The Southern Cross

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“The Southern Cross”



JULY 2013
Welcome to this month’s newsletter which, we hope, you find informative and enjoyable. We also welcome new members Johan Hugo and John Taylor.
National Science Week The Centre will be running several activates as part of this event, which runs from 27 July – 3 August. Details of this exciting public educational outreach programme can be found below in the Educational Activity section of the newsletter
Reminder of important amendment to payment systems Please note that the existing options of payments to the Centre by cheque and by making direct cash deposits into the Centre’s account have had to be withdrawn with immediate effect. We are disappointed at having to make these changes, but have been forced to do so by the associated charges levied by banks when money is deposited by these routes. The options still available to members are cash payments directly to the Treasurer at meetings, and online payments.

A quartet of celestial objects - Moon, Spica, Saturn and Scorpius Examples

of four celestial features can be seen close to each other in the middle of the

month: a constellation (Scorpius), a star (Spica), a planet (Saturn) and a satellite

(the Moon). The constellation is easy to identify, with the characteristic S shape

resembling the animal for which it is named. The large red star at the ‘heart’

of the scorpion is Antares (Alpha Scorpii), a supergiant 400 times larger than the

Sun and 604 light years (ly) away. Of the two bright objects to the left of Scorpius,

Saturn is the one on the right. Saturn is twice as far away from Earth than Jupiter

is. It takes 29.46 years to orbit the Sun, but a full rotation on its own axis is

completed in only ten hours. Strong binoculars may show a bump on either side of the planet, but a telescope is needed to see its rings and the larger of its many moons. Spica (Alpha Virginis) is by far the brightest star in the second largest constellation, Virgo. A telescope is needed to in order to observe any of its other stars, clusters and galaxies in any detail.


Monthly centre meeting For logistical reasons, the scheduled meeting on 13 June had to be postponed to 20 June. Unfortunately, illness prevented the Centre chairperson, Pierre de Villiers, from giving his presentation on the Hubble telescope. It will be rescheduled for later this year or early 2014.

Instead, attendees watched Part 1 of the three-part BBC series ‘Orbit: Earth’s extraordinary journey’. The presenters looked at a number of natural events which are a direct consequence of Earth’s annual orbit of the Sun, and its daily rotation. These included the seasonal solstices and equinoxes, the formation and pattern of global weather systems and ocean currents, and daily tides. The DVD was very well received, and viewing of the other two parts will be scheduled for the near future.

Cosmology At the meeting on 3 June, eleven people (10 members, plus 1 visitor) participated in consideration of the spatial flow model. Pierre Hugo presented the next two sessions on the topic: Part 3 – ‘The rain frame, free falling inertial systems and spherical symmetry’ and Part 4 – Acceleration fields and gravity’. This was followed by a lively question and discussion session.
Beginner’s astronomy Fifteen people attended the meeting on 1O June (12 members, 3 visitors). They watched DVDs ‘Star clusters, ages and remote distances’ and ‘How stars shine - nature's nuclear reactions’ before learning more about star-gazing.
Astro-photography Four members attended the meeting held on 17 June. They shared the results of the work they had done on image processing, discussing their quality and any difficulties they encountered while undertaking the processing activity. The group then discussed the relevant processing steps and techniques to be used in obtaining a good quality image in preparation for the exercise they will undertake for the next meeting.
Other activities

Educational activity Lynette Geldenhuys reports the following about National Science Week (NSW): “Preparations for the HAC participation in National Science Week from 27 July to 3 August are progressing well. This national event is planned and funded by SAASTA (South African Agency for Science and Technology Advancement), a division of the National Research Foundation (NRF). The aim is to foster interest in science and mathematics in both adults and children, as there is a shortage of these skills in the country.
The HAC has organised 3 public and 7 school events for the week, covering the area from Gansbaai to Kleinmond. The public events will consist of 2 evenings of Sidewalk Astronomy stargazing at Gearings Point, as well as 1 public lecture at the Municipal Auditorium. The public lecture will consist of a screening of the fascinating DVD detailing the trials and tribulations of the Mars Rover, and a very interesting talk by Johan Retief on the formation of waves, highlighting what you can learn about the waves by observation and applying some simple ‘beach’ mathematics. The evening will also include a short introduction to SKA and an opportunity for the public to ask questions.
For the schools, we are focusing mainly on the Grade 7s this year as well as a small component of Grades 10 to 12. The Grade 7s will be entertained with the concepts of day and night and seasons as a result of planetary movement, as well as the same talk on waves and wave formation, including simple practical ‘beach’ mathematics.
Schools will also receive astronomy posters, bookmarks, pocket periodic tables and assorted career guidance information brochures.
In addition, selected grades 10 to 12 learners from Curro and Hermanus High will take part in advanced astronomy observation work during a link-up with the Monet telescope in Austin Texas, very ably guided by Deon Krige.”
We would welcome the assistance of volunteers from the membership during NSW. If you would like to volunteer, or find out what would be involved, please contact Lynette at or on 028 316 2428.
Youth club The June meeting took the form of a very successful star-gazing evening. On the 11th, fifteen club members from Lukhanyo Primary School and their two science teachers joined a number of committee members on Rotary Way. The learners had the opportunity to observe the crescent Moon, Saturn, and several constellations, particularly the Southern Cross and Scorpius, as well as both globular and open clusters. They did this with the naked eye, and through binoculars and telescopes. Club members were fascinated by what they saw and learned, demonstrating knowledge and understanding, and asking many relevant and pertinent questions.

Monthly centre meeting The presenter at the meeting on 11 July will be Centre member, Johan Retief. His topic is ‘Observing deep sky objects for rank amateurs’. Johan has been the most prolific presenter since the formation of the Centre, and this presentation will, no doubt, prove to be as interesting and informative, and, at times, amusing as his others have been.

Weather permitting, there will be an opportunity for stargazing from the SANSA car park. An entrance fee of R20 will be charged per person for non-members and R10 for children and students.
Interest group meetings

The Cosmology group meets meeting on the first Monday of the month at 7 pm at SANSA. This month’s meeting will take place on 1 July. Pierre Hugo will continue his presentations on the spatial flow model. The topics for this month are: Part 5 – ‘Fields, particles and inertia’ and Part 6 – ‘Background independent space, vacuum energy and inertia’.

An entrance fee of R20 will be charged per person for non-members and R10 for children and students. For further information on these meetings, or any of the group’s activities, please contact Pierre Hugo at
Beginner’s astronomy Meetings take place monthly on the second Monday of the month at 7 pm at SANSA. The date for this month’s meeting is 8 July. The topics will be ‘Using the Sky Guide for Southern Africa to plan your star gazing’ and ‘Star-gazing at the southern hemisphere winter sky.’ Weather permitting, this will be followed by practical observation of the southern skies with binoculars. NB If you have one, please bring your copy of the 2013 Sky Guide with you to the meeting.
An entrance fee of R20 will be charged per person for non-members and R10 for children and students. Please contact Pierre de Villiers at for further details.
Astro-photography This group meets on the third Monday of each month. The next meeting will take place on 15 July. Members will continue image processing work using PhotoShop.
To find out more about the group’s activities and the venue for particular meetings, please contact Deon Krige at

Sidewalk astronomy Details of the next events, which will form part of National Science Week, will be circulated in due course.
MONET project The first practical session with the telescope is scheduled to take place on 2 August, as part of the activities planned for learners in National Science Week. This will give the participating learners from Hermanus High and Curro schools the opportunity to apply the theory they have learned during the introductory sessions held earlier in the year.
For further information on the project, please contact Deon Krige at

These take place at 7 pm at SANSA on the following Thursdays:

11 July ‘Observing deep sky objects for rank amateurs’. Presenter:

Johan Retief, Centre member

8 August ‘Einstein – the man (and a little bit about his work)’ by Lisa

Labuschagne, ASSA, CT

12 September Topic: TBA Presenter: Lisa Crause, SAAO, CT

10 October ‘The story of the Herschels (Part 2)’ by John Saunders, Centre

committee member

7 November ‘Of clocks and comets, coronas and quasars: the lives and times

of the Astronomers Royal’ by Jenny Morris, committee member

6 December Christmas party


We continue to await publication of the Fernkloof Management Plan. This will be followed by a thirty day period for receipt of public comments and objections and a period of time to respond to each individual objection before the Plan, which includes the application to construct the AECO, is tabled for consideration by the Council of Overstrand Municipality.

Meanwhile, the ‘Friends of the Observatory’ campaign continues in order to enable payment of outstanding costs. We are very grateful to members who have already contributed to this, and hope that the generosity of the Centre’s membership continues. Both single donations and small, regular monthly donations, of any amount, are welcome.
Contributions can take the form of cash (paid at meetings), or online transfer, The ABSA bank details are as follows:

Account name – Hermanus Astronomy Centre

Account number – 92 3016 3786

Branch code – 632005.

If you make an online donation, please include the word ‘pledge’, and your name, unless you wish to remain anonymous.

Hubble spots galaxies in close encounter 20 June: Just below the centre of the image below is the blue, twisted form of galaxy NGC 2936, one of the two interacting galaxies that form Arp 142 in the constellation of Hydra. Nicknamed ‘the Penguin’ or ‘the Porpoise’ by amateur astronomers, NGC 2936 used to be a standard spiral galaxy before being torn apart by the gravity of its cosmic companion.
The remnants of its spiral structure can still be seen — the former galactic bulge now forms the "eye" of the penguin, around which it is still possible to see where the galaxy's pinwheeling arms once were. These disrupted arms now shape the cosmic bird's "body" as bright streaks of blue and red across the image. These streaks arch down towards NGC 2936's nearby companion, the elliptical galaxy NGC 2937, visible here as a bright white oval. The pair shows an uncanny resemblance to a penguin safeguarding its egg.
The effects of gravitational interaction between galaxies can be devastating. The Arp 142 pair is close enough together to interact violently, exchanging matter and causing havoc.
In the upper part of the image are two bright stars, both of which lie in the foreground of the Arp 142 pair. One of these is surrounded by a trail of sparkling blue material, which is actually another galaxy. This galaxy is thought to be too far away to play a role in the interaction — the same is true of the galaxies peppered around the body of NGC 2936. In the background are the blue and red elongated shapes of many other galaxies, which lie at vast distances from us, but which can all be seen by the sharp eye of Hubble.
The NASA/ESA Hubble Space Telescope has produced this vivid image of a pair of interacting galaxies known as Arp 142. When two galaxies stray too close to each other they begin to interact, causing spectacular changes in both objects. In some cases the two can merge — but in others, they are ripped apart.

his pair of galaxies is named after the American astronomer Halton Arp, the creator of the Atlas of Peculiar Galaxies, a catalogue of weirdly-shaped galaxies that was originally published in 1966. Arp compiled the catalogue in a bid to understand how galaxies evolved and changed shape over time, something he felt to be poorly understood. He chose his targets based on their strange appearances, but astronomers later realised that many of the objects in Arp's catalogue were, in fact, interacting and merging galaxies.
This image is a combination of visible and infrared light, created from data gathered by the NASA/ESA Hubble Space Telescope Wide Field Planetary Camera 3 (WFC3).
IRIS Science Overview

At the end of June 2013, NASA will launch its newest mission to watch the Sun: the Interface Region Imaging Spectrograph, or IRIS. IRIS will show the lowest levels of the sun’s atmosphere, the interface region, in more detail than has even been observed before. This will help scientists understand how the energy dancing through this area helps power the Sun’s million-degree upper atmosphere, the corona, as well as how this energy powers the solar wind constantly streaming off the sun to fill the entire solar system.

A giant postcard from Mars This full-circle view combined nearly 900 images taken by NASA's Curiosity Mars rover, generating a panorama with 1.3 billion pixels in the full-resolution version. The view is centred toward the south, with north at both ends. It shows Curiosity at the ‘Rocknest’ site where the rover scooped up samples of windblown dust and sand. Curiosity used three cameras to take the component images on several different days between 5 October and 16 November 2012.

Billion-Pixel View From Curiosity at Rocknest, Raw Colour

This version of the panorama retains ‘raw’ colour, as seen by the camera on Mars under Mars lighting conditions. A white-balanced version is available at The view shows illumination effects from variations in the time of day for pieces of the mosaic. It also shows variations in the clarity of the atmosphere due to variable dustiness during the month while the images were acquired.

Credit: NASA/JPL-Caltech/MSSS
Bubbles in space This infrared image shows a striking example of what is called a hierarchical bubble structure, in which one giant bubble, carved into the dust of space by massive stars, has triggered the formation of smaller bubbles. The large bubble takes up the central region of the picture while the two spawned bubbles, which can be seen in yellow, are located within its rim.

NASA's Spitzer Space Telescope took this image in infrared light. The multiple bubble family was found by volunteers participating in the Milky Way Project (see This citizen science project, a part of the Zooniverse group, allows anybody with a computer and an Internet connection to help astronomers sift through Spitzer images in search of bubbles blown into the fabric of our Milky Way galaxy.

The bubbles are formed by radiation and winds from massive stars, which carve out holes within surrounding dust clouds. As the material is swept away, it is thought to sometimes trigger the formation of new massive stars, which in turn, blow their own bubbles.
The images in the Milky Way project are from Spitzer's Galactic Legacy Infrared Mid-Plane Survey Extraordinaire, or Glimpse, project, which is mapping the plane of our galaxy from all directions. As of June 2013, views of 130 degrees of the sky have been released. The full 360-degree view, which includes the outer reaches of our galaxy located away from its centre, is expected soon.
A Strawberry Supermoon? The weekend of the Southern Winter Solstice coincided with the “Strawberry Moon”, the first full Moon of the northern summer. This one was extra special because the Moon was at its closest approach to Earth (at perigee).
f course, there’s nothing super about it. The Moon is at perigee once during every 29-day lunar orbit. But, the effect is most noticeable when it coincides with full Moon and the term ‘super moon’ has caught on to such an event. This June it technically occurred at 11:32 Universal Time on Sunday, 23 June. The effect of this closeness on brightness is most noticeable on the day before and afterwards.
A “supermoon” is about 15% brighter than an average full Moon

t perigee, the full Moon is about 14% larger in diameter and 30% brighter than a full Moon at apogee, when it’s furthest away. Compared to its average distance, it’s 7% larger in diameter and 15% brighter. If you’re an experienced Moon watcher, you will have noticed the unusual brightness. And if you’re not, it’s still an impressive sight.
An asteroid record 25 June: The count of known asteroids and comets that can come close to Earth continues to climb. The 10,000th near-Earth object, asteroid 2013 MZ5, was detected on 18 June 2013 by the Pan-STARRS-1 telescope.
Source: NASA Science News

Ancient astronomy Part 10: Inca and Aztec astronomy: where calendars were crucial for Andean agriculture and Central American religion

Temple of the sun, Machu Picchu Aztec calendar stone

Inca astronomy

The Inca empire, the largest in the New World before the European invasions, was a powerful social structure centred on the city of Cuzco in the Peruvian Andes, although it encompassed an area of over 375,000 square miles. Its impressive legacy, including the structures at Machu Picchu tends to hide the fact that, in fact, it only lasted around one century until the Spanish conquest in the 16th century CE. Astronomy was a very important part of the culture, probably because of the importance of agriculture to the empire. In addition to its practical uses, astronomy was also the source of a number of powerful gods who, by controlling the weather, health, fertility and time itself, were believed to hold the fate of the empire in their hands.

Like ancient Egypt and India, Inca astronomy was horizon-focussed with the most important events involving certain risings and settings of the Sun, Moon and stars. The rising of Pleides signalled the start of the Inca year. The Sun was central to Inca astronomy and the basis of the Inca calendar. They built carefully positioned sets of pillars on hills overlooking Cuzco and when the Sun rose or set between certain ones at different times of the year, it was time to start planting crops at particular altitudes. Venus was regarded as a servant of the Sun, always nearby and ordered either to go ahead in the evening, or follow in the morning. The Sun was also the focus of their observatories, which captured the first and last rays through specifically designed and placed windows. The main observatory was the ‘golden enclosure’. Covered in gold, it also contained a gold sun disc which faced the rising Sun. This was one of the sites whose gold was pillaged by the Spaniards.
At Machu Picchu there is a Temple of the Sun located in the most sacred and private area of the city. Unlike the pillars overlooking Cuzco, this was small, and only open to a small number of astronomers. The shadow cast on a central rock by a plumbline marked the path of the Sun throughout the day and the year (a shadow clock), but was particularly important in marking the winter solstice, the start of the coming summer and another agricultural year.
Aztec astronomy

Like other Meso-American peoples, the Aztecs tracked the movements of the celestial bodies, work done mostly by nobles and priests. Some of the religious rituals deemed necessary to keep the Sun on its course and the Earth bountiful involved blood sacrifices. As the ancient Egyptians did independently millennia earlier, the Aztecs orientated plans for cities and important buildings along lines determined by the tracks of the Sun, Moon, planets and stars. Equinoctial lines were particularly important. In addition to regular celestial cycles, the Aztecs also observed eclipses and comets, seeing them as sources of omens. For example, the comet seen by Montezuma prior to the Spanish invasion was interpreted as a forewarning of impending crisis.

Unlike the Incas, Aztec astronomy was mostly undertaken for religious and ritual purposes, although it is likely that their 365-day solar calendar was also used for agricultural purposes. The Aztec calendar was a complex one, based on the earlier Mayan calendar. A 260-day ritual calendar counted days for religious purposes, while the 365-day calendar counted the years. The Aztec year consisted of 18 months of 20 days each, each month having a specific name. An additional 5 sacrificial days made the total of 365. The start of each of these aligned on a 52 year cycle, effectively an Aztec century, the change from one to another a time of important religious festivals.
All these cycles are included in the large, round stone Aztec Sun Calendar. Weighing 24 tones, it was 12 feet in diameter and 3 feet deep. At the centre was the face of the Aztec sun god. This was then surrounded by circles containing information including months, days etc. Each day of the 20-day month was represented by an object from nature or from everyday life eg. snake, wind, house. In a system reminiscent of the Mayans, the calendar told them that they were living in the fifth and final world. Taking 50 years to construct (from 1427 – 1479), the calendar was initially placed on top of the temple in Tenochtitlan, the Aztec capital. After the Spanish invasion, the calendar was ‘lost’ for 250 years, until it was found in 1790 by workers repairing the cathedral in Mexico City.
Sources,, www.spaceodyssey.dmns,org,,,
For more information on the Hermanus Astronomy Centre and its activities, visit our website at

Pierre de Villiers (Chairperson and AECO) 028 313 0109

Laura Norris (Treasurer) 028 316 4453

Peter Harvey (Secretary, including membership) 028 316 3486

Jenny Morris (Vice-chairperson and newsletter editor) 071 350 5560

Derek Duckitt (Website editor) 082 414 4024

Lynette Geldenhuys (Education co-ordinator) 028 316 2428

Deon Krige (MONET project and astrophotography) 028 314 1045

John Saunders (Youth club co-ordinator) 028 314 0543

Hugo Slabbert (Events co-ordinator) 028 312 4118

Non-committee members with roles:

Pierre Hugo (Cosmology interest group co-ordinator) 028 312 1639

Steve Kleyn (Technical advisor & newsletter astronomy news)

Johan Retief (Monthly sky maps) 028 315 1132

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