NIGHT SKIES OF JUNE

By Dr. N. T. Jiwaji

Tanzanians had the opportunity of viewing on June 15^th, the most amazing total lunar eclipse in recent times. The skies in June are free from clouds over Tanzania allowing millions of people to witness the event.

It was a truly total eclipse with the Moon totally blanketed by the Earth’s shadow with a darkness value of L = 1 by the Danjon scale. The eclipse was also the longest in ten years lasting just more than 100 minutes since the Moon crossed the Earth’s shadow along its diameter and hence through its center. Moon was well away from the edge of the shadow where very little earthlight can seep through. In most total lunar eclipses the Moon is near the edge of the shadow and takes on a bright orange colur due to earthlight from which the blue light has been scattered (bent out) by the Earth’s atmosphere.

The eclipse began with the eastern edge being blackened dramatically at 9:23 pm and the Earth’s shadow now orangey shadow crept slowly and symmetrically across the face of the extremely dazzling Full Moon. The Moon’s half degree face was fully covered in an hour and the total eclipse began at 10:22 pm. The eastern edge was now markedly dark orange and opposite end of the Moon bright yellow since it had just entered the Earth’s shadow. Fifty minutes later just after 11 pm the Moon became almost invisible with a dark brown colour and its features not visible even through binoculars. The reverse was now in progress as the Moon crept slowly to the opposite edge of the Earth’s shadow becoming brighter as it progressed and by 12:03 am, just past midnight, the eastern edge broke through and a sliver of the Moon’s disk began to be seen. The whole of the Moon was fully free of shadow by 1:02 am and the total lunar eclipse ended.

With the skies darkened remarkable it became a moonless night and all the sleeping stars hidden by moonlight could be seen during the one and a half hours of totality.

Saturn is the only planet that is visible in the early night skies and during the eclipse it shone sharply with unflickering brightness. Through a telescope its true beauty is recognized with the ring now distinguishably separate from the planet’s sphere. It remains close to Porrima a star in Virgo constellation. Over the coming days track the separation between the Saturn and Porrima to recognise the movement of the planet as it orbits the Sun.

One of the advantages of watching the skies from Tanzania, which lie on or close to the Equator, is that we are well positioned to see almost the entire sky from north to south. We can enjoy nearly quarter of all the constellations at any one time. The June sky is normally crisp and cool for a clear view of stars in spite or our city lights. The sky map shows us that now we can see, at a go, nearly 18 constellations and asterisms. Marked alphabetically from A to R these are, from south to north and east to west: A – Sagittarius the archer, B – Scorpius, the long winding shape of a scorpion with tentacles at the top and a sweeping tail ending in a double starred sting. C – is Ara the Alter while D – is Triangulum Australe, the southern triangle. E – is the famous kite shaped Southern Cross always pointing south. F – is the False Cross bigger than the Southern Cross and G – is Vela, the Sail. H – is the zodiacal constellation of Libra the scales of justice and I – is long Hydra the snake. J - is Virgo the virgin. K – is king Leo with an inverted question mark. L - is Cancer the crab. M – is Hercules. N – is Bootes the herdsman. O – is the Big Dipper seen as an inverted sauce pan with its edge stars always pointing north. P – is Ursa Major, the big bear. Q – is Draco the dragon while R – is the Little Dipper the little bear.

Among the bright stars are: ‘m’ – the closest star to us, Rigil Kentarus also known as Alpha Centauri; yet light traveling at 300,000 km per second still takes 4.3 years to reach us. Through a telescope you can distinguish it as a double star, though in fact it is a triple system with the third star not visible even through a telescope. ‘n’ – is Hadar also known as Beta Centauri. The pair rises up vertically in the evening skies in the southeast and rotates around the south pole, becoming horizontal as the night progresses. ‘o’ - is Antares the bright red star in the neck of Scorpius. ‘p’ – is Spica in Virgo while ‘r’ – is Regulus in the head of Leo. ‘s’ – is Procyon the small dog star. Just after sunset and setting in the southwest by 7:30 p.m. you can also see Sirius which is the brightest star in the sky and towards the south you will see the second brightest star in the sky, Canopus. The full glory of the dense concentration of stars and dust can be seen in the Milky Way which stretches across our sky at the moment from southwest to southeast. In very dark skies well away from city lights the Milky Way is awesome to see as a band of densely packed stars and nebule (interstellar clouds). In cities you can enjoy this concentration of stars and nebulae only if you have a pair of binoculars.

June 20^th is the day Solstice when the northern summers and southern winters begin.

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