those in the southern hemisphere. It is found near Archenar (Alpha Eridani) at the beginning of the month. Some current brightness predictions put it at around 6th magnitude, some up to a couple of magnitude fainter. The most recent observations, at time of writing, peg it at around 8th magnitude at best, which is still somewhat higher than initially predicted. Sadly, this comet is only observed in the southern hemisphere at present.
Meteors
There are no major meteor events predicted for March. However, sporadic meteors can be seen at any time during the night.
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