Aurora - Dr Melanie Windridge – Wednesday 18th July 2018

MW Headshot.jpeg

Melanie Windridge has explored the science and mythology of the Northern Lights and this month she shared many of the stories of her quest to explore her fascination in and our understanding of the Earth’s Aurora. Melanie is a physicist, specializing in fusion research. She is also an adventurous traveler, particularly at home in the world’s coldest places.

She shared the experience of her visits to many places where the aurora is visible – Lapland, Iceland, Canada, northern Scotland, and Spitzbergen – and of meeting people for whom the Northern Lights plays a significant part of their lives. She travelled, for example, with Sami herdsmen in northern Norway and learned of Sami mythology and the gradual dwindling of their nomadic way of life.


Dr Windridge interweaved these stories with explanations of the science of the Northern Lights. Aurora occur when electrons and protons, which are charged particles and form the greater part of the solar wind, interact with Earth’s magnetic field and elements in the earth's atmosphere. Solar winds stream away from the sun at speeds of between 300 and 750 kilometers per second. They reach the Earth some 30 to 40 hours after leaving the sun. As the electrons enter the earth's upper atmosphere, they will encounter atoms of oxygen and nitrogen at altitudes from 20 to 200 miles above the earth's surface. The colours generated relate to the energy levels available in atoms that are struck. Nitrogen producesthe blue and purple and oxygen produces green and red.

The auroras generally occur in ovals which centre on the magnetic poles and roughly correspond with the Arctic and Antarctic circles. There are times, though, when the lights are farther south, usually when sunspot activity is high. Sunspot activity follows an 11-year cycle. The next peak will occur in 2022.

Melanie highlighted the dangers that space weather poses for satellites in orbit, and for the power grid on the Earth’s surface. She outlined her own efforts to view the aurora, illustrating with her best attempts to capture an image how difficult it is to photograph the aurora’s rapidly-changing structure.

Chris

Humans in Space – What’s Next? Libby Jackson – UK Space Agency

Humans first went into space in 1961, landed on the moon in 1969, and have been continuously living and working on board the International Space Station (ISS) since 2000. But where will we explore next?  This was the question UK Space Agency’s Libby Jackson posed at our lecture meeting this month.

The Moon landings were all about exploration (arguably, actually, they were all about politics!) – and in contrast the activities aboard the ISS are all about science, part of which is to understand the effects of prolonged exposure to space travel on humans. The next phase in space flight is reverting to exploration with visions of trips to the Moon and Mars. But we have enormous problems to overcome.

Propulsion for example. For the Moon missions the Saturn rocket could lift a payload of 40 tons for a two week trip. The ISS is the size of a 5 storey building and took many missions to build it to its present size and functionality, and is constantly being re-stocked. A journey to Mars will take 9 months, then 6 months there waiting for an appropriate planetary alignment before setting off back, and another 9 months to return to Earth. The resources needed for such a trip will require an approach to getting stuff into space some orders of magnitude greater than what we currently have. The advances made by the likes of Elon Musk and his Space X operation may be the way forward here.

Astronauts will need to be protected from solar radiation because unlike us on Earth, protected by the Earth’s magnetic field, they will not have such shielding either during their journey or whilst on Mars itself – Mars has lost its magnetic field, remember. Right now, no technology exists to provide such protection (putting them in a lead spacecraft, for example, is impractical due to the weight).

The physical well-being of astronauts in long terms space flights is beginning to be understood – in short, space travel causes instant ageing (for example Calcium very quickly leaches out of bones under zero gravity resulting in osteoporosis). Solutions to this and to have astronauts who can actually function on arrival at Mars, will need to be devised.

Landing will pose problems too – it’s a sobering thought that half of all Mars missions so far have failed in this regard. Mars has very little in the way of an atmosphere and the problem of opening a parachute in a near vacuum (if this were to be the mechanism chosen) has yet to be solved.

Communications at these distances is lengthy. At maximum Earth-Mars separation for instance it would take a radio message 24 minutes to travel one way. Astronauts on the ISS or even the Moon are accustomed to more or less instant communications. The Apollo 13 mission recovery required constant and immediate dialogue between the stricken spacecraft and Mission Control. A different level of autonomy and self-sufficiency will be needed by the astronauts.

And how would astronauts cope psychologically over a 2 year period eating dried rations and being out of direct communication with friends, family and Mission Control? Simulations of such conditions on Earth have been carried out so at least a partial understanding is being gained here.

Finally, there are ethical, legal and environmental questions which require solutions – bio-protection is an issue even here on Earth when we start exploring the Arctic for instance. Indeed should we even consider going to Mars, risking us contaminating the Red Planet, or even bringing Martian contaminants back to Earth?

It has taken almost 60 years to get to where we are in space exploration from when Yuri Gagarin became the first person to orbit the Earth. Libby Jackson highlighted the formidable gaps in our knowledge and technology to take the next steps in space exploration. Nevertheless she remained upbeat about overcoming them and was optimistic that in her lifetime she would witness humans on Mars.

Sandy

Developments in Gravitation and Cosmology - Professor Bob Lambourne, Open University

fullsizeoutput_1977.jpeg

Not since Galileo in 1610 made his ground-breaking discoveries using the newly invented telescope, have we been at such a scientific threshold - a new age of astronomy. Such was the view of our Vice-President, Professor Bob Lambourne, in his February 2018 lecture to our Society. For not only were gravity waves, originating from two colliding neutron stars 130 million light years away, detected on 17th August 2017 (GW170817) by the LIGO interferometers in Hanford and Livingston, and the Virgo interferometer near Pisa, but also parallel observations were made all across the electromagnetic spectrum.

Professor Lambourne started his lecture reprising material he had presented to the Society in February last year: Newtonian –v– Einsteinian theories of gravity, Interferometry and LIGO, a brief history of the universe. He then went on to describe the discovery timeline of that neutron star collision detection on 17th August last year.

1.7 seconds after the gravity wave event, a gamma ray burst was detected by the NASA/DoE Fermi space telescope. 6 minutes later the Virgo observatory confirmed the LIGO data (it had taken time because the Virgo detection was very weak, being close to one of the instrument’s blind spots). 40 minutes after the event, the gravity wave alert was sent out to the astronomical community. 5 hours later Virgo and LIGO data were combined to determine the source direction of the original neutron star collision – somewhere near the elliptical galaxy NGC4993 near γ-Hydra. Now optical telescopes could get to work and after 11 hours the Swope 1-metre telescope spotted the collision – the galaxy’s red shift (z = 0.009) put it at a distance of 130 million light years mirroring the gravitational wave data. 15 hours after the event, the Swift satellite reported a bright UV emission. 2 weeks later there was X-ray data. Interestingly, but rather disappointingly, the Ice Cube Neutrino Detector at the South Pole failed to detect anything.

All this takes place rather fittingly almost exactly a century after the birth of modern Cosmology; it heralds the birth of multi-messenger astronomy and hopefully will give us new insights to things like gamma-ray bursts, binary star evolution, heavy element synthesis – and, who knows, even dark matter! “There is a huge revolution in progress” Professor Lambourne concluded “This is a great time to be interested in astronomy”.

Sandy Giles

Variable Star Research using SuperWASP - Prof Andrew Norton, Open University

 Professor Andrew Norton and WAS' DR Sandy Giles

Professor Andrew Norton and WAS' DR Sandy Giles

Prof Norton and his colleagues certainly took advantage of the data harvested by SuperWASP telescopes when advancing our knowledge of variable stars. The Wide Angle Search for Planets (WASP) is an international consortium of several academic organisations primarily performing an ultra-wide angle search for exoplanets using transit photometry. Two continuously operating observatories in the Canary Islands and South Africa cover the Northern and Southern Hemispheres, and simultaneously monitor many millions of stars at magnitudes 8 to 15 using eight wide-angle cameras.

 SuperWASP

SuperWASP

(The telescopes are about fifteen years old now and Prof Norton amused us with the story that in the early days, while trying to eke out their research budget, they were compelled to buy the Canon 200 mm f1.8 lenses in just one’s and two’s. Unfortunately Canon stopped making them before the two telescopes were completed and all remaining stocks were bought up by a single buyer who put them up on e-Bay for sale. Fortunately they were able to persuade the university’s Purchasing Department to bid for them and hence complete the instruments!)

So though the primary aim of WASP was to monitor stars for exoplanets, there was a wealth of other data which could be put to good use on variable stars. And we’re talking big data here! Using a Linux computer cluster, initially 30 million stars were identified with apparent periods of variation. Then, using specially written software to automatically filter out unwanted interferences, 771,000 stars were found to have valid periods. And out of this work emerged a number of discoveries.

For example, 143 short period eclipsing binaries with periods of less than 5½ hours were discovered – only 12 were known previously. And the orbital period of many binary stars varies, which may be caused by the presence of a third massive body in the system. They studied the period variations in 13,927 eclipsing binary candidates and observed sinusoidal period changes, strongly suggestive of third bodies, in 2% of cases; however, linear period changes were observed in a further 22% of systems, likely to reflect longer-term sinusoidal period variations caused by third bodies. But this is only scratching the surface of how stars are organised. One binary pair turned out to be a doubly eclipsing quintuple low-mass star system, with a group of three stars orbiting another group of two!

So just as we are now discovering that planets associated with stars are in fact commonplace, it now seems single stars are in a minority, especially at higher masses. And the notion that binary stars have planets is not far-fetched either.

Much to ponder after this technical but, judging by the large number of questions asked, very engaging lecture.

Sandy

13 Journeys through Space and Time: Christmas Lectures from the Royal Institution - Colin Stuart

IMG_6595.jpg

When Colin Stuart asked the audience how many people had listened to the Royal Institution Christmas Lectures, a large number of hands went up. When asked how many had actually attended one for real, well, I put my hand up though I didn’t notice whether there was anyone else. Those of us who listened through our childhood to these lectures remember them with fondness, and certainly my interest and eventual occupation as a scientist owe much to the quality and enthusiasm of the selected speakers over the years.
 
Colin Stuart is an astronomy speaker and author whose books have sold more than 100,000 copies worldwide. He has written over 100 popular science articles for publications including The Guardian, New Scientist, BBC Focus and the European Space Agency. In recognition of his efforts to popularise astronomy, the asteroid (15347) Colinstuart is named after him.
 
The Christmas Lectures have run every year since 1825 (with a brief pause between 1939 and 1942 and between 2005 and 2006). They were the brainchild of Michael Faraday who gave the first one; his idea was that the talks should be aimed at children and should include as many practical demonstrations as possible. Colin Stuart set out to discuss thirteen of the lecture series over the years. But to a large extent, the actual content of those lectures was not the key point of interest. It was those snippets of science and the scientists that he learned about during his researches which provided the main fascination.
 

  • For example Robert Ball’s 1881 series. At that time Ball didn’t know what powered the Sun; the Moon, he stated, was too far away for Man ever to get there; there were canals on Mars. More fascinating was the fact that communications in those days were so slow that letters between scientists travelled too slowly to make important announcements (for example about sightings of comets). The scientists of the day devised an ingenious coding system employing a dictionary to exploit the Telegram Service to communicate this type of information.
     
  • Herbert Hall Turner in his 1905 lectures opined that Sun Spots were bruises inflicted on the Sun by Comets!
     
  • Harold Jones’s lectures on “Astronomy in our Daily Life” was the first to be recorded by Pathé. The rapt interest and enthusiasm shown by his young audience was no different from today’s youngsters.
     
  • In 1970, Sir George Porter used a model time machine. It was so large that a window in the Institute had to be removed to allow the model to be brought in and out using a crane!
     
  • The economies (or rather the lack of them) for Carl Sagan’s 1977 series drew some surprise, but the extract shown of Sagan entertaining two young audience members to afternoon tea on Mars was particularly heart-warming, just so typical of the very practical nature of all these lectures. Colin Stuart’s hunt for Sagan’s assistant, Dr Arun Aggarwal, was also charming.

Colin Stuart’s book (of the same title as this lecture) goes into a lot of detail and contains many fascinating and humorous stories about the lectures. This was a gentle, entertaining and confidently delivered lecture which our audience of about fifty enjoyed enormously.

Sandy.