Categotry Archives: Uncategorized

by

Introduction to Astronomy Course

Categories: Education, Members, Uncategorized, Tags: , , , , ,

If you are interested in Astronomy and have often wondered how you could learn more, the Duke University is offering a free course via an on-line medium called Coursera.

This innovative educational network of Universities providing free courses from a broad range of subjects and topics. The Coursera web site describes themselves as “…a social entrepreneurship company that partners with the top universities in the world to offer courses online for anyone to take, for free. We envision a future where the top universities are educating not only thousands of students, but millions. Our technology enables the best professors to teach tens or hundreds of thousands of students.Through this, we hope to give everyone access to the world-class education that has so far been available only to a select few. We want to empower people with education that will improve their lives, the lives of their families, and the communities they live in.”

The course that is of the greatest interest to us is the “Introduction to Astronomy” course provided by Duke University, North Carolina. In this class, “we will be studying, quite literally, everything in the universe.  We will start with “classical” astronomy, describing the night sky and organizing what we see as was done in ancient times.  We will then embark on a journey, starting here on Earth and progressing outward, to study the Solar system, the Milky Way galaxy, and the wonderful and strange objects we observe in deep space, such as black holes, quasars, and supernovae.  We will end with some discussion of what scientists know today about the universe as a whole.  Along the way we will introduce some of the methods, theoretical and experimental, that have been used to understand all of this, from Newton’s laws, through our understanding of light and matter, to Einstein’s theory of relativity, and from Galileo’s telescope to WMAP.”

This nine week course is 100% on-line making it accessible to virtually everyone who has access to the internet. Requiring a medium level of mathematical and physics knowledge is the only prerequisite, with a certificate of completion offered at the successful completion of the course. The availability of free education is quickly becoming a thing of the past. With Coursera offering this opportunity for free education world wide there is an incentive for many students and would be students to continue further education throughout their life.

by

Before & After the Solar Eclipse Cairns 2012

Categories: Education, Members, Uncategorized, Tags: , , , ,

By Dan Crowley

After arriving at Cairns on the Monday night, we rose early on Tuesday morning to view the eastern horizon from our hotel room. We had specially booked this room with the intention of setting up our cameras on the balcony and waiting in comfort for the eclipse to unfold. Before sunrise, the dark sky reveal only a few stars directly overhead. To the east a mountain stood between us and the sun. Although not an ideal location, the determined altitude of the sun at totality being 14 degrees would theoretically place the sun  above the crest of the small volcanic landscape. The unpredictable and threatening aspect of the setting was the cloud cover that hung perpetually over the hills. As the sun began to rise we were not able to find its position due to being completely blanketed by black stormy clouds. A small gap appeared intermittently allowing sun beams to radiate onto the buildings along the wharf.

As part of our contingency plan, we had a day before the eclipse to research the weather conditions and possible alternative locations. Some associates and friends that we had dined with the previous night elected to seek out a location near their accommodation. They decided on Trinity Beach being twenty kilometres north of Cairns CBD it provided good veiw of the ocean and was not far from their caravan park. The only problem was it was one of the popular locations for film crews and organised groups to assemble. These suburban locales were closed off to traffic an hour before totality so as to limit the traffic into the area. We thought more options would make themselves known once we drove further north. Having the whole day ahead of us, we journeyed north along the Captain Cook Highway, passing Palm Cove and Port Douglas along a stretch of road that closely passes the ocean beaches with their mixture of sedimentary sandstone and igneous granite rock facings. We found a number of good possibilities with good parking close to the beach and clear easterly views of the ocean. Stopping at a few of these locations, we checked our bearings with our smart phone compass and declared this area to be our best option for the eclipse morning. The rest of the day was filled with visits to the Daintree Discovery Centre and a drive to the furthest northern point on the sealed road at Cape Tribulation. On our return trip we scouted for any better locations considering Port Douglas as an alternative choice as the centre line of the shadow was some where south of this bustling tourist town. Not wanting to be forced to find parking at shared beaches, we revisited the place we had selected on the way up. Ellis Beach is 7 kilomtres north of Trinity Beach and Yorkey’s Knob and a few kilometres north of Palm Cove. This long expanse of coastal beach provided numerous vantage points with plenty of space for the potential hundreds of visitors that were do the same as we were. Many people were already setting up camps along the road, claiming their position as the afternoon went on. After returning to our hotel and balcony, the cloud was still hanging over the east so our minds were set to leave early the next morning and head north.

At 4 am on Wednesday 14th November 2012, we prepared for our journey; having breakfast, gathering tripods and cameras, then packing our hire car we left for the north coast. Arriving at Ellis Beach around 5 am, there were a large crowd already gathered on the beach. We picked  our spot before the sun was above the horizon and set up the cameras. To our dismay there was a thick band of cloud settled above the ocean. Next to us were a couple of Frenchmen along side a family of Ukrainians now living in Melbourne. Brent, a local plaster sat beside us with his cross German Shepard and Stafford-shire  Terrier wondering what the fuss was all about.

The sky began to lighten revealing a bank of low cloud along the ocean horizon. We estimated the point where the sun would rise a little east off the point as the beach faced a more northerly direction. The glow in the horizon surprised us a little to find the rising sun closer to the point than we expected. Nevertheless we still had a perfect view of the sunrise as it broached the horizon like a golden fire spreading across the eastern sky. A scattering of cloud provided a beautiful contrast with the only exception that these cloud were moving into crowd out our sun. At this point we had some concern that the cloud cover was increasing in magnitude inhibiting any vision of the first contact of the sun and moon at 5:44 am. We would miss the beginning of the eclipse process where the moon slowly passes in front of the sun blocking its face and creating a diminishing crescent shape in its passing. This was not such an  important issue as there was forty minutes left until second contact begins. A few mobile phone calls to our colleges at Trinity Beach confirmed that they were experiencing the same cloud cover. With twenty minutes to go the sky was patchy with cloud and there was a chance that the sun would not reveal itself in time. To the north towards Port Douglas, the sky appeared to be clearer but the percentage of cloud was 50% as was the sky east of our beach. There was no point changing locations at this late stage and we sat tight waiting with baited breath as the clock countered down towards the predetermined moment.

Within a minute of the totality, the clouds opened up to reveal the final stage of the first event. A crescent shaped sun appeared through a window in the cloud. the excitement along the beach could be heard as a synchronized sigh of relief was released and anxiety levels percolated  into a feeling of joyful resound. The encroaching shadow was darkening the early morning sun creating an iridescent purple glow to the sky. The temperature dropped a few degrees and the atmosphere retained an eeriness reminiscent of medieval tales of witchcraft and sorcery.  The cloud parted ways within a minute of the moon’s enclosure of the suns surface as the sky darken into twilight making it difficult to read the settings on my camera. Alas I had forgotten to bring a red light torch so I was forced to make guess work of my desired settings. At this point I was taking photographs with my Canon D40 camera via a 2x extender and a Canon 100 to 400mm EF zoom 77mm lens giving me a 800mm telephoto view of the sun through a white light filter. Quickly removing the filter seconds before the second contact began there was time to capture the final 30 seconds of teh sun before totality. The cameras aperture struggled to process the shots with the quickly changing light levels.

A voice behind us countered down the moment, 5..4..3..2..1..A cheers went out along the entire beach. The moon engaged the sun by completely covering its face to reveal a blazing corona. The halo of light sparkled and danced around the edge of the moon as people stood in awe of this pnenominia ong the coast.

Cameras clicked and flashes erupted as hundreds of cameras attempted to capture the experience. Birds that normally would have been actively foraging, nestled themselves chirping and calling their mates to roost. For two minutes the shadow remained on the beach holding the focus of its occupants skyward. My view of the eclipse through the eyepiece of my camera enhanced the solar flares and prominences with their rich red coloured projections extending thousands of kilometres beyond the surface of the chromosphere. Not needing any filtered protection to view this event, observers studied the suns corona and its extended solar winds with the naked eye now visible around the edge of the moon.

Two minutes passed quickly as the moon moved away and the sun returned to shine beyond the edge of the luna satellite. The curve of the moon allows a flash of sun beams to sparkle beyond is surface, bending around the edge of its crators creating an effect known as the Diamond Ring. The glowing pinch of light begins to spread across the lunar circumference quickly growing in intensity until it becomes too bright to view with the naked eye. The third stage of the eclipse begins as the moon moves away and the crescent shape of the sun reappears and increases over the next 40 minutes. Brent, our local plasterer is beside himself having experienced what he discrbes as a biblical event that for many will be the first and only time they will see it in their life. He was so pleased he had decided to come out to witness this before work,  stopping on what would normally be a quiet and secluded beach scape on the side of the highway.

Making a phone call to our friends at Trinity Beach to share the experience, we discovered that they had not seen any of the totality due to the persistent cloud cover. It was almost impossible to imagine that seven kilometres south, the cloud could be so different to where we had been positioned. Within a few minutes a car pulled up and an American tourist from Arizona stepped out to see how our viewing had worked out. He explained that he had passed out position twenty minutes earlier and decided to travel a few kilometres north where he thought the cloud was thinner. They had missed the beginning of the first stage as we had but also missed part of the second stage as the cloud cleared for them just after the totality began. As the crowd dispersed we logged our observations on Facebook and emailed members at home before  we packed our cameras and tripods away. We drove north to Port Douglas in search of a shop for morning tea and spoke to a couple from the Netherlands who had rendezvoused on the northern end of Port Douglas Beach. Apparently the cloud cover there was almost as bad as Trinity Beach only seeing the last half of totality. Another passer by said he was at the southern end of the beach and had 100% advisability of the event. No matter how much research and good preparation you may do before hand, there is always a risk of failure when choosing a place to observe an eclipse. Of all the places we had available to chose, we were just lucky to pick a spot that provided the clear skies at the right time.

This event only occurs because the size of the moon is exactly the same apparent size of the sun. Such a coincidental ratio of star and satellite possibly never occurs anywhere else in the universe. We consider ourselves fortnate and lucky to be have witnessed this event for the third time and hope it won’t be out last.

by

2012 Solar Eclipse Cairns

Categories: Education, Members, Uncategorized, Tags: , , , , , , , , , , , ,

Solar Eclipse: Northern Queensland

14th November 2012

 

On 14th November 2012, Australia will again experience the shadow of the moon as it passes between the Sun and the Earth. This event (second contact) will occur at 20:38UT on November 13th which translates to 6:38 am Australian Eastern Standard Time on 14th November due to the difference in the time zones.

The first point of contact for the shadow will be in the Northern Territory on the north east boarder of Kakadu National Park near Ubirr Rock. The path of the shadow will continue east across Arnhem Land, crossing the Gulf of Carpentaria then onto the Cape York peninsula near Wallaby Island. From here the shadow will progress south east crossing the eastern coast of Queensland 30 km north of Cairns.

Cairns and Port Douglas will provide some of the best viewing areas as they are populated tourist destinations providing ample accommodation and services. At the time of totality, the sun will have risen 14° above the horizon when it will last for two minutes.

As sunrise on the day will be approximately 5:35am, there is an hour available to find the best location for your observation point. there is the option to drive up or down the coast to find the best location north of Port Douglas, where their are open fields and places to stop with many other eclipse chasers. This require a bit of planning the day before as an early start in the dark will make it difficult to see what the cloud cover looks like. My suggestion is to find a comfortable spot on the balcony of your Resort room with a hot breakfast delivered to your room. All-in-all, coast observers might be better advised to sit and take whatever nature offers, as no matter what decision you make it will be just as good as any other on the day.

A total solar eclipse forms a rare opportunity to observe the corona (the outer layer of the Sun’s atmosphere). Normally this is not visible because the photosphere is much brighter than the corona. According to the point reached in the solar cycle, the corona may appear small and symmetric, or large and fuzzy. It is very hard to predict this prior to totality.

  

 

Phenomena associated with eclipses include shadow bands (also known as flying shadows), which are similar to shadows on the bottom of a swimming pool. They only occur just prior to and after totality, when a narrow solar crescent acts as an anisotropic light source

When the shrinking visible part of the photosphere becomes very small, Baily’s beads will occur. These are caused by the sunlight still being able to reach Earth through lunar valleys. Totality then begins with the diamond ring effect, the last bright flash of sunlight.

It is safe to observe the total phase of a solar eclipse directly only when the Sun’s photosphere is completely covered by the Moon, and not before or after totality. During this period the Sun is too dim to be seen through filters. The Sun’s faint corona will be visible, and the chromosphere, solar prominences, and possibly even a solar flare may be seen. At the end of totality, the same effects will occur in reverse order, and on the opposite side of the Moon.

Under normal conditions, the Sun is so bright that it is difficult to stare at it directly. However, during an eclipse, with so much of the Sun covered, it is easier and more tempting to stare at it. In fact however, looking at the Sun during an eclipse is as dangerous as looking at it outside an eclipse, except during the brief period of totality, when the Sun’s disk is completely covered (totality occurs only during a total eclipse and only very briefly; it does not occur during a partial or annular eclipse). Viewing the Sun’s disk through any kind of optical aid (binoculars, a telescope, or even an optical camera viewfinder) is extremely hazardous and can cause irreversible eye damage within a fraction of a second.

Looking directly at the photosphere of the Sun (the bright disk of the Sun itself), even for just a few seconds, can cause permanent damage to the retina of the eye, because of the intense visible and invisible radiation that the photosphere emits. This damage can result in impairment of vision, up to and including blindness. The retina has no sensitivity to pain, and the effects of retinal damage may not appear for hours, so there is no warning that injury is occurring.

Photographing an eclipse is possible with fairly common camera equipment. In order for the disk of the Sun/Moon to be easily visible, a fairly high magnification long focus lens is needed (at least 200 mm for a 35 mm camera), and for the disk to fill most of the frame, a longer lens is needed (over 500 mm). As with viewing the Sun directly, looking at it through the viewfinder of a camera can produce damage to the retina, so care is recommended.

For more detailed information on eclipse photography visit:

http://www.eclipse-chasers.com/Photo.html

http://joe-cali.com/eclipses/PLANNING/TSE%202009p/beginner_eclipse_photo.html