Orion’s return to our night sky heralds start of summer
THE MONTH starts with a thin waning crescent Moon that becomes new on the 3rd, with the first crescent becoming visible the following evening after sunset.
The summer solstice is on the 21st and is the day that we have the longest “day” and so also the shortest night. It is, however, not the time of earliest sunrise and latest sunset. Earliest sunrise was on the 6th and latest sunset will be on January 7th. The reason for this is that Earth does not travel at a constant speed around the Sun since its orbit is an ellipse.
This month there will no doubt be quite some publicity about Comet Ison. Unfortunately it will not really be visible from the southern hemisphere. It passed close to the Sun (perihelion) on Thursday, when it was only 1.86 million kilometres above the Sun’s surface. After rounding the Sun, it becomes visible again ( northern hemisphere) early next month and it might be very bright, or it might not. For those interested there will be information on the Astronomical Society of Southern Africa website: http://assa.saao.ac.za.
The arrival of summer is heralded by the return of the constellation of Orion, the Hunter, to the evening sky, ans also marks the beginning of a more interesting night sky. By mid-month, Orion will be visible low in the north east after sunset. For the Tswana, the stars of Orion’s sword were “dintsa le Dikolobe”, three dogs chasing the three pigs of Orion’s belt. Warthogs have their young while Orion is prominent in the sky at this time of the year, and usually have litters of three. This I think makes this name far more appropriate for us in South Africa.
To the west, or left, of Orion is the small cluster of the Hyades in the constellation of Taurus the Bull with the bright orange-red star Aldebaran in the foreground. Only 60 light years away it is the eye of the Bull. Still further west is the small and bright cluster of isiLimela, also known as the Pleiades or the Seven Sisters, and beyond that is the Great Square of Pegasus. A line from the three bright “belt stars” in Orion, through Aldebaran and isiLimela will end up at the Andromeda galaxy to the lower right of the Great Square.
Venus is still visible after sunset, shining unmistakably brightly low in the western sky, and between the 14th and 17th a waxing gibbous Moon will be passing by the Hyades in the north. To the south, the Southern Cross and the two Pointers, alpha and beta Centauri, are visible low above the horizon. Our two nearest neighbouring galaxies, the Large and Small Magellanic Clouds are clearly visible well above the Cross, but you will need dark skies to spot these two fuzzy patches.
Archenar is nearly overhead while Canopus, the second brightest star in the sky, is visible in the south-east, and is also known as Naka or Nanga, the Horn star. Among the Venda, the first person to see Nanga ( Canopus) in the morning sky announced his discovery by climbing a hill and blowing a sable antelope horn (Phalaphala).
There is the usual open night at the Observatory on December 14 at 8pm. Visitors will have a chance to look at the night sky and attend a lecture by Dr Christian Hettlage on “The star of Bethlehem”.
The Sky Guide Africa South is now available from most good booksellers and is the ideal Christmas present for readers with an interest in the night skies of southern Africa. I find it indispensable and a copy travels with me wherever I go.