What’s up?
May 2018
The month starts with a waning gibbous Moon, just past full, and reaches the last quarter on 8 May, with the new Moon following on the 15th. The first crescent becomes visible the next evening, the 16th, after sunset.
Most readers are probably aware that the Sun is rising later and setting earlier quite noticeably; those long languid evenings not returning till early next year! However, many people are not really aware that the Sun is also rising and setting much further north of east and west each day, or that midday shadows are now much longer than they were in December - every day the Sun crosses the meridian a little lower until the solstice next month. It is interesting to see how the sunlight reaches further into my living room every passing day.
The Milky Way is now also becoming more prominent and to me it is still one of the most spectacular sights in the night sky, but one needs to be at a really dark site to see the dust bands, nebulae and star clusters and to fully appreciate its beauty. Here binoculars are a great aid.
Looking west just after sunset, Orion is now well on its way out of the evening sky. It can be seen low above the western horizon. On the 17th, Venus can be seen close to a thin waxing (getting bigger) crescent Moon. It will be a pretty evening scene with Orion and the Great Southern Triangle-formed by Sirius, Procyon and Betelgeuse - perfectly placed to the upper left of Venus and the thin crescent Moon. To the right of these are the twins in Gemini, Castor and Pollux.
Scorpio is of course the only constellation that looks something like its name implies! It is now rising after sunset. Legend has it that the gods placed Orion and Scorpio at opposite ends of the night sky to prevent them fighting each other, and so as the one rises, the other sets.
To the upper left of Scorpio is the giant planet Jupiter.
At the heart of Scorpio is Antares, known as the rival of Mars; because they are similar in colour, but for different reasons. Mars reflects sunlight and appears red because of the soils on its surface. Antares is a red giant star, about 1 000-million kilometres in diameter, which is nearing the end of its life. Its surface has cooled to about 3 000 degrees, giving it its red appearance, but it is more than 9 000 times more luminous than our Sun and is 520 light years away. To the Chinese it was the “Heart of the Dragon”, the Romans called it “Cor Scorpionis” and the French call it “Le Coeur de Scorpion” - all of course mean “the heart of the scorpion”.
To the south, the Southern
Cross and the Pointers are now prominent. To the right, west of the cross, the second brightest star in the night sky, Canopus, shines brightly. Between Canopus and the Southern Cross, the False Cross can be seen: it is larger and not as spectacular as the real cross and does not have the distinctive pointers.
Finally, Canopus is of great significance to the Sotho people who call it “Naka”, the Horn Star, because when it is first sighted the Phalaphala horn is blown to mark the event. It also marks the new year and the beginning of winter for the Zulu people, who call this star iKwenKwezi.
The Garden Route Centre of the Astronomical Society of Southern Africa, Grassa, meets at 15:00 on the first Saturday of each month in the Catholic Church hall in Sysie Street, Sedgefield. Members of the public are welcome to attend. Contact Case Rijsdijk on 044 877 1180.