Welcome to this month’s newsletter. We hope you find it interesting and informative.
Many thanks to those who have responded to our ‘Friends of the Observatory’ pledge campaign. We continue to welcome any size donation, small or large. Contributions can take the form of cash, cheque or online transfer, either as one payment, or on a monthly payment basis.
The ABSA bank details are as follows:
Account name – Hermanus Astronomy Centre
Account number – 9230163786
Branch code – 632005.
If you make an online donation, please include the word ‘pledge’ and your name, unless you wish to remain anonymous.
For further information, please contact John Saunders on 028 314 0543 or at email@example.com
Visit to Carnarvon
A few places are still available for the weekend of 11–13 November. Please contact John Saunders for further information.
The party on Friday 9 December will take place at Molteno’s restaurant in Onrus. Details will be circulated soon.
The large constellation of Taurus can be found to the west of upside down Orion. It contains two easily identified open clusters. The inverted V of the Hyades includes reddish-coloured Aldebaran (Alpha Tuari). Further away from Orion, is the Pleides, popularly known as the Seven Sisters. Six of these seven stars are easily visible to the naked eye, but the cluster looks even more dramatic when viewed with binoculars, when a large number of other stars can also be seen.
LAST MONTH’S ACTIVITIES
Monthly centre meeting On 6 October
Dr Deborah Shepherd, Commissioning Manager for the South African Karoo Array Telescope (MeerKAT), gave a fascinating presentation on radio astronomy and the future developments planned for the radio telescope facility near Carnarvon. The longer wavelengths of radio waves make it easier for this radiation to escape dark gas clouds, providing information on ionized gases not available at visible wavelengths. Using stunning illustrations, Dr Shepherd showed how radio astronomy is able to identify features arising from galaxy collisions and stellar explosions which extend huge distances beyond those visible to optical instruments.
The more antennae used, the richer the data received, and the resulting image. This is the motivation behind the current development of very large radio telescope arrays. Using the ALMA array, its 64 12-metre movable dishes currently under construction in Chile, as a working example, Dr Shepherd outlined the planned expansion of the existing KAT-t facility in the Karoo. MeerKAT has been approved. It will also have 64 12-metre antennae, but they will receive longer wavelength data than ALMA does. It is hoped that MeerKAT will form the germ of the proposed square kilometer array (SKA), so-called because the total surface area of all the antennae would be approximately that area. South Africa is competing with Australia for the SKA, which will be the world’s largest radio telescope, with 1000s of antennae, based in different countries. The South African SKA will have antennae across Africa. A hugely expensive international project, the SKA will be able to see back in time to before stars were formed, with the possibility of identifying dark energy, gravitational waves, gravity close to black holes, cosmic magnetism, and life elsewhere in the universe.
On 3 October, 19 people watched the final part of the 3-part DVD ‘Atom’. The 16 members who attended the 17 October meeting re-viewed Part 26 of the ‘Cosmology’ DVD series ‘Putting it together – the concordance model’. This was followed by general discussion on content covered in the lecture.
Beginners astronomyTen people attended the PowerPoint presentation on an introduction to astronomy held on 10 October.
While members of the public were able to view the night sky on 7 October, poor weather prevented viewing on 8 October.
Presentation to hospice
On 25 October, John Saunders gave the ‘Introduction to astronomy’ PowerPoint presentation to approximately 20 people who were attending a hospice gathering.
Southern star party
A few members attended a very successful weekend event held on 22-23 October near Bonnievale. Talks on various astronomical topics were given during the day, and the star-gazing on each night was led by experienced amateur astronomers, including past HAC presenters Auke Slotegraaf and Ed Foster.
THIS MONTH’S ACTIVITIES
Monthly centre meeting
On 3 November, amateur astronomer and psychohistorian, Auke Slotegraaf, will be giving a presentation on the life and work of Sir John Herschel. Auke’s knowledgeable and entertaining style has proved popular with members at previous talks for the Centre, and promises to be so once again.
Son of William Herschel, John added substantially to his father’s discoveries, including during time spent in Cape Town, collecting their combined discoveries into a catalogue which formed the basis of the New General Catalogue (NGC), whose numbers are still in use. He also made other contributions to astronomy, including early measurement of the solar constant and pioneering astro-photography.
As usual, tea and coffee will be available after the presentation and, weather permitting, an opportunity for star-gazing. Non-members are welcome for a fee of R20 (R10 for students and children).
Interest group meetings
The Cosmology group meets on the first and third Monday of every month at 7 pm at SANSA. At each meeting, a ‘Cosmology’ DVD lecture will be re-screened, followed by discussion led by a group member. Lectures for consideration in November are: 7 November: ‘From child to maturity – galaxy evolution’, and 21 November: ‘Overall cosmic properties’
Visitors who attend for one evening are welcome for free, but will need to join the Centre if they wish to attend further meetings. For further information on these meetings, or any of the group’s activities, please contact Pierre Hugo at firstname.lastname@example.org
Beginner’s astronomy The next meeting will take place early in 2012. The 2012 schedule will be circulated in due course.
2011 MONTHLY CENTRE MEETING SCHEDULE
These will take place at 7 pm at SANSA (formerly HMO).
3 November ‘Sir John Herschel’ by Auke Slotegraaf, psychohistorian and amateur astronomer
9 December Christmas party
2012 MONTHLY MEETING DATES The proposed dates for next year are: 26 January, 23 February, 22 March, 26 April, 24 May, 21 June, 19 July, 23 August, 20 September, 18 October, 15 November, and 14 December. Confirmation and presentation details will follow.
EDUCATION CENTRE AND OBSERVATORY
On 28 October, John & Irene Saunders and Pierre de Villiers had a meeting with Duncan Heard, chair of Fernkloof Advisory Board (FAB), and Liesl Bezuidenhout and Grant Forbes, Overstrand Municipality Fernkloof Management staff. The HAC representatives were able to clarify queries and correct inaccuracies. A presentation in the near future on the project to members of FAB was agreed.
Now that the 31 October closing date for public objections to the lease application has passed, the application and any objections will be considered by the Municipality.
ASTRONOMY NEWS FROM STEVE KLEYN
600 mysteries in the night sky NASA’s Fermi team recently released the second catalogue of gamma-ray sources detected by their satellite’s Large Area Telescope (LAT). Of the 1873 sources found, nearly 600 are mysteries. No one knows what they are. “Fermi sees gamma rays coming from directions in the sky where there are no obvious objects likely to produce gamma rays,” says David Thompson, Fermi Deputy Project Scientist, Goddard Space Flight Center.
Gamma rays are by their very nature heralds of great energy and violence. They are a super-energetic form of light produced by sources such as black holes and massive exploding stars. Gamma-rays are so energetic that ordinary lenses and mirrors do not work. As a result, gamma-ray telescopes cannot always get a sharp enough focus to determine exactly where the sources are.
For two thirds of the new catalogue’s sources, the Fermi scientists can, with at least reasonable certainty, locate a known gamma ray-producing object, such as a pulsar or blazar, in the vicinity the gamma-rays are coming from. However, the remaining third – the “mystery sources”- have the researchers stumped, at least for now. And they are the most tantalizing. Nearly 600 sources in the latest Fermi catalogue are unidentified. “Some of the mystery sources could be clouds of dark matter, something that’s never been seen before,” speculates Thompson.
About 85% of the gravitational mass of the universe is dark matter. The stuff we see makes up the rest. Dark matter is something that pulls on things with the force of its gravity but cannot be detected in any other way. It doesn’t shine – doesn’t emit or scatter light – hence the adjective “dark.” Astronomers cannot detect dark matter directly using optical or radio telescopes. However, dark matter just may shine in gamma rays.
“We’ve been using Fermi to search for dark matter for a long time,” says the principal investigator for the Large Area Telescope, Peter Michelson of Stanford University. Some researchers believe that when two dark matter antiparticles bump into each other, they will annihilate, producing gamma rays. Concentrated clouds of dark matter could form a gamma ray source at specific wavelengths detectable by Fermi. “If we see a bump in the gamma-ray spectrum — a narrow spectral line at high energies corresponding to the energy of the annihilating particles – we could be the first to ‘apprehend’ dark matter,” says Michelson.
The team plans to continue observing the mystery sources. Fermi scans the entire sky ever three hours, and this ongoing sequence of observations “piles up” gamma rays for the researchers to analyze. So far, too few gamma rays have been collected from the mystery sources to form definite conclusions.
Colliding galaxy clusters are another, less-dark possible explanation for the mystery sources. According to Michelson and Thompson, clashes of such magnitude would generate super large scale shock waves that would accelerate particles. Others of the sources, they say, might be some brand new phenomenon, perhaps something involving galactic black holes. When all is said and done, many of the mystery sources could prove to be familiar. “[They] will probably turn out to be members of known source classes – things we know but haven’t recognized yet, like undiscovered pulsars, binary systems, and supernova remnants,” says Michelson. “Of course we’re hoping for something really exotic like dark matter, but we have to look first at all the other options,” says Thompson. “Fermi is an ongoing mission. We’ll continue to search for answers to these puzzles and perhaps turn up even more surprises.”
Author: Dauna Coulter | Editor: Dr. Tony Phillips | Credit: Science@NASA
New mystery on Mars’s forgotten plains One of the supposedly best understood and least interesting landscapes on Mars is hiding something that could rewrite the planet’s history. Or not. In fact, about all that is certain is that decades of assumptions regarding the wide, flat Hesperia Planum are not holding up very well under renewed scrutiny with higher-resolution, more recent spacecraft data.
“Most scientists don’t want to work on the flat things,” noted geologist Tracy Gregg of The University at Buffalo, State University of New York. So, after early Mars scientists decided Hesperia Planum looked like a lava-filled plain, no one really revisited the matter and the place was used to exemplify something rather important: the base of a major transitional period in the geologic time scale of Mars. The period is aptly called the Hesperian and it is thought to have run from 3.7 to 3.1 billion years ago.
But when Gregg and her student Carolyn Roberts started looking at this classic Martian lava plain with modern data sets, they ran into trouble. “There’s a volcano in Hesperia Planum that not many people pay attention to because it’s very small,” Gregg said. “As I started looking closer at the broader region — I couldn’t find any other volcanic vents, any flows. I just kept looking for evidence of lava flows. It’s kind of frustrating. There is nothing like that in the Hesperia Planum. A likely cause of this trouble is the thick dust that blankets Hesperia Planum,” she said. “It covers everywhere like a snowfall.”
So she turned her attention to what could be discerned on Hesperia Planum: about a dozen narrow, sinuous channels, called rilles, just a few hundred meters wide and up to hundreds of kilometers long. These rilles have no obvious sources or destinations and it is not at all clear they are volcanic. “The question I have is what made the channels,” said Gregg. Was it water, lava, or something else? “There are some lavas that can be really, really runny. And both are liquids that run downhill.” So either is a possibility.
To begin to sort the matter out, Gregg and Roberts are now looking for help on the Moon. Their preliminary findings were presented at the meeting of The Geological Society of America in Minneapolis on 12 October. “On the Moon we see these same kinds of features and we know that water couldn’t have formed them there,” Gregg said. So they are in the process of comparing channels on the Moon and Mars, using similar data sets from different spacecraft, to see if that sheds any light on the matter. She hopes to find evidence that will rule out water or lava on Hesperia Planum.
“Everybody assumed these were huge lava flows,” said Gregg. “But if it turns out to be a lake deposit, it’s a very different picture of what Mars was doing at that time.” It would also make Hesperia Planum a good place to look for life, because water plus volcanic heat and minerals is widely believed to be a winning combination for getting life started. “The ‘volcanic’ part is an interpretation that’s beginning to fall apart,” said Gregg. “What is holding up is that the Hesperian marks a transition between the Noachian (a time of liquid water on the surface and the formation of lots of impact craters) and the Amazonian (a drier, colder Mars).”
She has found that other scientists are interested in her work because of its possible implications on the Mars geological time scale. Gregg is not worried that Mars history will need to be rewritten, but she does suspect that Hesperia Planum is a lot more complicated than people has long thought.
Source: Geological Society of America press release
DID YOU KNOW?
Space exploration. Part 6: More men in space: Project Mercury
Project Mercury (so-named for its image of speed) was the first US human spaceflight programme. Running from 1959–1963, its main goals were: putting a man into Earth orbit (ideally for at least a day), investigating human ability to function in space, and successful recovery of both humans and spacecraft. The programme included 20 un-manned launches and 6 manned missions.
Between August 1959 and November 1961, the preparatory un-manned missions were designed to test different components, including the launch escape system, booster rockets, and tracking network, and the system as a whole (using animals to evaluate survival mechanisms). The fifth un-manned mission was the first of four suborbital flights carrying primates.
Just large enough for one human crew member, it was said that the manned Mercury spacecraft were worn, not ridden. The first Americans in space were drawn from a group of 110 military pilots, chosen for their flight test experience and particular physical characteristics. The final selection made up the so-called ‘Mercury 7’, although medical problems meant that only 6 flew Mercury missions. The mission names included the rockets used for each flight.
Although planned for launch in 1960, engineering delays on the first US manned mission enabled the Soviets to be first to launch a man into space, in April 1961. In May 1961, watched or listened to by 45 million Americans, Alan Shepard became the first American to make a flight into space. The Mercury–Redstone 3 mission lasted 15.5 min., travelling a distance of 486 km and reaching an altitude of 187 km. Although he did not achieve a full orbit, as the Soviets had done, Shepard was the first human to safely return to Earth inside his vehicle (Gagarin parachuted from his vehicle prior to landing).
The second US sub-orbital flight took place in July 1961. Planned as a repeat of the first manned launch, the Mercury-Redstone 4 flight lasted just under 16 minutes, and reached similar altitude and distance as Mercury-Redstone 3 had. It included several improvements based on the experiences with Mercury-Redstone 3, including an explosive hatch release, a larger, single rectangular window, and modified manual controls. The successful water landing went awry when the hatch cover blew away, allowing water into the craft. The astronaut, Gus Grissom, managed to climb out and float on the sea to await pick-up. Flooding of the spacecraft made scheduled recovery impossible and it sank, finally being recovered from 4.5 km deep water 550 km south-east of Florida in 1999.
Mercury-Redstone 5 was an un-manned test mission which carried a chimpanzee on two Earth orbits. Delayed for over a month by technical problems and adverse weather conditions, in February 1962, Mercury-Redstone 6 successfully enabled John Glenn to become the first human American to orbit the Earth. The spacecraft completed 3 orbits in a mission lasting almost 5 hours: 2 orbits and 3½ hours longer than the Soviets had with Vostok 1, 10 months previously. The May 1962 Mercury-Atlas 7 mission replicated Glenn’s mission in length and time, but a targeting error during re-entry took the spacecraft about 400 km off course, delaying astronaut Scott Carpenter’s and the spacecraft’s recovery by several hours. There was a successful scientific focus in the mission, including study of the behaviour of liquids in weightless-ness, and photography of Earth and weather phenomena.
The third Mercury mission of 1962 lasted over 9 hours, making 6 Earth orbits. Although a record for the US, it was far off challenging the 3½ days which had been achieved by Vostok 3 earlier that year. The focus of Mercury-Atlas 8, piloted by Wally Schirra, was technical evaluation of the spacecraft and the effects of longer flight on the astronaut, rather than on scientific experimentation. Although interest in the mission was eclipsed by the Cuban Missile Crisis, all the engineering objectives were fulfilled, encouraging NASA’s plans for a full one-day orbit.
NASA finally achieved its ultimate goal of the Mercury programme with Mercury-Atlas 9 in May 1963, when astronaut Gordon Cooper remained in Earth orbit for more than 24 hours. The US had matched an achievement made by the Soviets almost 2 years earlier. The support logistics for a mission which would orbit over nearly all of Earth between 32.5 degrees North and South were extensive: 28 ships, 171 aircraft and 18,000 servicemen. Cooper undertook a number of spaceflight and other scientific experiments on his 34 hour mission.
The Mercury-Atlas 9 mission proved to be the final flight of the Mercury programme, as well as the final time the US would launch only one astronaut. Mercury-Atlas 10 had been planned as a 3 day mission, but, along with three other planned missions, in light of the consistent success of the 6 manned Mercury missions, it was cancelled, and NASA moved onto the more advanced two-man Project Gemini.
* Programmes highlighted in bold* are covered in other parts of this series
For more information on the Hermanus Astronomy Centre, visit our website at www.hermanusastronomy.co.za
John Saunders (Chairman) 028 314 0543
Steve Kleyn (Technical Advisor) 028 312 2802
Pierre de Villiers (Treasurer) 028 313 0109
Irene Saunders (Secretary) 028 314 0543
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Derek Duckitt (Website editor) 082 414 4024
Johan Retief (Monthly sky maps) 028 315 1132
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Lynette Geldenhuys (Education co-ordinator) 028 316 2428