galileannightsoctober2009

Galilean Nights October 2009

Galilean Night Skies in October

By Dr. N. T. Jiwaji

ntjiwaji@yahoo.com

October Galilean Nights Sky Map - Click on the map to get a larger map

The International Year of Astronomy celebrates Galileo’s contribution to a revolution in Science and Astronomy by holding stargazing sessions all over the world in an activity dubbed Galilean Nights during the evenings of Thursday 22^nd October, Friday 23^rd and finally on Saturday 24^th October. We will be able to witness with our own eyes what Galileo saw when he first pointed a very modest telescope that magnified 30 times and was able to see the rough pockmarked face of the Moon. He attributed this roughness to mountains and craters and broke long held belief that the Moon was smooth.

Galileo Galilei

Galileo was also the first to observe Jupiter through a telescope and saw the four moons named the “Galilean Moons” which are the most enjoyed by star watchers even today. The positioning of the Galilean Moons in a line extending on either side of the ball of the planet and the occasional disappearance of the moons behind the face of the planet led him to accept fully Kepler’s work based on the Copernican model of planets revolving around the Sun. This stand eventually led to his confrontation with traditional belief by the Church which forced a confession from him that the Earth was stationary. Only recently in 2000 Pope John Paul pardoned Galileo and confirmed his stand that the earth and the planets revolved around the Sun.

We are now celebrating 400 years since Galileo’s first view of the heavenly bodies by marking this year as the International Year of Astronomy. One of the aims of this year is to get millions of people all over the world to be able to see the Moon and planets and the sky through a telescope. One such event already took place in April this year named 100 Hours of Astronomy, with thousands of stargazing events held all over the world. In Tanzania two events were held, one at Morogoro and one in Dar es Salaam.

Galilean Nights

The opportunity has once again been presented by a similar event called the Galilean Nights with even more events being held all over the world. In Tanzania, the Galilean Nights events are being coordinated by Mr Mponda Malozo and expected to be held all over Tanzania. Events have already been registered in Arusha, Dar es Salaam and Morogoro. In Arusha the event will be held in Monduli organized by UNAWE Tanzania under Essau Loisujaki. Four events are planned in Dar es Salaam. One is at Azania Secondary School conducted by school teachers and Jiwaji, another at the Stakishari football ground in Ukonga organized by IYA Tanzania under Mponda Malozo, a third at Mbezi Sacuveda organized by UNAWE Tanzania under Joeline Ezekiel and the fourth one at Sama Learning Centre in Sinza organized by Sinza Astronomical Club under Beniel Seka. The event in Morogoro is registered to take place at Solomoni Mahlangu Campus SUA organized by EWAT under Deodatus Kiriba Dr Karugila.

With many telescopes now distributed to various schools, clubs and individuals, many more events are expected to be registered in many towns in Tanzania. For more details visit the website: http://www.galileannights.org/events/event_country_tanzania.html

Jupiter

During the three day Galilean Nights observing period from 22^nd to 24^th October, we will be able to see these two heavenly bodies, the Moon and Jupiter shining brightly in the early evening night sky. Jupiter shines extremely brightly in the overhead sky visible soon after the sun sets at 6:15 pm. Through a telescope, you should be able to see the four moons lined up on either side of the planet. If you watch over a couple of hours you will even see a shift in the position of the moons of Jupiter as they move in their orbits around the planet. You should also be able to make out parallel bands on the planet’s disk. These are the thick belts of clouds that circle Jupiter.

Moon

The Moon will be seen midway up the western sky soon after sunset on 22^nd shifting towards Jupiter on the following days. The shape (i.e. its phase) will be a thick crescent on 22^nd which will change to almost half phase by 24^th October. These are the best days to observe the moon since the Sunshine is falling on the Moon’s surface at a steep angle which allows deep shadows to form in the craters and mountains of the Moon. Galileo was even able to estimate the depth of craters and heights of the mountains on the Moon from his observations 400 years ago!

While watching the Moon from 22^nd October, you can imagine the Sun which has gone below the horizon shining its light from under us. The sunlight striking from below lights up only the bottom part of the Moon’s globe so we see only a small part that is towards us and hence we see a crescent. Over the next few days, as the Moon goes higher in the sky, more and more of the sun lighted half of the Moon is seen so we see a bigger and bigger and bigger crescent until it becomes half phase. While watching the Moon during the Galilean night you will be able to imagine the motion of the Moon around us.

Constellations

The evening sky is worth watching for prominent stars and galaxies. Over the next few months the night sky will show four galaxies visible to the naked eyes. The obvious one is our own “Milky Way” galaxy which we see from inside it as a bright band of myriads of stars and interstellar dust in cloudy patches known as nebulae. The Milky Way band stretches north, in the W shaped Cassiopeia, through Cygnus, the large northern bird, on to Sagittarius the archer and through the tail of Scorpio. The portion of the Milky Way close to Sagittarius appears as a cloud that is not a real cloud but nebulae of dense interstellar matter that is hiding from our view a powerhouse that is a supermassive blackhole at the center of the Milky Way galaxy. The eastern sky has two “birds”; one to the northeast, where you will see the Cygnus with its body and wings making a wide cross, while in the southeast you will see the smaller bird Grus with its head twisted sideways. Try to become familiar with the brightest stars by their names and relative locations.

The zodiacal constellations shown on the map have been moving slowly across the sky map as the months progress. On average, one new constellation disappears from the western sky and a new one appears in the east. This tells us that the earth is slowly moving around the Sun one twelfth of the way forward every month. If you were to watch the solar system from a point very high above the North Pole, we would see that the earth revolves anticlockwise around the sun. This direction of revolution around the sun is the same as the rotation of the earth about its own axis.

Milky Way

Our Milky Way galaxy is an immense flat collection of 300 billion stars in a spiral formation. It is about 100,000 light-years across and 1,000 light years thick. Which means light, traveling at 300,000 kilometers every second would take 100,000 years to cross from one end to the other! All the stars that we can see with our naked eyes are part of our own Milky Way galaxy which is seen as a broad band of stars stretching from the south to north through the tail of Scorpio, Sagittarius, Cygnus and Cassiopeia. We see this broad band of dense collection of stars which is also called the Milky Way since we are looking from inside along the flat compact collection of stars. Anywhere away from that will be very few stars. The centre of the Milky Way Galaxy is in the direction of Sagittarius.

Galaxies

Our closest neighbor galaxy, the “Small Megallenic Cloud” (SMC) 500,000 light-years away is relatively quite close to us. It is visible as a patch of brightness close to the south horizon. Close to it is the “Large Megallenic Cloud” galaxy but is not yet visible this month. Four times farther away at 2 million light years is the next closest galaxy, the Andromeda galaxy, making it the farthest object that can be seen with our naked eyes. It can be seen near the Square of Pegasus close to the north eastern horizon in the early evening. Through a powerful telescope it is seen as spiral similar to the shape of our Milky Way galaxy. Galaxies contain around a hundred billion light stars kept revolving together around a super-massive black hole.

Satellites

In the couple of hours after sunset, it is the best time to detect moving satellites in the overhead skies. These are seen as tiny points drifting slowly across the sky. If you lie on the ground and scan the skies without straining your neck, you are bound to detect some moving points which are the satellites. However it is much more pleasing if you can also put a name to the satellite. This can be done using information from the website: http://heavens-above.com/ with a dash connecting the two words. Remember to set your location by entering your latitude and longitude. I have summarized here some of the brighter satellites which will be seen during the three days of the Galilean Nights. The timing should be crosschecked at the heavens-above website.

On 22^nd the Cosmos 2297 Rocket will be seen just after 8 pm rising from the south and will pass very close to Jupiter and will disappear from view suddenly soon after that.. On 23^rd October you will see three satellites crossing the sky. The GPS 2-14 Rocket1 will be seen rising in the north west soon after quarter to seven and will cross the whole sky overhead for about 8 minutes disappearing in the east horizon. At 7 pm the Lacrosse 5 will rise in the north west and sets in the north east horizon ten minutes later. Soon after 7:45 you will see the Cosmos 2297 Rocket again rising in the south and passes even closer to Jupiter and will disappear from view suddenly in the north 15 minutes later. On October 24^th you should be able to see four satellites. The Cosmos 660 Rocket will rise in the south at about 7:10 pm and will cross the overhead skies passing close to Jupiter and set in the opposite horizon five minutes later. The third pass is that of the GPS 2-04 Rocket1 which will rise in the north west soon after 7:30 pm and will cross the overhead skies and will disappear in the overhead skies four minutes later. The fourth satellite is the Cosmos 2297 Rocket which will rise in the south soon after 7:30 pm and will cross the whole sky over head passing close to Jupiter and disappearing in the north 10 minutes later.

The International Space Station though far more brilliant than the other satellites, is a bit of a disappointment this month with a low horizon showing on 31^st October and 1^st November. On 31^st it will rise in the south just after 6:30 pm and will rise to about 30 degrees in the south east and will set in the east five minutes later. On 1^st November it will hug the opposite north west horizon after rising in the south west just before 7pm and will rise to about 30 degrees in the north west and will set in the north five minutes later.

Enjoy the Galilean Nights this October.