We think the moon formed when a Mars-sized planet (Theia) smashed into the proto-Earth four and a half billion years ago. This remarkable idea is supported by the geology of moon rocks, brought back by the Apollo astronauts between 1968-1974, and by much more recent computer simulations.

But one puzzle remains: the relative proportions of oxygen isotopes are identical for Earth rocks and moon rocks. (Isotopes are different forms of an element that vary only in the mass of their atoms.) Originally this was taken to mean that the moon and Earth came from the same source — neatly supporting the impact hypothesis — until the computer simulations showed that most of the moon must be derived from Theia, not Earth. But Theia must have had a different proportion of oxygen isotopes to the proto-Earth.

This paradox is resolved by recent calculations. These show that the collision between Theia and proto-Earth was so violent that both bodies were extensively melted or vaporized and thoroughly mixed before Earth and moon condensed after just 1000 years. This eliminated variations in the proportions of oxygen isotopes.

This is exciting research as it implies that moon rocks may resemble the rocks of early Earth. Ironically we can't find rocks from Earth's earliest times here because plate tectonics and weathering has destroyed such ancient material. It seems that to learn about early Earth we should look to the moon.

Earth is constantly bombarded by high energy particles from space, cosmic rays. Most are protons, the positively-charged particles that normally live in the nuclei of atoms. Many come from the sun, but the highest energy cosmic rays are an enigma. Some have scarcely believable energies, way beyond what could be produced by any conceivable particle accelerator here on Earth. We do not know where they came from, how they could get here, and we have no idea what process could give them such stupendous energies. Now a new observatory has allowed a collaboration of over 300 scientists to answer the first of these questions.

With an array of 1600 detectors that stretch over 3000 km2 of Argentina, the Pierre Auger Observatory detects the showers of particles generated when high energy cosmic rays whack into air molecules. The researchers have discovered that the origin of the highest-energy cosmic rays are quasars. All galaxies have black holes at their centre. In some galaxies gas and stars are falling into the central black hole and prodigious amounts of energy are radiated out as a result, turning the nucleus of the galaxy into a brilliant quasar. How quasars could generate such high energy cosmic rays is a total mystery.

Probably the best known - or at least the most photographed - of the weathervanes at the ROG is that which sits on top of the time ball on Flamsteed House. But there are two others that are worth a closer look. They date from the turn of the last century and, as well as being decorative, make interesting allusions to aspects of the Observatory's history.

The first one that you come across as a visitor is on the Altazimuth Pavilion. It is modelled on Halley's Comet, as depicted in the Bayeux Tapestry. It was erected in June 1901, a few years after the building was completed but in time for the comet's return in 1909. There is a clear link with the Observatory's history since Halley was the second Astronomer Royal, although his famous prediction was made fifteen years before he took up the post. It is not clear why the illustration from the Bayeux Tapestry was used as inspiration, although its shape is ideal for catching the wind and echoes that of the weathervanes of the Royal Naval College down the hill.

Weathervane depicting Halley's Comet

The second vane is sited on top of the dome of the South Building, or the New Physical Observatory as it was once known. This building was erected in stages between 1890 and 1899, with the vane being completed in March 1897. This time the allusions to the Observatory's history are a bit less obvious, for it depicts a ship.

Weathervane on the South Building

However, it is not any old ship, but Henri Grace a Dieu, or the Great Harry, a flagship of Henry VIII that was probably the most famous historical vessel before the Mary Rose's resurrection stole the limelight (as suggested by the NMM's collection of prints of this ship.) A bit of digging brings up references that remind us that the original purpose of the ROG was to solve a navigational problem and that throughout the 19th century it was administered by the Admiralty. Henry VIII had founded the Admiralty and the Great Harry's master, Thomas Spert, was the first Master of Trinity House, a foundation that had the safety of seafarers at its heart. In addition, there is a local reference as the ship was built at Woolwich. The naval links are brought out elsewhere in these buildings, particularly in the rounded 'porthole' windows below the domes - for both were designed by William Crisp, an engineer in the Admiralty's Department of Works. The ROG's modern link with the NMM, as well as its history, means that this nautical theme is still entirely appropriate.

In the last few weeks I've been asked about Thomas Cooke (1807-1868) and whether he should be commemorated in some way. Each time my answer has been a resounding yes. Although he's not well known today, his is an inspiring story.

Born in Allerthorpe in the East Riding of Yorkshire, Thomas was the son of a shoemaker. Then in his youth he became inspired by tales of Captain James Cook (no relation) and resolved to go to sea by teaching himself mathematics and navigation. It is said, however, that his mother's tears over the dangers she foresaw caused him to change his mind and turn his attention to optics and making telescopes. This was something he became very good at. After setting set up a firm in York, he gained a worldwide reputation for the quality of his refracting telescopes (which use lenses to gather light).

Portable refracting telescope by T. Cooke & Sons, the firm Thomas Cooke created

As well as winning prizes at international exhibitions, Cooke's telescopes also proved their worth in astronomy. His work included the mount for a telescope William Huggins used for ground-breaking work in spectroscopy, the telescope Norman Lockyer used for work in the same field, and what became the largest telescope in the world (for a short while) - the Newall telescope. This had a main lens of 25 inches in diameter and was made for Robert Newall, a rich industrialist with a private observatory at Ferndean near Gateshead. Sadly, the weather there was too poor for good observing, and the telescope went to Cambridge University's observatory after Newall's death. Then in the 1950s it travelled to the Greek National Observatory in Athens, where it is still in operation.

In his lifetime, Thomas Cooke helped to bring Britain back to the forefront in optical manufacturing, an area in which German and French firms had begun to take over. His firm built telescopes of outstanding quality that were used in many professional and private observatories and which underpinned important astronomical work. His contribution to Victorian science is certainly worthy celebrating.

The 'onion' dome for the Royal Observatory's 28-inch telescope was designed and built by Cooke & Sons

While researching a book I've been writing on the history of the telescope, I've come across a number of humorous prints like this one, Robert Sayer's Viewing the Transit of Venus of 1793.

It is one of the many satirical prints produced in England in the 18th century and seems to show a well-heeled couple observing Venus as it passes between the Earth and the Sun. So at first glance this appears to be just the sort of message that science's supporters were putting out - that science was worthy of study by the more learned and 'polite' members of English society.

But if we look closer, something rather different is going on. The scene isn't topical at all - the most recent transit of Venus had taken place over twenty years earlier in 1769. And the statue of the satyr on the right hints at rather more sexual interests, emphasised by the way in which the man lightly fingers the telescope, suggesting that it is akin to what contemporaries called the 'staff of life'. Perhaps he is hoping for a more bodily transit of Venus, recalling stories of the amorous encounters of the Greek goddess of love. This telescope, then, has become a most impolite instrument.

Keep coming back for more Telescopes stories throughout the International Year of Astronomy 2009.

This week H1 is to be dismantled for repairs in the conservation workshop here at the Royal Observatory. The Harrison timekeepers are so popular that they're rarely off display.

Harrison's first timekeeper, H1

The problem with the timekeeper occurred last year when the connection broke between one of the balances and its lower balance spring. The balances and springs are the vital 'beating heart' of the timekeeper, and being complete and well adjusted is fundamental to the good going of the instrument.

H1's right balance and its broken spring connection

As Senior Specialist in Horology at the Museum it's my job to undertake this exciting and delicate work, and it was with some trepidation that we prepared H1 for its 40 metre trip yesterday morning to the workshop. It's now on the 'operating table' (a medical trolley we use for transporting) and my first task is to take photographs all round the timekeeper before any dismantling takes place.

During the work, there is a screen set up in H1's showcase with a short slide show telling visitors what's happening. If staffing allows, the on-going work on H1 can be seen from the Time for the Navy gallery, which is next to the workshop and has a glass-backed showcase through which parts of the workshop can be viewed.

Working on H1 is going to be very special for me as one of my great heroes in the Harrison story is Lt.Cdr R.T.Gould, who rescued the timekeepers from oblivion back in the 1920s and 30s. It was almost 90 years ago, in 1920, that he first started that work. I'll be contributing two or three entries a week to this blog, so keep an eye out if you're interested!

Dismantling of H1 has progressed smoothly this last week, and there has been considerable interest in the project from colleagues and the public. Last Thursday the Guardian newspaper's delightful Maev Kennedy paid us a visit with photographer David Levene, and an extraordinary double page 'centrefold' picture appeared in the paper on Monday with H1 pictured from a fascinating and engaging angle. If I'd known my rough notes, visible next to the timekeeper, would be readable in a national newspaper I'd have tried to make them less inscrutable!

Also on Monday we had a visit from the current students and tutor, Matthew Read, from the Clock Course at West Dean College, who were duly impressed by being able to inspect H1 partially apart, and were consequently able to better understand some of its intricacies.

So far, the dials are all off and the front plate has been removed, revealing the 'motion work' (the gears which ensure the hands go round at the correct rate). The calendar wheel had a particularly lovely surprise, in that I found Harrison had decorated the little part on the wheel called the 'jumper' with a most beautiful, rather Celtic style tail and with a front end shaped in the form of a little bird's head!

None of this can be seen when the clock is complete of course, and it must have been included entirely to please himself, and future clockmakers. Well, it certainly pleased me John!

Next will be the main train of wheels and all their roller bearings; it will be interesting to see if much wear is evident after nearly half a century of virtually constant running.

Today has been designated Ada Lovelace Day - an international day of blogging to draw attention to women excelling in technology. It is named after Byron's daughter, Ada Lovelace (1815-1852), the mathematician who is credited with writing the first ever computer programme for Charles Babbage's Analytical Engine, a never-completed computing machine. Taking the idea of technology broadly, I thought this would be a good opportunity to begin a series of occasional blog entries on women connected to the ROG throughout its history.

The first woman who was seriously involved with life and work at the ROG was the wife of the first Astronomer Royal, Margaret Flamsteed (c.1670-1730). She was the daughter of a London lawyer, Ralph Cooke and granddaughter of John Flamsteed's predecessor as rector of the Surrey parish of Burstow. She was probably baptised in Hackney in 1670 making her about 22 when she married the 46-year-old Astronomer Royal on 23 October 1692. Despite the age gap, there seems to have been a sincere attachment between the two, if the words 'beloved Wife' in Flamsteed's will and Margaret's determination to secure her husband's pothumous reputation are anything to go by.

The Royal Observatory from Crooms Hill, in about 1680 - the time that Margaret Flamsteed began living there.

Margaret Flamsteed was clearly a well-educated woman, both literate and numerate. We know from Flamsteed's records that she was occasionally of practical assistance during observational and calculating work, and manuscripts in the RGO archive in Cambridge record her study of mathematics and astronomy. These studies may have reflected those undertaken by Flamsteed's paid assistants and paying pupils - men and boys that Margaret would have taken care of as part of her general management of the household on Greenwich Hill. She seems to have been a particular asset when acting as hostess to the Observatory's visitors, no doubt smoothing over her husband's sometimes prickly temper.

It is, however, as Flamsteed's widow that Margaret is best remembered. Firstly she worked with the Observatory's former assistants to publish the full version of Flamsteed's book, Historia Coelestis, an abridged version of which had, to Flamsteed's fury, been published by Edmond Halley in 1712. Rather more sadly for us, she also removed and sold all of the astronomical and horological equipment that Flamsteed used at the Observatory. This she was probably justified in doing, as Flamsteed had either paid for the equipment himself or had received it as a personal gift from his patron Jonas Moore. It was to take several more Astronomers Royal before the questions of ownership and copyright that dogged the Flamsteeds were sorted out.

Today, I'm pleased to say, sees the publication of a new book I've written on the history of the telescope. The book has been brought out in celebration of the International Year of Astronomy 2009 and to mark the 400th anniversary of the invention (or at least the announcement) of the telescope in 1608.

I've tried to tell as broad a story as possible. So I've talked about the development of telescopes for astronomy and their huge impact in changing our conceptions of the universe but I've also looked at the more humble story of the hand-held telescopes and binoculars used for all sorts of things on land and at sea. If you think about it, after all, most of the telescopes ever made were for these more mundane purposes. Another aspect I've included is the cultural impact of the telescope, whether as a symbol in art and literature, or as an inspiration for science fiction and other writers and film-makers. So as well as Galileo, Newton and Hubble, you'll find Alfred Hitchcock, H.G. Wells and Virginia Woolf. And don't forget to look out for Tom Swift and his megascope space prober.

For those wanting to look even deeper into the telescope's history, you may also be interested in a forthcoming conference, The Long View, this July.

Dismantling of H1 has progressed well and the timekeeper is now almost totally in pieces. As parts come off I'm taking the chance to look at them closely and am developing a much more detailed idea of the restoration carried out by Gould and the Chronometer Section in the 1960s.

In spite of his descriptions of the restorations in his notebooks, Gould did not provide complete data, and I am now busy counting teeth on wheels, measuring parts and keeping a tally of the total number of parts in H1. Some statistics are proving quite surprising. For example, just the two fusee chains (which link the driving springs with the wheels of the clock) between them total almost 4,000 bits!

Now that the wheels and roller bearings are all out it is becoming clear that the timekeeper is in very fine condition. Almost no wear is perceptible on the bearings, and Harrison's 'rolling contact' arrangement has stood the test of time extremely well. The only evidence of long use is what one might call the 'computer mouse' problem, where the rolling contact has caused thin layers of dust to become compacted on the rollers (just as it does inside the mouse sometimes).

Next is extensive photography and measuring, and I have to decide on the best (and most conservative) way to repair the broken balance spring connection.

Continuing the theme of women connected to the ROG, this post leaps forward from Margaret Flamsteed in the 17th century to Annie Scott Dill Russell, in the 19th. Hired as a 'lady computer' at the ROG in 1891, Annie spent five years calculating and observing at Greenwich. In 1895 she then married E. Walter Maunder, the ROG First Assistant in charge of the Photographic and Spectroscopic Department. And, unusually for this period, marriage did not spell the end of her career in astronomy.

Annie was born in County Tyrone in 1868, and was educated at home and at the Ladies' Collegiate School in Belfast before gaining a scholarship to Girton College, Cambridge, and graduating with second-class honours in the mathematical tripos of 1889. She spent a year teaching mathematics before, in September 1891, she was hired to work at the ROG as one of the few female 'supernumerary computers' - those hired on a short-term basis rather than being permanent members of staff.

Usually computers were boys, arriving straight from local schools. But hiring women allowed William Christie, then Astronomer Royal, the luxury of gaining well-trained mathematicians at a cheap rate (they were paid about £4 a month, rising to £6 as 'soon as efficiency in the use of the Photographic Equatorial is acquired'). The experiment was something of a stop-gap, for Christie was in the process of persuading the Admiralty to increase the Observatory's (male) workforce. There may also have been a shortage of women prepared to accept the low wages: as Annie wrote, it 'is so small that I could scarcely live on it'.

Annie resigned her post in 1895, in preparation for marriage, although she did return to formal duties at Greenwich as a volunteer during the First World War. In between these periods she continued to pursue her interests in practical astronomy, receiving a small grant from Girton College to make a photographic study of the Milky Way. However, it was her husband's connection with Greenwich and her involvement with the British Astronomical Association that allowed Annie access to the equipment and resources needed for serious astronomical work.

She accompanied Walter on several eclipse expeditions and worked with him on the periodicity of sunspot activity, as well as publishing a number of books and papers under her own name or jointly with her husband. These included a catalogue of some 600 recurrent sunspot groups observed and photographed at Greenwich (1907), and The Heavens and their Story (1910). She was also editor of the BAA's journal for 15 years.

Annie Maunder (centre) preparing to observe the 1900 eclipse in Algiers with the British Astronomical Association (from E. Walter Maunder (ed.), The Total Solar Eclipse of May 1900).

In 1916 Annie became one of the first female fellows of the Royal Astronomical Society. She survived her husband by almost 20 years and late in life became an authority in ancient astronomies. Although she lived in Greenwich for at least 33 years, she later moved to Wandsworth, where she died in 1947.

While looking into the history of the telescope, I've been struck by the number of images that, perhaps unsurprisingly, show it symbolically as an instrument of revelation and learning. One of my favourites is this detail from the frontispiece to Johannes Hevelius' Selenographia of 1647.

Hevelius (1611-87) was from a brewing family from Danzig (now Gdańsk, Poland), gaining further riches from his marriage to Katharine Rebeschke, whose family lived next door. Being so well off, he could indulge his passion for astronomy by building large telescopes for his personal observatory, which spread across the city's rooftops. One of the things he did there was to spend four years making detailed, and very beautiful, maps of the Moon, which he published in the Selenographia. His very fine observing skills and artistic talent, not to mention the quality of his telescopes, meant that these were the best lunar maps available for a century.

This detail from the book's frontispiece symbolically shows how the telescope fitted into his work and thinking.

In the centre is the figure of Contemplatio, covered in eyes and carried aloft by an eagle. Both these figures are significant. 'Contemplatio' can be translated as contemplation, but also as viewing or surveying, while the eagle represents both vision and ascension. Contemplatio is also holding a telescope in her right hand and is using it to sweep away the clouds of ignorance. Behind her are the Sun and Moon as revealed by the telescope, with sunspots clearly visible. Beneath Contemplatio, two putti hold a banner with a biblical quotation from Isaiah, which translates, 'Lift up your eyes on high and behold who hath created these things.' To Hevelius, then, the telescope is an instrument that reveals the truth about a (Christian) created universe, the contemplation of which is a spiritual journey in itself . His telescope is a weapon of intellectual and spiritual advancement.

If you are interested in Johannes Hevelius and his astronomical work, you can find out more at our forthcoming conference, The Long View.

This Sunday sees the 150th anniversary of the starting of the Great Westminster Clock, popularly known as Big Ben after its great bell. While Parliament is enjoying this anniversary (see http://www.bigben.parliament.uk/), it seems timely to remember the ROG's connection to these events. 

Edward John Dent, engraving by Charles Baugniet, 1853.

 
The Westminster Clock was built and designed by Edward John Dent, who made many of the clocks used by the ROG and now in the NMM collections. His recommendation as maker, and much of the design was, however, suggested by George Biddell Airy, the 7th Astronomer Royal. 

George Biddell Airy, engraving by Thomas Herbert Maguire, 1852

Airy had frequently collaborated with Dent on Observatory equipment and to try out his own ideas in clock-making theory. Not least, they had already collaborated on another important turret clock, which was made for the Royal Exchange. This was so successful that Dent remarked, "The mechanical world in my opinion lost its greatest genius when Mr. Airy became an Astronomer....".
 
Perhaps most importantly, from the ROG perspective, it was Airy who drew up the specification to which both the Royal Exchange clock and the Westminster clock should conform. They were to be far more accurate than previous public clocks of this type, for Airy specified that the first stroke of each hour should be accurate to a second. This was to be regulated to Greenwich Time, by being checked twice a day at the ROG via telegraph. As historian of science Jim Bennett explains, Airy not only devoted a lot of time to these clocks, but "it is clear that his general intention was not simply that another clock should be built, but to effect a change of attitude to public timekeeping". 
 

Westminster Clock Tower, watercolour by William Lionel Wyllie (late 19th/early 20th century)

Things did not proceed quite as easily as they had with the Royal Exchange clock and, perhaps because of lack of time, Airy asked the MP and amateur clock-maker Edmund Beckett Denison to assist in overseeing the project. Differences between the two led to Airy resigning in 1853 - but his demand for accuracy and the link to GMT remained.

See the UK Parliament website for an account of the various other delays that hit the building of the clock, the tower and the bell - and you can see some fantastic images of the Clock Tower and the workings of the clock on the BBC website.

Looking at the collection of telescopes in the Royal Observatory, it's notable just how many hand-held instruments we have. This is mainly because although we usually think of the telescope as an instrument for astronomy, most of those ever made were for far much more earthly purposes. And to their makers and sellers they were above all commercial products.

Portable telescope by George Willdey, about 1710

This now slightly damaged telescope is one of our decidedly commercial examples. It was made in about 1710 by a London maker called George Willdey. With its black shagreen barrel, gold-tooled green leather draw tubes and ivory fittings, it was obviously a luxury item for the rich and fashionable of the metropolis.

This point becomes even clearer when you look at the range of stuff Willdey sold, shown in one of his advertisements from the same period.

Advertisement for George Willdey's shop

At the time, all these different items would have been classed as 'toys', meaning not children's playthings but small fashionable items for adults, such as fans, snuff boxes, writing tools and game pieces. Willdey's advert shows quite beautifully that the telescope could be not just a tool of science, but also a firmly commercial luxury item.

You can hear more about George Willdey and his telescopes at our forthcoming conference, The Long View, in July.

As a great film fan, I've had enormous fun over the past couple of years trying to spot telescopes in the movies, and have been able to call it research for the book the Museum recently published on the history of the telescope.


One of my favourite is an early film called As Seen Through the Telescope, directed in 1900 by George Albert Smith. It's a simple tale in which a dodgy old man uses his telescope to have a good look at a couple across the street. It's also interesting as an early example of action cut across successive shots, with the viewer sharing what he sees: the young man's hands caressing the woman's foot and ankle, shown within a circular mask to mimic the telescopic view. In case you're worried, the voyeur doesn't go unrewarded - at the end of the film the younger man punches him. Perhaps that's why it was called L'astronome indiscret in France.

For those with time to spare, here are some of the telescopic films I've enjoyed:
Rear Window - A classic Hitchcock which explores the ethical issues raised by our irrestistible urge to peek at our neighbours
A Short Film about Love - Krzysztof Kieslowski takes on the same issues with less laughs
Notorious - another great Hitchcock. Check out the scene at the races - a witty touch with the binoculars
Storm over Mont Blanc - Leni Riefenstahl falls in love with a meteorologist, saves his life and abandons her large telescope for the kitchen
Contact - Jodie Foster wrestles with science, faith and telescopic evidence
The Dish - you'll believe a radio telescope can be a film star
Pirates of the Caribbean: At World's End - not the greatest film, but it does use telescopes for some really unsophisticated humour

For those interested, I'll be talking about some telescopic film stars in a couple of weeks at our conference, The Long View: 400 Years of the Telescope.

Back in April we met Annie Russell Maunder, but she was not, in fact, the first woman to be paid for her work at Greenwich under Astronomer Royal William Christie's new scheme. Russell's friend Alice Everett (1865-1949) had begun work as a supernumerary computer almost two years earlier, in January 1890.

Like Russell, Everett had attended Girton College, Cambridge and took the Mathematical Tripos, which essentially made both women as well-qualified as the Chief Assistant, Frank Dyson, who began work in 1894. Before this Everett had also attended Queen's College, Belfast, where she had taken first place in the first-year scholarship examination - causing the college authorities to question and decide against the eligibility of women in the competition.

At Greenwich, Everett was assigned to work in the Astrographic Department, contributing to the international Carte du Ciel project which aimed to map the skies using the still-new technique of stellar photography. Although her job-title was 'computer' (i.e. those who carried out routine calculations to 'reduce' raw observational data into usable tables), Everett was in fact trained to use the Observatory's new astrographic telescope in order to take the photographs, as well as then measuring the plates, calculating the co-ordinates of the stars and reducing the data for the catalogue. She also made observations for the Transit Department with the Prime-Meridian-defining Airy Transit Circle. Everett necessarily worked at the ROG at night, though we don't know whether she made her way through the park or stayed on-site when it was dark.


The Royal Observatory, Greenwich's astrographic telescope

Again like Russell, Everett was proposed but rejected for fellowship of the Royal Astronomical Society and instead found an outlet for her enthusiasm in the amateur British Astronomical Association, although she published in the Monthly Notices of the Royal Astronomical Society as well as in the BAA's journal, The Observatory and elsewhere.

After five years at Greenwich, Everett moved to the observatory in Potsdam, Europe's leading institution for astrophysical research, to continue work on the Carte du Ciel. This was only a temporary post, and after three years Everett was on the move again, this time for a year at the observatory of Vassar College. She failed to find another post in the USA and returned to London in 1900, where her interests turned to optics. She undertook a translation of a German optical text and carried out a number of experiments, but was unable to find regular paid work until the First World War, which gave many women an opportunity to enter the workforce. In 1917 she joined the staff of the National Physical Laboratory, where she remained until her retirement in 1925.

Even after retirement, Everett did not sit still. She took qualifications in electrical engineering and became involved with the Baird Television Company and Television Society, associations that were to last for the rest of her life. On her death in 1949 she left her library of scientific books to the Television Society.

For more information on and pictures of both these remarkable women, see Mary T. Brück, 'Alice Everett and Annie Russell Maunder torch bearing women astronomers'.

23 Feb 2010 - the Royal Observatory, Greenwich, in partnership with Zooniverse and Rutherford Appleton Laboratory, today launched Solar Stormwatch. This exciting web project allows anyone to help spot explosions on the Sun and track them across space to Earth. If you get involved your work will help give astronauts an early warning if dangerous solar radiation is headed their way - and you could make a new scientific discovery.

Solar Stormwatch uses archive and near real-time data from NASA's STEREO mission, a pair of spacecraft orbiting the Sun. Each spacecraft carries a Heliospheric Imager (HI) containing two cameras, creating a massive field of view stretching across the 150 million km from the Sun back to the Earth. Mission volunteers will be looking at these images to spot huge explosions from the Sun's surface - these are the solar storms, or more technically Coronal Mass Ejections (CMEs). These storms throw out about a billion tons of hot solar gases at a million miles an hour, representing a serious radiation hazard to both spacecraft and astronauts. They can knock out communication satellites, disrupt sat nav and mobile phone networks and damage power lines. Solar Stormwatch will help minimise this disruption by providing real-time alerts to those in the firing line, such as the crew of the International Space Station.

Multiple volunteers will look at each batch of STEREO data, and and if several independently confirm an interesting find it will be flagged up to a solar scientist.

Chris Davis, one of the solar scientists on the project team, says: "With your help, we can analyse many more events and do so in a way that is free of the subjective bias introduced by one person sat in his office making arbitrary decisions... Together we can use STEREO images to learn what it takes to make an accurate forecast of space weather conditions. Space exploration will always be a risky business but with an accurate space-weather forecast, astronauts will have one less thing to be worrying about as they leave the relative safety of Earth orbit and start to explore our solar system."

You can get involved now at www.solarstormwatch.com

Images: Artist's impression of the deployment of the STEREO spacecrafts' solar panels (NASA/Johns Hopkins University Applied Physics Laboratory); Coronal mass ejection taken by the SOHO spacecraft, 2002 (SOHO, NASA and ESA)

For the last few weeks, H2 has been in the horology conservation workshop at the Royal Observatory undergoing research. The work, which is part of the continuing research for a full published catalogue of the NMM's collection of marine chronometers, involves the complete dismantling of the timekeeper. Every part is being studied, measured and photographed, the intention being to take a fresh look at Harrison's work on his longitude machines.

Last year H1 was dismantled and studied, and some interesting comparisons can now be made about Harrison's early work. It has always been believed that the simple portrayal of Harrison as a lone craftsman, was too simplistic, and we know that H1 was constructed with the help of Harrison's brother James, and almost certainly with advice and supplies from George Graham's contacts in London.

Harrison is known to have had help in his construction of H2, which was made in London, and the current study confirms this, with a much more professional feel to the materials and the finishing of this timekeeper; if H1 is a reminiscent of a fascinating 'country clock', then H2 has all the trappings of a 'scientific instrument'.

There is no doubt Harrison had help in construction, but this doesn't diminish the status of this extraordinary timekeeper, which teems with interesting 'Harrisonian' designs and construction features.

The timekeeper is now completely dismantled and before reassembly can begin there is full photography and measurement for CAD drawings to be done. Analysis is also planned on both the special alloys and the wood used in the timekeeper. It has always been said that the latter is lignum vitae, but as far as is known this has never been positively proved before.

Further updates will follow before the timekeeper returns to exhibition in the Longitude Gallery, now estimated to be sometime in late July.

Many people have remarked on the two beautiful pictures of the Aurora Borealis or Northern Lights which feature in our current Astronomy Photographer of the Year exhibition. Anyone who's been lucky enough to see the aurora for themselves will know what a beautiful spectacle it can be, so it's not surprising that we had quite a few photos of it entered into this year's competition (which made the judging very tricky).

Earth's aurorae are ultimately caused by the Solar Wind, the stream of energetic particles emitted by the Sun. Funnelled down towards the North and South Poles by the our planet's magnetic field, these particles strike molecules of air high up in the atmosphere, causing them to glow and produce a shimmering display of lights. Because of this, aurorae are most commonly observed at high northern and southern latitudes and indeed both of the award-winning aurora photos this year were taken close to the Arctic Circle: one from Canada and one from Norway.

At the Astronomy Photographer awards ceremony on September 9th I found myself chatting to photographer Max Alexander who mentioned that some years ago he'd taken a picture of an unusual aurora while working in Sweden. I was very curious to see his photo and Max has kindly agreed to let us post it here on the ROG blog. 

Max says: 

"I took this photograph of the Northern Lights while on assignment for a book publisher to photograph the Ice Hotel, in Kiruna, Northern Sweden, a perfect latitude from which to view them. 

"After several unsuccessful nights looking up, I met a couple who invited me to their wedding ceremony in the adjacent Ice Chapel, and subsequent reception. Every so often, I looked out of the window to see if the Northern Lights would appear - and then they did, in all their breathtaking glory. I convinced the wedding party to go out into the freezing arctic air, and they were not disappointed. For twenty minutes there were audible gasps, as the aurora borealis first snaked slowly, then rapidly danced across the sky in giant and dazzling green arcs. I set my camera up quickly on my tripod, opened up the aperture fully on a wide-angle lens, and then made a series of 15 second exposures. Technically not difficult, I just needed to nail the composition.

"Back in London, The Independent used one of those photographs on the cover of their magazine, for a piece about Norwegian scientist Kristian Birkeland, the first person to provide a scientific explanation of aurorae. I also contacted the University ofLondon Observatory about what caused this phenomenon and from that conversation I ended up doing a diploma in astronomy at UCL, which in turn led me to take a series of photographs on astronomy in the UK, entitled Explorers of the Universe.

"I have reliably been told that this is a very rare photograph of the intertwining twister effect that you can see and Patrick Moore is the only person I have asked who has seen it in a photograph before. Mike Lockwood, a solar-terrestrial scientist at theUniversity of Southampton, explained to me that the aurora usually occurs in extended, curtain-like sheets. However, sometimes, as here, it is restricted to a small rope-like form. The currents flowing down the centre of such "auroral filaments" cause the surrounding magnetic field to twist up into the helical forms that can be seen here. The direction of the twist in this image shows that the dominant current was upward.  In other cases the current can be downward and the twist would then be in the opposite direction.

"By the way, the couple who got married have since become good friends of mine, and the pictures of the Northern Lights are part of their wedding photographs."

As the Sun continues to move into a more active phase of its eleven-year cycle we can expect to see more auroral displays as increased solar activity launches storms of particles in our direction. The Royal Observatory has a long history of observing activity on the Sun and our Solar Stormwatch citizen science project allows members of the public to help continue that research in the 21^st Century (and also links to a great gallery of aurora images).

Finally, it's worth pointing out that the Northern and Southern Lights are not just an Earthly phenomenon, as these spectacular new images and movies of aurorae flickering around the poles of Saturn show. The data come from NASA's Cassini spacecraft and we're very pleased that Tom Stallard and his team at the University of Leicester have allowed us to incorporate some of the images into the Saturn option of our Solar System planetarium show Meet the Neighbours. So if you'd like to see the Saturnian aurora in all its glory up on the dome come along to the show and vote for Saturn as your destination.

Earlier this month we launched a new blog and website. This will bring you the latest news on a five-year research project on the British Board of Longitude, which oversaw the successful introduction of effective methods for position-finding at sea (among other things, as we will show).

The project is a collaboration between the National Maritime Museum and the Department of History and Philosophy of Science at the University of Cambridge and is supported by a grant from the Arts and Humanities Research Council. We'll be updating the blog regularly, so keep checking for the latest progress and news of events and activities.