The Night Sky as a Seasonal Marker

From a Southern Hemisphere Perspective

Due to the Earth’s orbit around the Sun, the constellations seen in the night sky change throughout the year. In the southern hemisphere the constellation of Orion, the great hunter from Greek mythology, can be seen during summer evenings. Reversed to the northern hemisphere, Orion appears upside down in our Australian skies. Look early in the night sky low in the north east from November, sitting overhead throughout February, and sinking low in the north western sky come April. 

Between Orion’s legs and hanging from his belt is Orion’s sword, or the handle of Australia’s famous saucepan. This also appears as a line of three stars, with the middle one not actually a star, but a hazy cloud known as the Orion Nebula. A nebula is a giant cloud of dust and gas in space. Some nebulae, including this one, are stellar nurseries where new stars are being born. Observations of the Orion Nebula or M42 have revealed approximately 700 stars in various stages of formation within it. Being the nearest large star-forming region to Earth, this nebula can easily be seen and with binoculars, appears as a luminescent fog. Nebula comes from Latin and translates as ‘mist’ or ‘cloud’.

Following the line from Orion’s Belt westward will bring you to the open star cluster Pleiades, also known as the Seven Sisters. It can best be found with your peripheral vision, appearing as a small cluster of faint light. The heliacal rising (a star's first emergence and annual rise immediately before dawn) of the Pleiades heralded the start of the ancient Mediterranean seafaring season in the northern hemisphere, signalling the time of fairer weather. Its dawn setting marked the season’s end. In Australia the Pleiades appear before dawn around the winter solstice. They are a significant indicator of weather change for Indigenous cultures, signalling the onset of colder nights.

Following the line of Orion’s belt in the other direction leads to Sirius, the brightest star in the night sky and found in the constellation Canis Major. Canis Major is known as the Big Dog and the hunting companion of Orion. Like Orion, Sirius is easily seen throughout summer, and is high in the southern sky at midnight on New Year’s Eve. Further up from Sirius at this time of year you can also see Canopus, the second brightest star in the night sky.

The Celestial Emu, or Emu in the Sky, is the shape outlined by the dark and light areas of the Milky Way. The Emu is not the stars themselves as Aboriginal astronomy also observes the ‘negative’ or dark spaces in the night sky. Many different language groups across Australia have different names and stories associated with the Emu in the Sky. In Australia, the Emu can be well seen in more rural night skies. During autumn the glow of billions of stars extends from the west across the sky to low in the southeast. In winter it is low in the southwest extending to the northeast.

The constellation of Scorpius is in the sky during winter evenings. At this time of year, Scorpius lies high in the eastern sky near the centre of the Milky Way. Antares is the red heart of the scorpion and is a good way to navigate your search. From here find the three bright stars above that form a T shape that is the scorpion’s forehead, and then the large hook of stars that are the tail below. There is a myth that says Orion keeps far away from Scorpius because he was killed by the poisonous sting in the scorpion’s tail.

The Southern Cross is a collection of stars within the Crux constellation. As the Earth rotates, it appears to move in the sky around the South Celestial Pole. During the night it may appear the right way up, lying on its side or upside down depending on the time of night and time of year. 

As a calendrical marker, The Southern Cross can be easily seen in the evenings from March to August in Australia, being low in the sky for the remaining months. In April it is on its left-hand side in the early evening and becomes more upright towards midnight. Early in the evening in June the Southern Cross can be found high in the sky in an upright orientation that is seen on the Australian flag. A few months later it will be lying on its right-hand side early evening in the south-west and late in the year it will be upside-down and low in the sky.

Centaurus, the Centaur, surrounds the Southern Cross on three sides with the Pointer Stars forming the front legs of the Centaur. The brightest of the two, Alpha Centauri (furthest from the Cross) is the closest star to our Solar System, a little over 4 light years away.  Those that know the 1960s series ‘Lost in Space’ or its 2018 revival, will know the Robinson’s primary mission was to get to alpha Centauri, humanity’s only hope of escaping threats and continuing civilisation. It was expected to take a five-and-a-half year journey but with our current technology, the estimate is more like 6,300 years. 

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