Planet string in JUNE NIGHT SKIES over Tanzania

JUNE HIGHLIGHTS

· String of planets lined on the ecliptic

· Venus-Jupiter closest together 30 June

· Moon close to Venus-Jupiter 19, 20, 21 June

· Mercury 22deg, close to Aldebaran 24 June dawn skies

· Moon close to Saturn 28 and 29 June

· Ramadhan First Crescent 17 or 18 June

· Northernmost position of Sun 21 June

· Southern Cross pointing south

· Big Dipper points north

ISS - International Space Station visible 29, 30 June

The weather is very unpredictable with the sky sometimes clouded and even rain in May!! However, there are sufficiently frequent clear, cool, steady night skies that will allow you to enjoy the planet show unraveling this month.

Venus and Jupiter are extremely bright and easy to pick out near the west horizon at an elevation of about 30 to 40 degrees, from sunset until 8 or 9 pm, with the more brilliant Venus slowly shifting away from the Pollux-Castor pair of Gemini (the Twins) constellation. At the same time Venus is inching close to Jupiter and meet on 30 June.

Venus is now at its maximum elevation of 43 degrees and, when viewed through a telescope, it changes its shape from half to crescent while growing larger day by day as its orbit brings it closer to Earth. After lighting our evening sky since the beginning of the year, it will rapidly descend over the next two months and disappear from the evening sky by the end of July only to reappear as a morning star by the end of August.

Jupiter will also descend over the next two months and disappear below the west horizon by the mid-August and will reappear again after six months in the night skies rising in the east from February next year.

Venus remains close to the Sun and appears as evening and morning star because its orbit is inside that of Earth, which is also the reason why its shape changes from full to half to crescent when we observe it from Earth. Jupiter is very distant planet orbiting outside the Earth’s orbit hence it can shift in the sky from east to west passing zenith while Venus cannot do that.

Beautifully ringed Saturn is seen in the east close to the stars that make the tentacles of Scorpio. It is currently shifting westwards away from the tentacle stars in retrograde (opposite) motion until beginning August after which it will resume its normal eastward motion and will come again close to Scorpio’s tentacle stars by the end of October, by which time it will be close to the west horizon setting with the Sun. It will then disappear from the evening skies and reappear in the east after six months, similar to Jupiter because its orbit is outside that of Earth’s.

Mercury is normally very difficult to detect with naked eyes since it is always close to the Sun, however now it is currently high enough to be seen just before sunrise close to the red giant star Aldebaran in Taurus. The pair remain close while Mercury climbs to its highest elevation of 22 degrees on 24th June. It will remain high enough to be detectable until the first week of July.

The observation of the First Crescent will attract many observers to look up at the sky just after sunset towards the west. The first objects to strike the eyes will be the close Venus-Jupiter planet pair seen as extremely bright stars. New Moon is on 16 June when the Moon will be adjacent to the Sun and sets with the Sun, so it cannot be seen.

By the following day, 17 June, the Moon will have climbed 12 degrees so it can be far enough away from the Sun to seek out the First Crescent. However since the crescent will be quite slim and low near the horizon, so it will be quite a challenge to detect it in brightness of scattered light from the Sun. You will need a clear view of the horizon with clear skies without any clouds. Look in the area just above the west horizon directly below the two bright stars, the planets Venus and Jupiter, and just right of the position where the Sun will have set around 6:15 pm.

By 18 June the Moon will have climbed another 12 degrees so will be high enough and big enough to be seen. Again, look in the area of the sky as described above.

The more interesting aspect to observe is that all the planets and the Moon are ALWAYS found to lie close to an imaginary line running from east to west. This line is called the ECLIPTIC and is the path of the Sun in the sky. All planets are seen along the ecliptic because our solar system is a flat system with the all the planets orbiting the Sun in a flat plane. When we look at the ecliptic line in the sky we are looking along the plane of our solar system. This is similar to the thin path of the Milky Way that crosses the sky because the dense collection of stars in our Milky Way galaxy are all in a thick flat system like a plate.

Before the close approach in the sky (conjunction) of Venus and Jupiter on 30 June, there will be a remarkable sight in the sky two days after New Moon, from 19 to 21 June when the thin crescent Moon will also be close to Venus-Jupiter pair and will form very attractive shapes in the evening sky easily seen by many people. On 20th the crescent Moon will form a symmetric triangle while on 19th and 21st the crescent will be below and above the Venus Jupiter plane and along the ecliptic.

The Moon is New on June 16 and First Quarter on June 24, when it will be overhead at sunset and it will be in half shape. This is the best time to see the Moon through a telescope or binoculars because the shadows cast near the light-dark edge are long and sharp. This brings out the craters clearly into view. Full Moon will be on July 2 and Last Quarter on July 8.

This month’s sky map shows us that we can see nearly 18 constellations and asterisms. To see all of them you will need to be well away from city or town lights, in rural areas, where there is no light pollution. Marked alphabetically from A to R these are, from south to north, then east to west: A – Sagittarius the archer, B – Scorpius, C – Ara the alter, D – Triangulum Australe, the southern triangle, and E – the famous Southern Cross continuously pointing south. F – is the False Cross, G – is Vela, the sail, H – is the zodiacal constellation of Libra the scales of justice and I – is the long Hydra the snake. J is Virgo the virgin while K – is Leo the Lion. L - is Cancer the crab while M – is Hercules, N – is Bootes the herdsman and T – is the famous Big Dipper pointing north. P – is Ursa Major, the big bear while Q – is Draco the dragon. R – is the Little Dipper in Ursa Minor whose end star is the North Star but which we never see as it is below the horizon.

Among the bright stars marked ‘m’ to ‘s’ on the map are: ‘m’ – Alpha Centauri the closest star at a distance of 4.3 light years and ‘n’ – is Beta Centauri. ‘t’ - is red star Antares in the neck of Scorpius, ‘p’ – is Spica in Virgo while ‘q’ is the third brightest star Arcturus (the first and second brightest stars are respectively Sirius and Canopus will have set in the south west by 8 pm). ‘r’ – is Regulus in Leo while ‘s’ – is Procyon.

The full glory of the dense concentration of stars and dust can be seen in the Milky Way which stretches across the southern skies from southwest to southeast containing the constellations or asterisms C, D, E, F and G. It runs parallel to the zodiacal constellations A, B, H, J, K, L. June 21 is the Solstice, when the Sun starts its journey back towards the Equator from its northernmost position of 23.5 degrees at the Tropic of Cancer. This day marks the beginning of northern summers and southern winters with longest and shortest days in the respective hemispheres.

The International Space Station provides an eventful sight on 29th June when it will disappear in mid-flight when it is overhead. It will rise above the northwestern horizon at 7:42pm (19:42) and disappear after 5 minutes when it is almost overhead at 7:47pm. It disappears from sight suddenly because the sunlight can no longer fall on the satellite - that is, it enters the Earth’s shadow. For exact times at your location, go to www.heavens-above.com and log in with your coordinates to get the exact details of the times. At this website you can also enjoy a very realistic 3D visualization of the space station at: http://heavens-above.com/ISS_3D.aspx. Note that you will need a computer with a recent browser and fast graphics. Visit www.astronomyintanzania.or.tz for more astronomy information and details.