July Night Skies over Tanzania

By Dr. N. T. Jiwaji,

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Download sky map here

Download Galileoscope picture here

Download sunspot picture here

Download sunspots and CME here

Download other sunspots picture here

After several years of quiet with a “deep minimum” in 2009 in its 11-year cycle, the Sun is now waking up, with colossal energies breaking through the surface in areas seen from the Earth as SUNSPOTS. 

If you were lucky to witness the event of century, the “Transit of Venus” event on June 6, and saw the tiny dot of Venus crossing the face of the Sun, then you can easily see the sunspots that can be nearly six times bigger than that dot of Venus. 

Sunspots can be seen during the daytime using a pair of solar glasses or by projecting the image of the Sun through a simple telescope, such as a Galileoscope, or through a pinhole. The pictures shows the setup of the Galieoscope and sunspots that I viewed, compared with the that from the NASA website www.spaceweather.com (the Galileoscope image is inverted by the telescope lenses). 

Sunspots are huge areas (up to 100,000 km across) on the surface of the Sun that are about 2,000 degrees centigrade cooler the rest of the surface of the Sun, which is around 6,000 degrees centigrade. Since visible light is only emitted around 6,000 degrees centigrade, the sunspots produce infrared radiation, which our eyes cannot see. Hence, the spots appear completely dark compared to rest of the extremely bright surface of the Sun. 

Sunspots are areas through which extremely high magnetic fields come out and re-enter at another sunspot, comparable to the field lines in an ordinary magnet from north to south poles. The fast moving positively charged hydrogen produces magnetic fields in the Sun and helium nuclei stripped of electrons (known as plasma).  

The Sun’s energy if first produced at its centre which is at more than 10 million degrees centigrade and at extremely high pressure. Under these conditions, nuclear fusion of hydrogen and helium nuclei produces extremely high energy gamma radiation. These gamma-rays take several thousand years to pass through the dense core of the Sun and hence degenerate huge amount of visible light at the surface which is at 6,000 degrees centigrade. 

The energy of the fast moving plasma is normally confined within the magnetic field lines that connect from one sunspot to the other. However, when the energy is extremely high, the magnetic field lines break, and cosmic particles are thrown out into space at speeds close to that of light. Such explosions are known as coronal mass ejections or CMEs (see picture). 

CMEs are very harmful to humans but fortunately we are protected from these cosmic particles by the Earth’s own magnetic field that forms a protective envelope. This deflects the harmful particles towards the north and south poles and cause a night glow called aurora. However, when CMEs are directly aimed at the Earth they manage to penetrate partly and can harm electronic systems of orbiting spacecraft as well as on the ground. 

The current increase in the number of sunspots after several years of quiet is expected to produce much higher energy CMEs that can be even more harmful to increasing number of communications and research spacecraft as well as our modern lifestyle, which depends on electricity and electronics. 

To counter this threat, a new field of space weather is used to understand, monitor, and predict the activity of the Sun. Since the Sun rotates about once every 25 days, the sunspots also shift and their numbers and positions change continuously. You can check the status of the sun on the NASA website www.spaceweather.com, which is updated regularly, to know the current status of the Sun. 

The night skies hold some interesting views also with crisp, clear skies, rain-free since the beginning of the year. Two planets, Saturn and Mars can be seen overhead. The Virgo constellation is near its brightest star Spica. Saturn is far from the Sun so it does not show noticeable movement but Mars, being closer to the Sun, moves faster. Hence, Mars shifts its position noticeably day by day and approaches Saturn and Spica. The three will be close together and in line by August 14. Saturn shows off its beautiful set of flat rings that surround the planet since the ring plane is tilted towards us. 

The New Moon on July 19 will have ushered in the holy month of Ramadhan by Saturday 21 after the sighting of a sufficiently high Moon in the bright western skies after soon after sunset. Quarter phase with half shape will be on June 27, a time that is best for viewing the Moon’s craters. Full Moon will be on August 3rd while the next New Moon that will be on August 17 will be just at the limit of viewing by August 18which can mark the end of Ramadhan.

The southern skies are filled with very bright stars that would be hard to hide! The north and south direction pointers, that is the Big Dipper and the Southern Cross, are still high enough in the evening skies and can be used to mark the north-south direction very well. Scorpio is the dominant constellation this month, occupying the overhead evening sky with its three stars forming its tentacles, the red star Antares in its neck, and a long winding tail that ends in a close pair forming the sting. Scorpio is the only constellation that does full justice to its namesake, the scorpion and is unmistakable to even a casual stargazer. Use this opportunity to start (or continue) your stargazing hobby by independently identifying a constellation!  

Below Scorpius, try to identify Sagittarius (the archer). This constellation marks the direction of the centre of our Milky Way galaxy and you will notice dense concentration of stars here. The band marking the Milky Way contains numerous stars and dust patches and stretches from the southwest, passing through the Southern Cross and Sagittarius and up to Cygnus (the swan) in the northeast. Leo (the lion) with its distinctive inverted question mark head is low in the western horizon and will be lost after this month.

Among the brightest stars noticeable in the July skies are: Alpha and Beta Centauri in the south form the pair that points continuously towards the Southern Cross; the fourth brightest star Arcturus is overhead towards the north, and the fifth brightest star Vega rises in the northeast. Other bright stars you will easily notice are Altair which rises in the east and Spica, the brightest star in the Virgo constellation can be seen almost overhead towards the west.

Among the visible satellites, we will have a clear view of the newly installed Chinese space station Tiangong on August 18 when it crosses right across the exact middle of the sky from rising in the southwest at 6:39 pm, reaching maximum altitude at 6:42 pm and setting in the northeast at 6:45 pm having taken 6 minutes to cross the sky from horizon to horizon. For the ISS it is best to consult the website www.heavens-above.com nearer to August 4 when it will also cross the sky from about 7:06 pm in the southwest and setting 7 minutes later at around 7:13 pm in the northeast. Visit the website www.astronomyintanzania.or.tz for more details and information about astronomy in Tanzania.

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