Finding the Southern Cross (visible from January to October)
The WCE students were introduced to the incredible world of stargazing as part of the survival aspect of the programme. Emphasis was placed on the Southern Cross in order for them to be able to determine where south is. Knowing how to determine where north, south, east and west lies is an important part of survival. Below is a little more information on how to determine SOUTH…so be sure to glance up at the magnificent stars when next in the bush.
Next to the Southern Cross is a pair of pointers, namely alpha centauri and beta centauri. Alpha centauri is the brightest and furthest pointer from the cross, and forms a distinct “asterism” which is a compact pattern of stars that is smaller than a constellation. Alpha centauri consists of two stars that are only visible with a telescope. These two stars (alpha centauri A and alpha centauri B) take about 80 years to orbit around each other. Beta centauri appears as bright as alpha, but is far more distant and luminous … It is 14000 times brighter than the sun! When the cross is upright, the pointers will be on the left hand side. Together, they are some of the brightest stars in the sky.
The cross may not always be upright with the pointers to the left. When it is high in the sky, the pointers are to the left. Half way up it lies on its side with the pointers above or below. Almost at ground level, the cross will be upside down with the pointers to the right.
The Crux Stars
The 4 stars of the Southern Cross are further away than alpha, but not as close as beta. Alpha, beta and delta crucis are approximately 350 light years away. Gamma crucis is 88 light years from earth.
Alpha crucis is a triple star system with 2 bright suns close to each other and a fainter sun on the outside.
The Basotho bushmen see the Southern Cross as a giraffe with an outstretched neck, some see a lion, whilst the Zulus see it as the tree of life.
Finding south using the Southern Cross
Extend the axis of the cross like the tail of a kite, then intersect with a line bisecting the pointers. The point where the lines intersect is very close to the south celestial pole where the earth’s axis points into the southern sky. This pole is visible anywhere in the southern hemisphere and lies directly south.
A tall Camel Thorn Tree stands proudly under the star-filled night sky. With the Milk Way burning brightly, a hidden moon brightens the Kalahari sky.
The Milky Way
The Milky Way is the visible portion of our galaxy that forms an encircling luminous band. On winter evenings the Milky Way stretches high above and we can look directly towards the centre of the galaxy. On summer evenings we gaze in the opposite direction, away from the centre towards the edge of the galaxy. We still see the Milky Way, but less impressive as we are looking towards the outer region of our city of stars. In general the glow of the Milky Way comes from stars several thousand light years away. These account for almost everything we see in the sky. A few objects we see are not so far away as long as they are not seen too close to the sun.
Those east of the sun are visible in the night sky, while those west of the sun are visible in the morning sky. Nearby planets are too distant to be seen as discs, and instead look like very bright stars. One of these is Venus, which is sometimes bright enough to be visible in daylight.
A traditional belief around the Milky Way is that it was created when a girl threw wood ashes from a campfire into the sky to help a lost hunter find his way back to camp. She later created some brighter stars by throwing roots into the sky. According to legend, the white stars are ready to eat, whereas the red stars are old roots that are no longer edible.