Public astronomy outing in Jack Muller / Danie Uys park in Bellville (Boston).
Ricardo (Ricky) Adams and Zenobia (Zee) Rinquest approached Auke, Lynnette and I to join them for a public astronomy outreach in celebration of Global Astronomy Month 2015 which youcan read more about here. They had a venue all planned and were looking for fellow astronomy enthusiasts to enjoy the outing with them. Ricky was associated with the Iziko Planetarium for a long time and when he spoke to Theo Ferreira the MMWC at the Planetarium, Theo was kind enough to recommend us and also to arrange for support in the form of the Iziko bus with the three museum stalwarts, Temba Matomele, Sthembele Harmans and Luzuko Dalasile. You can read more about the Iziko outreach program here.
Ricky and Zee’s outfit, Kingdom Skies, boasts a portable planetarium and they had plans to put that up as part of the show. Read more about them here. Eventually they were unable to do that due to various logistical problems but mainly because of a whole lot of red tape. As it turned out their planetarium would have been a tremendous asset on the specific evening because the weather gods were there usual fickle selves and we had cloudy conditions on the evening in question.
Auke had a prior commitment for that weekend as he and Hans van der Merwe were off to Van Rhynsdorp with the rest of the crew to carry out one of their high altitude balloon launches. The base station was in Van Rhynsdorp and the launch site was at the top of Van Rhyn’s Pass. He was due back on Saturday morning but balloon launches, like the path of true love, apparently do not always run smoothly. This one was no exception and Auke did not make it back on time. There is a If you click here you will be taken to a photograph of the setup.
Lynnette and I were on site by 16:00, as was the Iziko bus with Sthembele and Luzuko. Ricky and Zee arrived a little later as they had to make a detour to pick up Temba, who was going to give a talk on Indigenous Southern African Astronomy later in the evening. Zee’s volunteers had disappeared but were later found waiting outside the Bellville Public Library.
Once we started setting up everything went quite quickly, although the amount of cloud overhead did not bode well for stargazing later in the evening. By 17:30 we decided to capitalize on the fact that the Moon was visible through gaps in the clouds and Zukile and I started showing it to the first guests. After the sun set we managed to show people Jupiter too before the clouds realized what we were up to and started closing up the gaps.
Temba gave his talk and Ricky was fortunate to have some stars when he gave a brief what’s-up tonight. I did a short talk on light pollution and emphasized the fact that everyone could help by ensuring that lights around our homes were astronomy friendly. By 20:30 it was clear that the clouds were definitely winning and we all started packing up.
All in all it was a very pleasant evening and I think the venue has a good deal of potential for events like this in the future. Thanks Ricky and Zee for inviting us along and it was a pleasant experience to work with you guys and the team from Iziko.
A new wind farm has been taking shape at Gouda in the Drakenstein Municipality of the Western Cape.
When Lynnette and I recently went to Porterville for the stargazing event at the Porterville Golfclub, organized by Nathalie Wagenstroom from the Porterville Tourism Office, I hadn’t been out that way for quite some time. I was therefore surprised to find that a new wind farm had sprouted up to the right of the R44 just past where it crosses the railway line.
This wind farm will consist of forty-six 100 m towers each carrying a 3 MW Acciona wind-power turbine so that the site can produce 138 MW at full capacity. The construction started in 2013 and was scheduled for completion in 2014 with the power being delivered to a 132 kV distribution network at the Windmeul substation near Wellington. Go here to read more about the project in the August edition of Engineering News. You will find a comprehensive overviewof the project as summarized in the August 2013 NERSA public hearings. There is more information here on the webpage of Energy4Africa. Driving past there it was clear that they are way behind schedule.
The Gouda Wind Facility is the first wind farm in South Africa to use concrete towers. Steel towers are imported while concrete towers can be manufactured locally. Another advantage is that one can build taller towers, up to 120 m, at a reduced energy cost. The wind farm at Hopefield consists of thirty-seven, 95 m steel towers each carrying a 1.78 MW turbine from the Danish firm Vestas. The installation will produce 66 MW at full capacity. Go here to read about the installation in the May 2014 edition of Engineering News.
The Gouda installation was erected by Acciona Energy and Aveng while Sarens supplied the equipment to transport and lift the various sections of the towers as well as the turbine blades and the turbines. At full capacity Gouda will supply enough power for 146 000 low income homes or 60 000 medium income homes.
Each blade of the three-blade turbine is 50 m long and the pitch of the blades is increased as wind speed drops to increase the torque and maintain the rotation speed. If the wind speed increases the pitch will be decreased to reduce the torque. At wind speeds of around 20 m/s at the hub height (that is around 70 km/h) the turbines are shut down. In rural areas the turbine blades are required to generate no more than 35 decibels of sound which is classified as less noise than a normal conversation.
When one sees these turbine blades rotating they always look as if they are in slow motion. A bit of mathematics reveals that if the rotor is turning at 10 revolutions per minute the tips of those 50 m long blades are travelling at over 180 km/h. Low flying birds cannot judge the speed of those rotor tips correctly and, because the rotors taper, the tips are far less visible than the sections closer to the hub, so they fly into them, with fatal results. This is especially the case for large, slow birds like geese, pelicans, cranes and storks. Raptors tend to be watching for prey on the ground so they also often fall foul of the blades. From an environmental perspective, it is important that wind farms should not be built on the migration routes of these birds, or in areas where they congregate to feed or breed.
13 April 2015 – First South African Comet Discovery in 35 Years
In the early hours of the 7th April, an un-manned robotic telescope, MASTER-SAAO, situated near Sutherland in the Karoo, discovered a new comet. This is the first comet to be discovered in South Africa since 1978.The Russian – South African run telescope has been scanning the southern skies since it began operating in late December 2014, looking for “transients” – new objects which appear in the sky for the first time. Since then, over 60 newobjects have been discovered, most of them being erupting or exploding stars. However, the MASTER-SAAO telescope has just discovered its first comet. Please go here to read all about the discovery and see pictures on the SAAO website