October Night skies over Tanzania 2013

October Night Skies Over Tanzania


Viewing the first crescent Moon will be of interest for those following the Idd el Hajj occasion since it is celebrated as a national holiday 10 days after the sighting of the first crescent Moon. The astronomical New Moon occurs on 5th October 2013 at 3:35 a.m. By sunset at 6:14 pm, it will still be very close to the setting Sun, less than 6 degrees above the western horizon.  This can make the New Moon go beyond the limit of naked eye visibility.  See the first two simulations of the views western sky at sunset at 6:15 pm on that day, and 10 minutes later at 6:25 pm.  Hence the first crescent can be expected to be seen the next day, on 6th October 2013, when it will be at of 18 degrees elevation.  It will also be of sufficient size and brightness and visible until 7 pm when the sky will be dark enough to see the first crescent where the sky is clear.  See the third simulation below.


October 5, New Moon at Sunset at 6.15 pm at 5 degrees above the West horizon

October 5, New Moon 10 minutes after Sunset at 6.25 pm at 3 degrees above the West horizon

October 6, First Crescent at Sunset at 6.15 pm at 17 degrees above the West horizon

Between October 6 and 9, the crescent Moon will be accompanied in the western sky with three planets – Mercury, Saturn and Venus.  On October 6, the crescent Moon will below the close pair of Mercury and Saturn while on October 7 the crescent will be above that planet pair. Mercury and Saturn are seen as fine bright points that do not twinkle, which distinguishes them from any nearby stars which twinkle significantly.  This month is the last available for viewing Saturn since its elevation is decreasing day by day and will be lost from evening view by the end of the month.  Fast moving Mercury will also be similarly lost from view even before the end of the month.


The most beautiful sight awaits us on October 8 when a big bright crescent will be close and to the left of brilliant Venus.  It will be a memorable view with two extremely attractive heavenly bodies coming together in our line of sight.  The couple will be visible until nearly 9 pm but start observing by 7 pm so that you can identify the other close pair of Saturn and Mercury below, at a similarly aligned angle. Do not miss this opportunity.  Through a telescope you will see Venus as a half disk shape, with only half of its illuminated face visible from our view since its orbit is inside that our Earth’s.


Venus continues to rise and shift its position in the sky relative to the stationary stars.  This month this shifting effect can be followed with Venus and the red giant star Antares (marked E in the sky map).  These two are moving towards each other now, and by October 17 they will be close together.  After that they will move apart again with Venus rising higher and higher in the sky as it continues in its orbit around the Sun.  At the same time the stationary Antares is shifting slowly downwards in the sky due the revolution of the Earth around the Sun.  Venus will reach a maximum height of 45 degrees above the horizon at sunset on 11 November, 2013. 


October 17 is also useful to note for observation of planet Uranus when it will be close to the Moon.  This distant planet, next after Saturn in distance from the Sun, is just outside our naked eye limit of viewing, so you will need a telescope to catch it. More details for viewing the planets can be found at the Astronomy In Tanzania website: http://www.AstronomyInTanzania.or.tz


The phases of the Moon this month are: New Moon October 5, First Quarter October 12, Full Moon October 19 and Third Quarter October 27.



This month at midday on October 11, we will also witness the disappearance of all shadows at 12:10 pm, when the Sun will be exactly overhead.  Follow the shadows of upright objects right from now and you will see that they are quite short and getting even shorter by the day.  This will culminate on October 11 when shadows will be exactly under the object.  Such a situation happens only twice each year, with the next event in mid-March.



On Sunday evening around 8 pm September 29, many people who were outdoors at the time witnessed a strange sight of a slowly growing circular cloud with a star like point in its middle.  It rose as a small circular patch from the south horizon and rose for about four minutes and disappeared in overhead sky.  It amazed many people in the city and other parts of the country, and in fact was seen over most of Africa and the Indian Ocean. See picture below taken by an amateur observer in  Reunion Island in the  Indian Ocean:



Many people feared the worst that we had a visit from outer space!  However it turned out to be a spacecraft (Space X’s Falcon9 v1.1 rocket) that had just been launched from the US west coast an hour earlier.  A used stage of the rocket ejected its fuel, which formed a cloud.  Sunlight from the Sun which was just below the horizon was able to reach the cloud while we were in darkness.  Hence the cloud and the spacecraft became clearly visible.  Many satellites that orbit our earth can be seen in the evening or dawn skies when the Sun is still below the horizon and sunlight can still reach the satellites that orbit a few hundred kilometers above us. 


Light reflected from such satellites makes them appear as slowly moving stars.  The International Space Station (ISS) is the most famous and brightest such satellite which looks like a brilliant moving star. You can find which satellites are visible in your area from the website http://www.heavens-above.com. The ISS will make a very bright journey across our skies next month, on November 2.  It will cross the through the middle of the sky, rising from the northwest horizon at 7:18 pm.  It will move slowly across the sky over the next 7 minutes like a brilliant star, disappearing in the southeast horizon at 7:25 pm.  Two days later, on November 4 the bright spacecraft will again make a pass in our bright skies of the setting Sun in the West, passing very close to Venus at 7:20 pm.  It will be a good challenge to make out this bright satellite near brilliant Venus.  See charts below for the passage of the ISS on these two days across the sky.


ISS Nov 2 PassSkyChart2

ISS Nov 4 PassSkyChart2

Comet ISON a significantly large comet which has been attracted for  the first time by our Sun to come in  from the extreme edge of our Solar  System is set to turn around the Sun at the  beginning  of  November.  At the moment it is still a dim telescopic object visible  in the dawn sky near the planet Mars.  However, if it makes the turn around the Sun safely without breaking up, then at the beginning  of November, it can become one of  the largest comets in history.  Keep  a lookout on  http://www.AstronomyInTanzania.or.tz for further information close to November.



The Milky Way runs from southwest to northeast is a as a band of numerous stars can be recognized even in brightly lit city skies. It stretches from the tail of Scorpio in the south, through Sagittarius to Cygnus constellation in the north.  The Milky Way is our own galaxy within which we live.  Our Solar System is located in one of the arms of the flat spiral shape of our galaxy, one third of the way from its edge.  While looking at the Sagittarius constellation you are actually looking towards the centre of our glaxay.


This month we can see two other galaxies with our naked eyes, though you will need to be well away from city lights. With a pair of binoculars the shape of the cloudy patch identified. The Andromeda galaxy, marked T near the north and close to the Square of Pegasus marked S, has the same flat spiral shape as our own Milky Way galaxy.  It is nearly 2 million light years away from us (i.e. light travelling at 300 thousand kilometers per second takes 2 million years to reach us!).  So the Andromeda galaxy is the farthest object visible with our naked eyes.  A sight worth going out to look for!


The other galaxy is our satellite galaxy, the Small Megallenic Cloud, closest to us at 500 thousand light years away.  It is marked U towards the south in the sky map.



The bright stars in the early evening sky this month are marked in the sky map and can be identified as follows: A is Fomalhaut in the overhead sky towards the south, while towards the north the star marked B is Altair. C, which is close to the north is Deneb in Cygnus constellation while E is Antares, a red giant star in Scorpio.  The star marked H, rising in the south east, is Achernar.



November 3 is a day to mark vividly in your calendar since a major solar eclipse takes place soon after noon.  On that day, the dark shadow of the Moon will show up with the Sun begin to covered from just after 2 pm.  Maximum coverage of nearly 70% for mid-Tanzania, will be just before 4 pm, and by 5:30 pm the whole face of the Sun will become visible again.  Visit these websites that provide useful information about the eclipse:






The total eclipse path for this event will pass through northern Uganda, Kenya and ending in Ethiopia.  You can visit this site if you want to visit the total eclipse site in northern Kenya: http://rotec.rotarynairobi.org/packages.htm .  Prepare yourself with special eclipse glasses to see this spectacle, or you can also use Welder’s Glass No. 14.  



Did you know that on September 1, 2016 there will be an annular solar eclipse passing through Tanzania, centered over the south of our country!