The night sky is a vast topic for which we could dedicate a whole issue, but with our focus on the remaining weeks of winter, we are going to offer some simple ways to explore some of the more common constellations, as we approach March and the Spring Equinox.
Since ancient times, the celestial sphere has been divided into various constellations, mostly dating back to antiquity, and usually associated with certain myths and legends. These days, the boundaries of the constellations have been fixed by international agreement, and their names are largely derived from Greek or Roman origin.
In this issue, we’ll be exploring in particular the northern and winter constellations, and what can be most easily spotted in the night sky during the month of March.
Observational Notes & Practical Tips Before we start its worth noting that stars that are visible change from month to month and conditions for observing them naturally vary over the course of the year. The stars described here can be observed by the naked eye or a simple pair of binoculars.
If you plan to head out please don't forget to wrap up warm! Star gazing means a lot of standing still so thick socks, thermals, a good waterproof coat and shoes, gloves and hat are all ‘musts’, plus a hot flask of something warm also doesn’t hurt having to hand!
Constellations & Asterisms There are a total of 88 constellations covering the entire celestial sphere, but 24 of these are located in the southern hemisphere and therefore not visable to those of us residing in the north. The names of the constellations themselves are expressed in Latin, depicting many familiar names from the 12 astrological star signs such as Leo and Taurus, to famous Greek mythological characters like Andromeda and Pegasus.
Aside from the constellations, smaller groups of stars that form part of the larger constellations are readily recognizable and also given individual names. These groups are known as ‘asterisms’, the most famous being the Plough, also known as the Big Dipper in North America. Below are a list of the some of the more interesting constellation names and their English translations, that read somewhat like a group of Harry Potter characters:
Aquila - Eagle Canis Major / Canis Minor - Big Dog / Little Dog Draco - Dragon Hydra - Water Snake Lupus - Wolf Monoceros - Unicorn Pyxis - Compass Ursa Major / Ursa Minor - Great Bear / Lesser Bear Vela - Sails Vulpecula - Fox
The Northern Circumpolar Constellations The northern circumpolar stars are the starting point for identifying constellations, and are visable throughout the year for those of us in the northern hemisphere. One in particular that is known to most is the Plough, which forms part of the large constellation of Ursa Major (The Great Bear).
The stars move due to the passage of the seasons resulting in Ursa Major lying at different points in the night sky during different periods of the year - spring south, summer east, autumn north and winter west. The seven stars of the Plough remain visable throughout the year anywhere north of latitude 40 degrees north.
As well as Ursa Major, the other notable constellations in the northern circumpolar include Polaris and Ursa Minor, Cassiopeia, Cephus, Camelopardalis and Draco.
All stars in the northern sky appear to rotate around Polaris, also known as the 'Pole Star', which sits next to the 5 main stars in the constellation of Ursa Minor.
On the opposite side to Ursa Major lies Cassiopeia, a highly distinctive cluster of five stars forming a letter ‘W’ or ‘M’ depending on its orientation. Provided the night sky is relatively clear, you will nearly always be able to see either Ursa Major or Cassiopeia, therefore being able to orientate yourself in the sky.
The Winter Constellations The winter sky is dominated by several bright stars and distinctive constellations. One of the most prominent is Orion, which includes the stars of Betelgeuse, Bellatrix, Mintaka and Rigel, forming the main body shape similar to an hour glass. The distinctive three star 'Belt' of Orion crosses its middle, and points downwards southeast towards the brightest star in the sky Sirius (Canis Major).
Also noteworthy is the almost perfect equilateral triangle, known as the 'Winter Triangle', formed by the large stars of Betelgeuse(Orionis), Sirius(Canis Major) and Procyon(Canis Minoris).
March at Night In March the Sun crosses the celestial equator on March 20th, at the vernal equinox, more commonly known as the Spring Equinox, which is when day and night are almost exactly equal length and the northern season of spring is considered to begin.
Looking North: Early in March one star stands out in particular due to its deep red colour. This is Cephei (The Garnet Star), due to its striking colour. It is a truly gigantic star, a red supergiant and one of the largest stars known. It is roughly 2400 times the diameter of the sun, and can be located at the southern end of the constellation of Cepheus, whose shape is rather like the gable end of a house.
Looking South: One of the other more prominent constellations in March is that of Leo (Leonis), with the backward question mark (or sickle) of bright stars forming the head of the mythological lion. Other notable constellations include Gemini and Cancer, which looks rather like a triskelion (the symbol for the Isle of Man) with its three legs radiating from a centre.
Moon Phases for March:
Day 1 of the New Moon - 13th March The days before, during and soon after the New Moon are best for star gazing because during this time the moon is barely visable in the sky, therefore not washing out the light from the stars.
Vernal Equinox - 20th March This is when day and night are of almost equal length and the northern season of Spring is due to begin. The hours of daylight and darkness change most rapidly around the equinoxes, with the other (Autumnal Equinox) falling in September.
Full Moon - 28th March When the moon is at its brightest and fullest. If it happens to be a clear night, this is a perfect time for an evening stroll lit by moonlight!
Some final notes...
Star Gazing Apps There are loads of really useful and well put together star gazing apps now available to download for use on your mobile phone, helping to make your star gazing experience easier and fun. I've included some recommendations here which are worth a look in:
- Sky View Lite - Star Walk 2 - Night Sky
Dark Sky Sites To get the best out of your star gazing experiences, why not visit a dark sky site once out of lockdown. There are currently thirteen dark sky sites based in the UK, three of which can be found right here within Wales:
Elan Valley Estate, Powys
Brecon Beacons National Park, Powys
Snowdonia National Park, Gwynedd
Dark sky sites have been recognized as areas free from light pollution, providing the perfect darkness for astronomical viewing. Further details regarding the sites above can be found on the International Dark Sky Association website at www.darksky.org