Survey Responses:- -TANZANIA
Astronomy as a Tourist Attraction
This month once again thousands of eyes will be turned upwards in the west horizon looking for a sacred celestial body. The Moon is the closest celestial body and continually in our eyes at night shifting position and changing shape as it orbits the Earth. The sight of one particular shape, the First Crescent marks the beginning of the month in many cultures that use the lunar calendar. Muslims will be awaiting the First Crescent to mark the end of Ramdhan fasting and celebrate Idd the following day. This month the First Crescent is expected to occur on either Thursday 17th or Friday 18th July. There is uncertainty in our ability to see the First Crescent because it is a very thin crescent that appears very close to the west horizon within the glowing atmosphere around the just set Sun.
The First Crescent is marked just after the New Moon, when the Moon has moved away from its alignment with the Sun. At New Moon, the Sun is behind the Moon, hence it is impossible to see the Moon because its night side is facing us. Immediately after that, since the Moon moves in its orbit around Earth, the Moon will no longer be in front of the Sun and will have moved slightly eastward, away from the Sun, as viewed from Earth. Once this happens, a small part of the daytime side of the Moon will come into view and forms a very thin crescent very close to the Sun.
When this crescent is visible from Earth, it is termed the First Crescent which will be thin and close to the horizon so will set within a short time. If the crescent is too thin it will be extremely difficult to see in the bright glow of the atmosphere around the setting Sun and will set before the sky has become dark enough.
The key factor for the First Crescent to be able to be seen is that the Moon should get enough time to move in its orbit after the New Moon so that is it sufficiently away from the Sun, and the crescent is large enough and high enough, for the sky to become dark and people have enough time to view it in the west horizon before the crescents gets too low. Since the crescent can only grow with time, once the First Crescent is detectable from one place on Earth, all other places in the world that are west of that location will reach nightfall later hence all other places to the west of the first observed location will also be able to view the First Crescent.
The New Moon this July is on Thursday 16th at 4 am in the morning Tanzania time. So by sunset on that day, 16th, the Moon will have had only about half a day to move in its orbit, which is not sufficient to move it away from the Sun. Hence at sunset on 16th, the crescent will be only 0.4% in size and only 5 degrees above the west horizon, which is practically impossible to see with naked eyes in the bright sunset sky. However, by the next day’s sunset on Friday 17 July, the First Crescent will be 2.4% in size and 16 degrees above the horizon and will set around 7.30 pm. This will allow sufficient time the sky to darken and for people to observe the First Crescent on Friday 17 July and we can expect the first day of Idd to be celebrated on Saturday 18th.
The brilliant Venus-Jupiter pair has changed places after coming closest at the beginning of the month. Venus shines ever brighter now as it moves closer to Earth in its orbit around the Sun. Through even a telescope or binoculars, Venus is seen as a thin crescent growing thinner by he day. However since the planet is getting closer to us, its angular size is getting bigger and bigger making it shine brightly in spite of its crescent getting thinner.
Venus and Jupiter are now further apart again and the crescent Moon will join the pair on 18 July forming a very attractive shape of an equilateral triangle. A bright star close to the Venus-Jupiter pair is Regulus, the brightest star of Leo constellation, but it is much fainter than the two planets. The planet pair will shift slowly downward towards the west horizon day by day and will disappear by mid next month.
Mercury enters the evening sky towards the end of this month. It is the closest planet to the Sun hence is always never far from the Sun and keeps close to the horizon. By 31 July it will be about 8 degrees above the west horizon at sunset hence you can set a challenge to detect a faint point in the bright horizon sky. By 7:45 it can be dark enough to be detected so the challenge can be who detects it first on the days following July 31. It will continue to rise in August, reaching a very high altitude of 24 degrees above the horizon at sunset and by that time it can definitely be seen. On 7 August Mercury will be seen close to Jupiter hence the bright planet will guide you to locate Mercury. Take time to see this mercurial planet since we are lucky to be in a location where it can be followed with the naked eyes.
Saturn keeps close to the tentacles of Scorpio and climbs high in the sky and can be seen almost over head at 8 pm. For further details of Tanzanian night skies see http://www.astronomyintanzania.or.tz
The Asteroid Day that was marked on 30 June is a new initiative to highlight the dangers of our planet being struck by a huge body with the potential of destroying large populations of life on Earth. There are a million of asteroids with the potential to destroy but only 10,000 have been discovered and are being tracked to alert us of their dangers. Hence there is a 100 times more effort that has to be put in to detent and monitor Near Earth Asteroids (NEO). Hence governments of the world need to be aware of this danger and urges people to sign a petition to support this action. Visit http://www.asteroidday.org/declaration for more information and support this movement.
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. Scorpius in 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. Scorpius is the only constellation that does full justice to its namesake, the scorpion and is unmistakable to even a casual stargazer. Below Scorpius, try to identify Sagittarius (the archer). This constellation marks the direction of the center 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 upto 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.
The International Space Station (ISS) is set to make a majestic crossing across the Tanzanian evening skies between 28th and 30th July, with the southern areas on 28th, coastal central areas seeing it on 29th, and western and northern parts seeing it on 30th July. Look up the exact times for your location using the websites http://www.heavens-above.com and http://spotthestation.nasa.gov
The following is a summary of interesting astronomical events during this year 2015 that can be observed by the public without the need of a telescope.
The events are described for positions in the sky and the times for viewers in Tanzania, or East Africa. You may read about some of these events in international media but some of these are not seen from Tanzania and the timings can be different.
The events are chronologically arranged by dates that they occur.
Ø Solar eclipses occur when our view of the Sun is blocked by the Moon during the daytime causing a small shadow of Moon to fall on Earth. The Moon is in between the Earth and the Sun.
Ø Lunar eclipses occur when the large shadow of Earth falls on the Moon. The Earth is in between the Sun and the Moon.
Ø Total eclipses occur when the shadow is dark, called umbra.
Ø Partial eclipses occur when the shadow is not completely dark (called penumbra) since some light falls in the shadow area.
Ø Exciting Note: Next year 2016, an annular solar eclipse passes through a 100 kilometer path across southern Tanzania on Sept 1, 2016. The whole of Tanzania will experience nearly 90 percent of the Sun being covered.
· Total Solar Eclipse, 20 Mar, North Pole, None visible in Tanzania
· Total Lunar Eclipse, 04 Apr, Pacific Ocean, None visible in Tanzania
· Partial Solar Eclipse, 13 Sep, South Pole, None visible in Tanzania
· Total Lunar Eclipse, 28 Sep, Atlantic Ocean, Partial eclipse visible in Tanzania
Ø Meteors are light streaks in the night sky that look like a shooting star. The light is emitted by burning in the atmosphere of tiny dust grains from coming from space. Sometimes larger particles can strike the atmosphere and the light glows much more brightly or even explodes known as bolides.
Ø Meteor showers are formed when high concentrations of dust from past comets trails and asteroids strike Earth at the same time causing many meteors in a short period.
· Quadrantid, Weak, North, Jan 3-4, Big Dipper, Moon too bright
· Lyrids, Weak, North, Apr 22-23, Cygnus, Vega(Alpha Lyrae) Moon too bright
· Eta Aquarids, Strong-60 met/hr, Equator, May 5-6, Aquarius, no Moon so meteors can be detected
· Delta Aquarids, Weak, near Equator, Jul 28-29, Fomalhaut-pegasus square, Moon too bright
· Perseids, Strong- 60 met/hr, North, Aug 12-13, Perseus, No Moon so meteors can be detected
· Draconids, Weak North Oct 8-9, Little Dipper, Moon too bright
· Orinids, Weak, Equator, Oct 21-22, Orion, Moon sets early so meteors can be detected, (additional - Venus-Jupiter-Mars in morning sky)
· Taurids, Weak, Equator, Nov 5-6, Taurus, Quarter Moon too bright in morning sky
· Leonids, Ok, Equator, Nov 17-18, Leo, Quarter Moon sets early so meteors can be detected
· Geminids, VeryStrong-120 met/hr, Equator, Dec 13-14, Gemini, Crescent Moon sets early so meteors can be detected
· Ursida, Weak, North, Dec 22-23, Little Dipper, Moon too bright
Ø Planet opposition occurs when the full face of the planet is lit by sunlight with the planet on one side (east side) of Earth while the Sun is on the opposite side (west). So a brightly shining planet rises from the east at sunset.
Ø Close approach of planets in the night sky occurs when their lines of sight as viewed from Earth are separated by very small angles. Hence though they appear to be close to each other in the night sky, it does not mean that they are actually close to each other in space. All planets are separated by millions of kilometers of space in their orbits around the Sun.
· VENUS and MERCURY close, Jan 10, they will be seen close together 20 degrees above the west horizon just after sunset. Start watching from now up to mid-January as Mercury approaches Venus from below and comes closest on Jan 10 within one degree and then moves down again away from Venus. Mercury is a faint point and can be a challenge to detect, while Venus will be bright. Venus will continue to rise in the sky in the following months rising to 40 degrees in June and then quickly coming down to the horizon by August.
· JUPITER at opposition, Feb 7, brilliantly bright Jupiter will be seen rising in the east just as the sun sets in the west. It will remain in the evening night sky for the next six months moving gradually westwards.
· VENUS and MARS close, Feb 21, they will be seen close together 20 degrees above the west horizon just after sunset. Start watching from mid-February up to the end of February as first Venus approaches Mars from below and comes closest on Feb 21 within half a degree and then moves up away from Mars. Mars is a tiny red point while Venus will be very bright yellow.
· Uranus and VENUS close, Mar 4, though Uranus cannot be seen easily since it is very faint, it can be seen with naked eyes only in darkest skies since it is just at the limit of naked eye visibility. However this is an excellent opportunity for telescope observation of the planet (even through small telescopes) since it can be located within a tenth of a degree from Venus on Mar 4 so it can be easy to catch even in a small telescope. The pair will be 30 degrees above the horizon at sunset with Uranus approaching Venus from above coming closest to Venus within a tenth of a degree on Mar 4 and passing below on following days.
· Uranus and MARS close, Mar 11, presents another opportunity to locate the faint Uranus through even a small telescope when it comes closest to Mars to within half a degree. Mars is a faint red star and can be identified among the other stars.
· SATURN at opposition, May 24, sharply shining Saturn will be seen rising in the east just as the sun sets in the west. It will remain in the evening night sky for the next six months moving gradually westwards.
· JUPITER and VENUS close, Jun 30, two brilliant planets will shine as bright stars in the evening sky close together 40 degrees above the in the west soon after sunset. Start watching from mid-June to mid-July as Jupiter approaches Venus from above and comes closest on June 30 within half a degree and then moves down away from Venus. This will be an extremely noticeable event since many people will see two extremely bright objects close in the sky for more than a month.
· JUPITER and MERCURY close, Aug 7, seen 15 degrees above the western horizon at sunset, with Venus 10 degrees to the left below the Jupiter-Mercury pair.
· JUPITER and MARS close, Oct 18 they will be seen close together 30 degrees above the east horizon just before sunrise. Start watching from beginning of October to mid-October Jupiter first approaches Mars from below and comes closest on Oct 18 within quarter of a degree and then moves up away from Mars. Mars is a tiny red point while Jupiter will be very bright white.
· JUPITER and VENUS close, Oct 26, two extremely brilliant stars, Venus and Jupiter will be seen close together 40 degrees above the east horizon just before sunrise. Before sunrise they will be seen closer to the east horizon. Start watching from mid-October up to the end of October as first Jupiter approaches Venus from below and comes closest on Oct 26 within half a degree and then moves up away from Venus. This will be an extremely noticeable event especially for early rises since they will be seeing two extremely bright objects in the sky for almost the whole of October.
· VENUS and MARS close, Nov 3, they will be seen close together 45 degrees above the east horizon just before sunrise. They will come closest to within half a degree as Mars approaches Venus from below and then moves up away from Venus.
· VENUS and SATURN close, Jan 9 2016. They will be seen 35 degrees above the western horizon at sunset and will come closest to each other within a tenth of a degree.
Ø Full Moon occurs when Moon is on one side (east) of Earth while Sun is on the opposite (west) side. Hence sunlight is striking the Moon full face and the full bright circle of Moon is seen in the east from sunset onwards.
Ø New Moon occurs when Moon is viewed with Sun directly behind it hence dark (night) side of Moon is facing us and dark face is in the west horizon at sunset.
Ø Crescent Moon occurs immediately after New Moon once some sunlight is able to strike the Moon but we see only a thin part of the lower side of the Moon. Crescent Moon are seen low in the west horizon at sunset or low in the east horizon at sunrise.
Ø Half Moon occurs when we see the Moon as a half circle and is . It is actually called First Quarter or Last Quarter since it occurs during first or last quarter of the Moon’s cycle around Earth.
Ø Gibbous Moon is shaped like an oval and occurs between half Moon and Full Moon.
· Full Moon, Jan 5
· New Moon, Jan 20
· Crescent Moon close to MERCURY Jan 21, will be seen 12 degrees above the western horizon at sunset with Moon 2 degrees below Mercury.
· Crescent Moon close to VENUS and MARS Jan 22, will be seen 25 degrees above the western horizon at sunset with Moon in between Mars above and Venus below 10 degrees apart.
· Crescent Moon close to MARS Jan 23, will be seen 40 degrees above the western horizon at sunset with Moon 2 degrees above Mars.
· Full Moon, Feb 4
· Full Moon close to JUPITER Feb 4, will be seen rising in the east horizon soon after sunset and will be visible throughout the night, slowly shifting westwards through the night
· New Moon, Feb 19
· Crescent Moon close to VENUS-MARS pair, Feb 20, will be seen 20 degrees above the western horizon at sunset with the planet pair 5 degrees above crescent Venus. The trio will slowly drop lower through the night and set after about an hour.
· Almost full Moon close to JUPITER, Mar 3, will be seen rising above the east horizon at sunset and the pair will be seen slowly shifting westwards through the night.
· Full Moon, Mar 5
· New Moon, Mar 20
· Crescent Moon between Venus and Mars, Mar 22, seen at 25 degrees above the western horizon at sunset, with Venus 5 degrees above and Mars 10 degrees below the crescent Moon. The trio will slowly drop lower through the night and set after a couple of hours.
· Half Moon close to JUPITER, Mar 30, will be seen near the zenith from sunset, shifting westwards through the night.
· Full Moon, Apr 4
· New Moon, Apr 18
· Crescent Moon close to VENUS, Apr 21, will be seen 35 degrees above the western horizon at sunset with Venus 10 degrees to the right of crescent Moon. The pair will slowly drop lower through the night and set after a few hours.
· Half Moon close to JUPITER, Apr 26, will be seen near zenith 5 degrees apart with the pair shifting westwards through the night and set below the western horizon soon after midnight.
· Full Moon, May 4
· New Moon, May 18
· Crescent Moon close to VENUS, May 21, seen 40 degrees above the western horizon at sunset. The pair will slowly drop lower through the night and set after a few hours.
· Half Moon close to JUPITER, May 23, 24 seen close to zenith overhead about 10 degrees apart. They will shift slowly westwards and set before midnight.
· Full Moon close to SATURN, Jun 1, with the pair rising above the eastern horizon at sunset. They are 2 degrees apart and shift westwards throughout the night.
· Full Moon, Jun 2
· New Moon, Jun 16
· Crescent Moon between JUPITER-VENUS pair, Jun 20, seen 45 degrees above western horizon at sunset, with Moon 5 degrees apart from the planet pair. The trio will slowly drop lower through the night and set after a few hours.
· Almost full Moon and SATURN close, Jun 28, seen half way up the eastern sky at sunset with the pair 5 degrees apart and shifting slowly westwards through the night.
· Crescent Moon close to VENUS-JUPITER pair, Jul 18, seen 30 degrees above the western horizon at sunset forming a triangle 5 degrees apart. The trio drops slowly, and sets below the horizon after a couple of hours.
· Gibbous (oval) Moon close to SATURN, July 26, near zenith 65 degrees above eastern horizon at sunset. The pair shifts slowly westwards and sets after midnight.
· Full Moon, Jul 31
· New Moon, Aug 14
· Half Moon and SATURN close, Aug 22, seen close to zenith overhead two degrees apart. The pair shifts slowly westwards through the night setting close to midnight.
· Full Moon, Aug 29
· New Moon, Sep 13
· Half Moon and SATURN close, Sep 19, seen close to zenith overhead two degrees apart. The pair shifts slowly westwards through the night setting close to midnight.
· Full Moon, Sep 28
· New Moon, Oct 13
· Crescent Moon and SATURN close, Oct 16, seen 40 degrees above western horizon at sunset 2 degrees apart. The pair sets slowly below the western horizon after a few hours.
· Full Moon, Oct 27
· New Moon, Nov 11
· Crescent Moon and SATURN close, Nov 13, seen 20 degrees above western horizon at sunset with crescent 5 degrees above Saturn. The pair sets after an hour.
· Full Moon, Nov 26
· New Moon, Dec 11
· Full Moon, Dec 25
· New Moon, Jan 10 2016
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Dr Noorali Jiwaji SPoC for Tanzania for IYA2009