Moon Landing + 51

2020-07-20 09.20.29

The 51st anniversary of the Moon Landing comes around with the world in an even bigger mess than it was in twelve months ago.

We’ve also lost pioneering Russian cosmonaut & space walker Alexei Leonov.

Perhaps the most positive development has been the first crewed flight of SpaceX’s Dragon spacecraft.

Alexei Leonov (1934-2019)

Russian cosmonaut Alexei Leonov,the first human to walk in space, has died in Moscow aged 85. One of the legendary pioneers of the first decade of crewed spaceflight, he later commanded Soyuz 19 as the Soviet part of the Apollo-Soyuz Test Project. Following the announcement by the Russian space agency Roscosmos, NASA interrupted its live coverage of a spacewalk outside the International Space Station to report his death.

Although I’ve been fascinated by science, astronomy, and spaceflight since at least the age of five I have little memory of the early spaceflights, but Alexei Leonov’s spacewalk on 18 March 1965 sticks very strongly in my mind. It was just after lunch at school when a teacher told us that a man had walked in space from the spacecraft Voskhod 2 and the class was given the unusual (in a school where there was pretty well zero interest in science) and extremely welcome assignment of painting a picture of the event.

The extraordinarily rapid pace of developments in spaceflight was a product of Cold War rivalry between the United States and the Soviet Union. Thanks to the efforts of Chief Designer Sergei Korolev, the Soviet space program had racked up a remarkable series of ‘firsts’ including the first artificial satellite (Sputnik 1), the first photographs of the far side of the Moon (Luna 3), and most dramatic of all, the first human in space (Yuri Gagarin). The United States was galvanised into a response – in 1958, Eisenhower signed the National Aeronautics and Space Act, establishing NASA; and in 1962 Kennedy made his famous speech committing the United States to reaching the Moon before the end of the decade.

By the end of 1963, six Russians and six Americans had flown in space, all of whom had flown solo (to this day, Valentina Tereshkova remains the only woman ever to have gone into space alone). Following the conclusion of the successful Mercury program, the US was now working on Gemini, a spacecraft that would carry a crew of two and intended to pave the way for the Apollo Moon-landing project. The Russian response was Voskhod, which basically involved shoehorning three cosmonauts into a modified single-seat Vostok spacecraft. Safety features including ejector seats and spacesuits were omitted to save space. Despite this, the Voskhod 1 mission on 12 October 1964 was a success, though the flight only lasted just over a day. It was also an eventful day back on Earth: Soviet leader Nikita Khrushchev was deposed and replaced by Leonid Brezhnev.

As intended, the mission sent a strong message to the Americans that the Soviet space program meant business, and the Russians still hadn’t finished. Thus, on 18 March 1965 at 07:00 UTC, Voskhod 2 was launched from Baikonur Cosmodrome. On board were mission commander Pavel Belyayev, 39, and Alexei Leonov, then aged 30. Instead of a third crew-member, Voshkod 2 was equipped with an inflatable airlock.

Ninety minutes after liftoff, Leonov exited the spacecraft via the airlock to perform his epoch-making EVA. In his own words “I stepped into that void and I didn’t fall in. I was mesmerised by the stars. They were everywhere – up above, down below, to the left, to the right. I can still hear my breath and my heartbeat in that silence.”

Only much later was it revealed just how close the essentially makeshift mission had come to disaster. The inflatable airlock was necessary because Voskhod 2’s instrumentation had not been designed to operate in a vacuum, and hence the spacecraft itself could not be depressurised. When, after an EVA of 12 minutes, Leonov attempted to return to the spacecraft, he found that his spacesuit had ballooned and its joints had consequently stiffened to the point where he could not re-enter the airlock. He was forced to take the drastic step of bleeding off air from the spacesuit, to below safety limits, before he could bend the suit’s joints. The problems did not end there. There were difficulties in resealing the hatch after the spacewalk, and problems during re-entry resulted in Voskhod 2 landing 386 km (240 miles) away from the intended landing site. Leonov and Belyayev spent an uncomfortable night in the forests of Upper Kama Upland at temperatures of -5 degrees Celsius before a rescue party arrived the next day.

Gemini made its first crewed flight just days later, on 23 March, and its second between June 3 and June 7. On this second flight, on June 3, Ed White became the first American to perform an EVA. Alexei Leonov’s space walk would be the last time that the Russians would beat the Americans in space. Leonov was slated to land on the Moon in a craft known as the LK (‘Lunniy korabl’, or lunar craft), which was basically a much smaller single-seat version of the US Lunar Module. But the mission never took place: problems with the N1 rocket and Korolev’s death early in 1966 finally ended Soviet hopes of beating the Americans to the Moon. The Russians turned their attention to space stations in low earth orbit, which in the long run was far more useful than simply duplicating the efforts of the United States.

Leonov’s second and final space flight took place nine years after his first, in July 1974. It was the era of Détente, and relations between the two superpowers had improved to the point that a joint spaceflight was planned. This became known in the West as the Apollo-Soyuz Test Project (ASTP) in which an Apollo and a Soyuz spacecraft would rendezvous and dock in low earth orbit. The Soyuz 19 crew comprised Leonov in command and Valeri Kubasov as flight engineer. The unnumbered Apollo spacecraft was crewed by Tom Stafford, Vance Brand, and Deke Slayton.

Both spacecraft were launched on 15 July. The rendezvous and docking took place two days later at 16:19 UTC. Three hours later, Leonov and Stafford shook hands through the open hatch of the Soyuz: it had been calculated that the handshake would take place over Bognor Regis, but delays meant that the two spacecraft were over France by the time it happened. After just under two days docked, Soyuz and Apollo parted company at 15:26 UTC on 19 July, and Soyuz landed back on Earth on 21 July. Apollo remained in space for a further three days, splashing down on 24 July. Although relations between Russia and the West have remained fractious, the Apollo-Soyuz Test Program opened up an era of cooperation in space that continues to this day.

Following his second spaceflight, Leonov became head of the cosmonaut team and oversaw crew training. He remained in this role until his retirement in 1992. He was also an accomplished artist whose works include the painting Near the Moon. On the Apollo-Soyuz Test Project, he took coloured pencils and paper with him into space, where he sketched the Earth and drew portraits of the Apollo astronauts.

Alexi Leonov is commemorated by a lunar crater to the south of the Moscow Sea on the far side of the Moon. Arthur C. Clarke’s 1982 novel 2010: Odyssey Two features a spacecraft named Cosmonaut Alexei Leonov.

Alexei Arkhipovich Leonov
Born: 30 May 1934
Listvyanka, West Siberian Krai, Russian SFSR, Soviet Union

Died: 11 October 2019 (aged 85)
Moscow, Russia

When will we go back to the Moon?

Fifty years ago today, Neil Armstrong and Buzz Aldrin became the first humans to land on the Moon. It remains one of the great moments in human history, but what happened next? At the time, as a thirteen-year-old schoolboy, I assumed that it would only be a few years before humans reached Mars. Half a century later, it sill hasn’t happened.

Six more missions to the Moon followed Apollo XI, of which only the drama of Apollo XIII and the survival of Jim Lovell and his crew made any kind of headlines. A total of twelve people – all men – walked on the Moon. Of the twelve, four are still alive including Buzz Aldrin. Neil Armstrong died in 2012 aged 82. Apollo XVII – the last lunar mission – returned to Earth on 19 December 1972, and no spacecraft carrying a crew has since left Earth orbit.

The exploration of the Solar System has been carried out purely through robot space probes. By 1969, American and Soviet probes had flown past Venus and Mars, returning data and – in the case of Mars – a few low-resolution images. Since then, space probe have reached every planet in the Solar System (including Pluto), with long-duration orbital missions of all the planets out to Saturn, and the asteroids Vesta and Ceres. There have been landings on Mars, Venus, Titan, and several asteroids and comets. There have been active rovers on Mars since 2004. At the beginning of this year, the New Horizons probe returned photographs from the distant Kuiper Belt object 2014 MU69 Ultima Thule.

But in comparison to the 1960s, human activities in space have progressed at a snail’s pace. The Russians never went to the Moon and turned their attention to space stations in low Earth orbit, which in the long term was more useful than simply duplicating the efforts of the United States. The MIR space station was in service from 1986 to 2000, and was permanently occupied between February 1990 and August 1999. There has been a permanent human presence in space in the International Space Station since November 2000.

Much of the technology of 2019 was certainly science-fiction in 1969 – computers have evolved from room-filling machines affordable only by large companies to mundane household appliances. Much of the gadgetry from the original series of Star Trek – which made its way over here from the States a fortnight before the first Moon Landing – seems quite primitive compared with present-day smartphones, iPads, and the like.

So what of crew-carrying spacecraft? The Russian Soyuz, which first flew in 1967, is still in service. The Chinese Shenzhou – currently the only other crew-carrying spacecraft in service – is based heavily on Soyuz technology. Since the retirement of the Space Shuttle in 2011, the US has been without the means to launch humans into space, and is having to thumb lifts from the Russians to the ISS. This will change when the privately operated SpaceX Dragon 2 and Boeing Starliner spacecraft come into service later this year.

To date, only the US, Russia, and China have sent humans into space, although citizens of forty countries have flown in space. India plans to launch a crew-carrying spacecraft in December 2021. No other nation currently has plans for an indigenous human spaceflight program.

American plans for an expedition to Mars have come and gone over the years. The Orion program, instigated by President George W. Bush in the wake of the Columbia disaster, has yet to fly with a crew. More recently, the Artemis program has a stated goal of returning humans to the Moon by 2024. Proposals include the Lunar Orbital Platform – a space station in lunar orbit, from which landers will take humans to the surface.

The Russians are working on similar proposals with a timescale for the 2030s and a Soyuz replacement known as Federation. Presumably this name-checks the Russian Federation (as Soyuz did the Soviet Union) rather than Star Trek’s United Federation of Planets. The Chinese are reviewing preliminary plans for a lunar expedition in the 2030s.

Ten years ago, I expressed the hope that I would live long enough to see humans land on Mars, but this is looking increasingly unlikely.

The Apollo program fulfilled President Kennedy’s goal of putting Americans on the Moon before the end of the 1960s and – no less important – before the Russians. The program was criticised because of the many problems back on Earth. Sadly, these problems have not gone away. The Cold War ended thirty years ago, but it was no more than a brief thaw in East-West relations. It is now clear that geopolitical competition rather than communism vs capitalism lies at the root of the hostility.

The international situation now – eighteen years after 9/11 – is as bad as it has been in my lifetime. Worldwide, the rise of the populist Right continues unchecked. Here in the UK, we have had almost a decade of Tory-inflicted austerity following the global financial crisis of 2008, and the last three years has been dominated by the incompetent shambles of Brexit. Yet these problems are inconsequential compared to the existential threat to humanity posed by climate change.

Nevertheless, we must not turn our backs on space. At minimum, self-sustaining colonies on Mars and the Moon would increase the chances of our survival as a species. I won’t be around in another fifty years time, but I can only hope that by the time we reach the centenary of Apollo XI the world is in a better state than it is now and humanity is firmly established as a multi-planet species.

Space suit used by Britain’s first astronaut Helen Sharman

Sheffield-born Helen Sharman was the first British astronaut and the first woman to visit the Soviet Mir space station in May 1991. The space suit she used for the mission has gone on display at the Hancock Museum in Newcastle as part of the Great Exhibition of the North.


Project Juno was a private initiative to send a Briton into space by purchasing a seat on a Soyuz mission to Mir. Helen Sharman, at the time employed by Mars as a chemist, was selected from nearly 13,000 who responded to an advertisement reading “Astronaut wanted. No experience necessary” which appeared in the British press in 1989 (other hopefuls included science fiction author Stephen Baxter).

Sharman and her backup Tim Mace underwent training at the Yuri Gagarin Cosmonaut Training Centre, Moscow (“Star City”), but the Juno consortium failed to raise the necessary funds for the mission and it faced cancellation. It eventually went ahead thanks to the personal intervention of Soviet leader Mikhail Gorbachev. However, the ambitious microgravity experiments planned for the mission had to be substituted for simpler tasks that could be performed with existing equipment on the space station.

Sharman was launched aboard Soyuz TM-12 on 18 May 1991, accompanying mission commander Anatoly Artsebarsky and engineer Sergei Krikalyov. She performed medical and agricultural tests, photographed the British Isles, and participated in a licensed amateur radio hookup with British schoolchildren. She returned aboard Soyuz TM-11 on 26 May 1991. Aged 27 years and 11 months at the time of her flight, she remains one of the youngest people ever to travel in space. The mission was one of the last to take place before the collapse of the Soviet Union.

Both Helen Sharman and Tim Mace were candidates in the 1992 and 1998 European Space Agency selection rounds for its astronaut corps, but surprisingly neither were chosen.

Helen Sharman was appointed an OBE in the 1992 Birthday Honours. She continued her scientific work and in 2015 she was appointed Operations Manager for the Department of Chemistry at Imperial College, London.


In 1965, as the space race between the United States and the Soviet Union was hotting up, officials at NASA realised that they did not have “space rated” wristwatch that could be used for the upcoming Project Gemini. Given that the program was slated to include an EVA or space walk, there was an obvious need for a watch that could withstand exposure to vacuum and other rigours of spaceflight. In addition to being able to keep good time under such conditions, the watch would have to incorporate a chronograph or stop-watch function, so astronauts could see at a glance how long they had spent outside their spacecraft and to help carry out other tasks that required accurate timing.

Rather than go through the time consuming procedure of inviting bids for a “space watch”, NASA decided to send a couple of engineers to out to downtown Houston with instructions to procure a variety of off-the-shelf chronographs for testing. The tests included exposure to extreme temperatures, vacuum, intense humidity, shock, acceleration, pressure and vibration. At the end of the tests, NASA had a clear winner as the watch most suitable for spaceflight: the Omega Speedmaster.

The Speedmaster was first introduced by in 1957 and utilised the Lemania 2310 (AKA Omega 321) manual-wind movement. It is often stated that NASA specified a manual-wind movement because they thought automatic (“self-winding”) movements would not function in zero-gravity conditions, but this is incorrect on two counts. Firstly an automatic works by inertia and is not dependent on gravity; secondly the simple reason NASA selected a manual-wind chronograph is that at the time that was the only type available. The first automatic chronograph movement – the Zenith el Primero – did not come into use until near the end of the decade. However it is likely that in the cramped conditions of a Gemini or Apollo spacecraft, there would be insufficient activity to keep an automatic fully wound and a manual-wind would be more suitable.

On 3 June 1965, Gemini 4 pilot Edward White became the first US astronaut to make a spacewalk. He was wearing an Omega Speedmaster, strapped to the outside of his spacesuit with a Velcro strap. Curiously it was not until almost a year later that Omega finally learned the use to which NASA had been putting their watches. As might be expected, they wasted little time in cashing in and photographs of White’s spacewalk were soon featuring in their advertising literature. The watch itself was renamed the Speedmaster Professional, but its finest hour was yet to come.

Early on the morning of 21 July 1969, Buzz Aldrin stepped out onto the surface of the Moon wearing a Speedmaster Professional, which thus became the first watch to be worn on the Moon. Earlier, Neil Armstrong had had to leave his own watch in the Eagle lunar module after the lander’s onboard chronometer developed a malfunction. Sadly this historic watch was later stolen while on loan to the Smithsonian and has never been recovered.

In April the following year a Speedmaster Professional was used to time a crucial engine burn aboard the crippled Apollo XIII during the desperate and ultimately successful endeavour to return the spacecraft safely to Earth.

Meanwhile feeling was growing that an American watch should be used on NASA moon missions and the US-owned Bulova company lobbied the White House for their watches to be used instead of the “Speedy Pro”. Eventually NASA was persuaded to test a fresh batch of watches, including a specially-manufactured Bulova chronograph, but the Omega again came out on top with the Bulova stopping several times during testing.

By now, not only NASA was equipping its astronauts with the Speedmaster Professional. In 1975, when an Apollo spacecraft rendezvoused with a Soviet Soyuz in Earth orbit, both crews were wearing what had by now become known as the Moonwatch.

In 1978 NASA held a fresh series of tests ahead of the Space Shuttle program. Once again the Speedmaster Professional triumphed. The watch had by now received an updated movement, the Lemania 1873 (AKA Omega 861), which featured a shuttle/cam system rather than a column-wheel. The former design is simpler and thus is cheaper to both manufacture and service, but it yields nothing in terms of performance and reliability. The 1873 is again a manual-wind movement.

Externally however the Speedmaster Professional has changed very little in over half a century, even retaining its old-fashioned Hessalite (plexiglass) crystal in preference to a modern scratch-resistant sapphire crystal. This has been at the request of NASA. Plexiglass scratches quite easily, but it is virtually indestructible. By contrast, a sharp blow can shatter a sapphire crystal. Having sapphire fragments floating about inside the zero-g environment of a spacecraft is obviously not a good idea! A sapphire version, also featuring a sapphire display back, is available at extra cost but many enthusiasts prefer the Hessalite model, which is the only flight-qualified version.

The Speedy Pro is certainly not the only watch to go into space (and was probably not even the only watch worn on the Moon – contra Omega’s website), but even now it is the only watch permitted to be used for EVAs from the International Space Station or from the Space Shuttle. The Casio G-Shock – a watch almost as iconic as the Speedy – is routinely worn aboard the ISS, but because their batteries may explode in a vacuum, they cannot be used for spacewalking.

Who knows, the Omega Speedmaster Professional may even eventually become known as the Marswatch.

© Christopher Seddon 2009

Everything you wanted to know about the Moon

Most people will think nothing of the Moon should they happen to see it in the sky. This is hardly surprising, the Moon is after all one of only two distinct, instantly recognisable objects (the other being the Sun) that we are guaranteed to see (even here in Britain!) during our lifetime; there can be nobody alive who has not known of it from their earliest childhood. The Moon is a ubiquitous part of our culture and almost certainly has been since earliest times. Its beauty in the night skies has inspired writers, poets and artists for centuries. Reaching for the Moon was once synonymous with desiring the impossible – until man reached it. Even now, almost four decades on from Armstrong’s momentous giant leap for mankind, the Moon remains the only astronomical body other than Earth to be visited by humans.

What’s in a name?

Many people think the “official” name of the moon is the Latin form Luna, but in common with Terra (Earth) and Sol (the Sun) the term Luna has no official standing and is rarely encountered outside of science-fiction novels, though the adjectival forms “lunar”, “terrestrial” and “solar” are in common usage. The “official” name for the Moon is – the Moon (capitalised)! The uncapitalised form – “moon” – is a generic term for any natural satellite of any planet, including our own. Some prefer this term over “satellite” thinking the latter implies something manmade. Strictly speaking a manmade satellite should be referred to as an “artificial satellite” but this usage is now very rare.

The phases of the Moon

The most obvious thing about the Moon is that its appearance changes from night to night. The Moon is not the only body visible from Earth to exhibit phases – Venus and Mercury do also – but without a telescope those of Venus are very difficult to see and those of Mercury are way beyond human perception. The explanation for the phase is straightforward; only one hemisphere of the Moon is illuminated by the Sun at any one time (in common with all other non-luminous solar system objects) and the portion of the illuminated hemisphere visible from Earth changes as the Moon travels round the Earth on its orbit. When the Moon and Sun are on opposite sides of the Earth a full moon is seen; when they are on the same side the Moon disappears altogether. When they are 90 degrees apart a half moon is seen.

The time taken for the Moon to cycle through its phases (the synodic month, defined as the time taken for the Moon to return to the same position relative to both Earth and Sun) is actually longer than the time taken for it to complete a single orbit (the sidereal month) – 29.53 days on average, as opposed to 27.32 days. The reason for this is while the Moon is completing an orbit of the Earth, the latter is moving on its own orbit around the Sun, and the Moon has to move slightly further before it can return to the same position relative to both Earth and Sun.

The wrong time of the month

In 1972 the American researcher Alexander Marshack claimed that people were making records of the phases of the Moon 30,000 years ago. After extensive research that entailed examining just about every prehistoric artefact he could lay his hands on for calendrical notches, he published his findings in a book entitled The Roots of Civilization. Marshack claimed that the tallies corresponded to lunar months. On the face of it, this seems highly plausible. It is now generally accepted that the people of that era were every bit as mentally capable as we are today, and there is little doubt that they would have been aware that the phase of the Moon changes from night to night in a predictable manner. But there are two problems – firstly, it seems unnecessary to record, say, the days since the last full moon when one can simply look at the Moon, note the current phase, and work forward to when the next full moon will occur. The second problem is the tallies vary in numbers of days by more than can be explained by the small seasonal variations in the length of the lunar cycle, or by observational error. However there is another cycle with an average length almost identical to the lunar cycle that does show a certain amount of variation – the human menstrual cycle. It is my guess that this is what was being recorded, since the advantages of knowing when that time of the month is approaching are fairly obvious, and this was probably also the case 30,000 years ago!

That the menstrual cycle is almost exactly one lunar month in duration is now thought to be pure co-incidence, but it is one that was noticed many thousand years ago. The words “moon”, “month”, “menstruate” and “measure” (time) all have the same Proto-Indo-European root. The proto-Indo-European language is the hypothetical common ancestor of the Indo-European languages, which include Latin, Greek, Sanskrit and the modern languages derived from them. According to one popular theory, the Proto-Indo-Europeans were warlike nomads who originally expanded from the Eurasian steppes at around 4000 BC, taking their language with them. A rival theory, proposed in the mid-1980s, claims that Proto-Indo-European origins go even further back, and that they were originally farmers living in Asia Minor, shortly after the end of the last Ice Age. Regardless of which theory is correct (I personally favour the farming theory), the origin of the word “moon” is very ancient indeed.

The Moon from an astronomical viewpoint

The Moon is ranked as a satellite of the Earth. Most of us will be aware that the Earth is in astronomical terms quite undistinguished, and that the same goes for the Sun. Even though the Milky Way, of which the Sun is a part, is classed as a large galaxy one doesn’t have to look far (in fact a mere two million light years) to find a larger galaxy (the Andromeda Galaxy). In a way this is exactly what we should expect from the Copernican Principle or Principle of Mediocrity, an important principle in the philosophy of science which states that Earth holds no special place in the universe and that humans are not privileged observers. Right, so this presumably means that the Moon is equally average? Well, actually, no.

The Moon is a remarkable object and as far as the Solar System is concerned, it is unique. The Moon is a fully paid-up member of the Solar System’s “Big Seven” group of satellites, all of which are larger than Pluto and Eris (the two smallest planets(or largest “dwarf planets” if you insist)). The Moon is by no means the largest member of this group, but all the other six are satellites of giant planets: the Earth is at best only medium-sized. Indeed many astronomers take the view that the Moon is too large in relation to the Earth to be considered a mere satellite and elevate it to the rank of a sister world, classifying the Earth-Moon system as a binary planet. However this view is not really valid. Large though the Moon is, it is still only 1/81 the mass of the Earth; the centre of mass for the Earth/Moon system lies below the surface of the Earth and the Moon cannot be classed as anything other than a satellite of Earth.

Lunar geography – or Selenography

Though most will know what it means, terms like “lunar geography” , “lunar geology”, etc, are oxymorons as the prefix “geo-“ means pertaining to the Earth. The correct terms are “selenography”, “selenology”, etc; the prefix “seleno-“comes from Selene, the Greek goddess of the Moon.

It is not true, as is often believed, that Galileo was the first to map the Moon using a telescope. That distinction must go to Thomas Harriot in 1609, a year before Galileo. However, both men clearly observed mountains, valleys, craters and comparatively smooth areas known as maria or seas. It was at one time believed that these latter features actually were seas, or at least dried-up sea beds, but we now know from samples brought back from the Moon that they have never contained any water.

However, in 1998, it was widely reported that NASA’s Lunar Prospector probe had found water on the Moon, allegedly from comets that had landed in polar regions permanently hidden from the Sun and thus remained frozen. In fact, the probe had only detected evidence of hydrogen on the Moon’s surface. While this could be due to water, I have to say I am highly dubious. Any comet impacting the Moon would almost certainly do so at a relative velocity high enough to vaporise it instantly as its kinetic energy is transformed into heat.

Another theory, popular before the Space Age, was that the maria were great dust-bowls, and any spacecraft landing there would be swallowed up. The idea was featured in two vintage novels by Sir Arthur C. Clarke, Earthlight and A Fall of Moondust, the latter telling the story of a “dust cruiser” designed to “sail” the lunar “seas”.

Today we know that the maria are large dark plains of basalt, formed by volcanic activity billions of years ago.

The origin of the lunar craters has been the subject of considerable controversy over the years. It was once believed that they were volcanic in origin, similar to calderas, but it is now generally accepted that they are the result of meteoric impacts. It was however quite a long time before the volcanic theory was abandoned and a number of astronomers, including Sir Patrick Moore, continued to argue for it until as late as the 1990s.

A Canterbury Tale

Assuming that the impact theory is correct could any new craters have appeared in historic times? In theory, there is no reason why not, though in practice it seems unlikely with impacts forming craters visible from Earth being fairly rare events. However in the 1970s an American astronomer named Jack Hartung claimed that a report made on 18 June 1178 by a Canterbury monk named Gervase could be interpreted as an eye-witness account of the formation of the crater Giordano Bruno.

… after sunset when the moon had first become visible a marvellous phenomenon was witnessed by some five or more men who were sitting there facing the moon. Now there was a bright new moon, and as usual in that phase its horns were tilted toward the east; and suddenly the upper horn split in two. From the midpoint of this division a flaming torch sprang up, spewing out, over a considerable distance, fire, hot coals, and sparks. Meanwhile the body of the moon which was below writhed, as it were, in anxiety, and, to put it in the words of those who reported it to me and saw it with their own eyes, the moon throbbed like a wounded snake. Afterwards, it returned to its proper state. This phenomenon was repeated a dozen times or more, the flame assuming various twisting shapes at random and then returning to normal. Then after these transformations the moon from horn to horn, that is along its whole length, took on a blackish appearance.

It has been suggested that Gervaise saw a meteorite impact, and that the crater Giordano Bruno (named for the Italian philosopher who was burned at the stake for heresy in 1600) was formed as a result. Proponents of this idea point out that the time of the year is consistent with an impact from the so-called Taurid Complex, associated with Enke’s Comet, but the whole thing really has to be taken with a king-sized pinch of salt. Surely a small group of men in Canterbury would not have been the only people in the whole world to see and note such a major disturbance in the natural order of things? A more recent mathematical treatment of the theory showed that Earth would have been bombarded with ejecta from the impact. This would have resulted in spectacular meteor showers of roughly 50,000 meteors an hour being visible all over the world for a week – yet there is absolutely no record of anything of the sort being seen.

Crucially, the Moon was close to the horizon at the time and what Gervaise reported was almost certainly an unusual cloud phenomenon or atmospheric disturbance.

The Moon in fiction

What is arguably the world’s first ever work of science-fiction, entitled A True Story, was written by the Greek satirist Lucian of Samosata in the 2nd Century A.D. and dealt with imaginary voyages to the Moon, but the topic did not become popular until the invention of the telescope in the 17th Century. Authors who wrote about journeys to the Moon included Johannes Kepler, Francis Godwin and Cyrano de Bergerac though the heroes tended to travel by unlikely means such as harnessing a flock of geese.

About a hundred years before Project Apollo, Jules Verne described an American moon program in which a projectile is launched from a space gun in Florida and splashes down in the Pacific, just as Apollo would later do. Some 35 years later, H.G. Wells sent his characters to the Moon in a vehicle utilising anti-gravity – much to the disgust of the by then elderly Verne. This criticism evidently affected Wells, who much later used a space gun himself in the moon shot sequence at the end of the movie Things to Come.

The Moon featured in innumerable works by the 20th Century’s “Holy Trinity” of Sir Arthur C. Clarke, Isaac Asimov and Robert Heinlein.

Inevitably the Moon has featured in many science fiction movies and television series, with manned moonbases being a popular theme for the latter. Gerry Anderson, best known for his classic puppet shows such as Thunderbirds, made two live-action series featuring moonbases. In the first, UFO, interceptors were launched from a moonbase to destroy hostile alien spacecraft. The second, Space 1999, was an altogether more ambitious affair. It was billed as a British answer to Star Trek but despite a huge budget, excellent special effects and a star cast that included Martin Landau, Barbara Baines, Barry Morse, Catherine Schell, Joan Collins, Brian Blessed and Judy Geeson, the series was not a success and was cancelled mid-way through its second run. The main problem was an utterly implausible plot device in which a nuclear explosion sent the Moon careering off into outer space at what one must presume was many times the speed of light (a physical impossibility in itself), given that most weeks would find it hurtling towards a new planetary system. Hopes would rise among those marooned on Moonbase Alpha that the new system would contain an inhabitable world on which they could settle, but on the occasions that it did something would always prevent colonisation, be it paranoid aliens fearing cultural contamination by “primitive” humans (this one cropped up on several occasions); an interplanetary battle of the sexes (a group of rather butch-looking women hijacked Alpha and used it as a platform to lob nuclear missiles at the men, who had already been banished to another planet for being “unreasonable”); a time-warp that reverted the crew to cavemen (this provided an excuse to put the lovely Zienia Merton in a leopard-skin), or the putative new home turning out to be rather inconveniently composed of antimatter. Even when the Moon was in interstellar space things were rarely quiet: black holes and time warps were as frequent as tailbacks on the M25; other menaces included a space brain, a monster dwelling in a Sargasso Sea of abandoned spaceships and miscellaneous aliens in suspended animation, who invariably turned out to be bad guys sent into exile by their peace-loving compatriots.

Is the Moon Earth’s only natural satellite?

Could the Earth have a second, undetected satellite? On the face of it, there is absolutely no reason why not. Jupiter is now known to have at least 63 satellites; Saturn has about the same number; and even Pluto has three. However if a second Earth satellite were to exist, it would have to be very small indeed to avoid detection. It is not often appreciated that were the Moon only two miles in diameter, it would still be visible to the naked eye.

Nevertheless, the idea that the Moon might not be our planet’s sole attendant has intrigued astronomers for the better part of two hundred years. In 1846 Frederic Petit, Director of the Toulouse Observatory, claimed that a second Earth satellite had indeed been discovered. Petit’s claim was soon refuted, but he became obsessed with the idea of a second satellite. Fifteen years later, he published an abstract in which he proposed the existence of a second satellite to account for then-unexplained anomalies in the Moon’s orbit. The theory attracted little interest among astronomers, and doubtless would have been entirely forgotten by now had a young French writer by the name of Jules Verne not read the abstract and immortalised Petit and his satellite in the novel From the Earth to the Moon, in which the Petit object passes close to the space travellers projectile, pulling it off course and swinging it into an orbit around the Moon.

The idea of a second moon was revived several times during the last century, and shortly after the end of the Second World War, Clyde Tombaugh, discoverer of Pluto, carried out a most comprehensive search. He used equipment so sensitive that it would have shown a lump of coal the size of a football a thousand miles away. He failed to find anything.

It is now believed that the combined gravitational effects of the Earth, Moon and Sun would rapidly eject any small satellite from Earth’s orbit, ruling out the existence of a second moon. Nevertheless in 2002 an object known as J002E3 was discovered in Earth orbit – but it was soon discovered to be almost certainly the discarded third-stage booster from the Apollo XII mission in November 1969. It is believed that the object left orbit in June 2003 and may return around 2032.

It is sometimes claimed that the asteroid 3753 Cruithne ranks as a second Earth satellite. Discovered in 1986, Cruithne has an unusual orbit, known as a “horse-shoe” orbit, due to the influence of Earth. However it is in orbit around the Sun, not the Earth and therefore it is not an Earth satellite.

A Cosmic Coincidence

One of the most singular features of the Moon is the fact that it appears almost exactly the same size as the Sun in the sky. The reason for this is that while the Sun is 400 times the diameter of the moon, it is also 400 times further away, so both objects appear the same size when viewed from Earth. This is a pure co-incidence, but it is responsible for what is surely one of the most spectacular phenomena to be seen anywhere in the Solar System – a total eclipse of the Sun. A solar eclipse is, of course, due to the Moon passing directly between the Sun and the Earth, casting its shadow upon the latter (strictly speaking, the phenomenon is an occultation, not an eclipse). Because the Moon’s disc is just sufficient to hide that of the Sun, the latter’s atmosphere, the so-called corona can be seen in all its splendour. In fact it is a close call and for a total eclipse to occur, the Moon must be close to perigee (i.e. its minimum distance from Earth). Otherwise, a thin ring of the Sun’s disc is left showing, quite enough to drown out the glorious corona, and the eclipse is said to be annular. Because the Moon’s orbit is inclined at five degrees, an eclipse does not occur every month, though at least two must occur in a given year. However this figure includes partial eclipses, when the Moon does not pass directly in front of the Sun. Even when a total eclipse does occur, the area experiencing totality is only a small corridor, though it may extend for thousands of miles as the Moon’s shadow races across the Earth’s surface.

I have only witnessed one total eclipse of the Sun, that being the one in Cornwall in August 1999. Although cloudy skies prevented me from seeing totality, it was still an awesome experience as day became night in a matter of seconds. Sea birds, believing night really had fallen, hooted in great excitement. On the horizon was seen a band of orange light, marking the limits of totality. The scene was one of great beauty and although it was disappointing to have missed something I had been waiting to see since my childhood, it was still a worthwhile experience.

We will not always be able to enjoy the spectacle of a solar eclipse, because tidal effects are causing the Moon to recede from the Earth by 3.8 centimetres per year. That might not seem like a lot, but it adds up. When the first maps of the Moon were being drawn up, three centuries ago, the Moon was 11.4 metres (just under 40 feet) closer to the Earth. When modern humans first reached Australia, 50,000 years ago, the Moon was 1900 metres (rather more than a mile) closer; when the dinosaurs became extinct 65 million years ago, it was 2470 kilometres closer.

Eventually it will be too far away for its disc to fully block out the Sun, even at perigee. These effects are also causing the Earth’s spin to slow and the day is gradually lengthening. Again, these effects are small but they add up over time and account for discrepancies amounting to several hours in the timing of eclipses observed in antiquity.

The Dark Side of the Moon

As is correctly pointed out in the eponymous Pink Floyd album, there is no “dark” side of the Moon: each part of the Moon experiences as much daylight as it does night time. So where does the idea that the Moon has a “dark” side come from? In common with almost all bodies circling a larger primary, the Moon exhibits so-called “captured rotation”, meaning that it turns on its axis exactly once in each circuit of its primary. In other words, a lunar day is exactly a month long. It is often said that this results in half the Moon’s surface being permanently hidden from view on Earth, leading to the misconception that the hidden side is in permanent darkness. If this were true, we’d see a full moon all the month round! The phase is of course due the part of the Earth-facing side being in darkness. In fact it is not strictly true that only half of the Moon’s surface can be seen from Earth. Because the Moon (in common with all other objects in the Solar System) does not move in a perfectly circular orbit, its orbital velocity varies slightly during the course of a month in accordance with Kepler’s Laws of Planetary Motion. This means that the orbital motion and axial spin are at times slightly out of step, and in consequence we can see portions of the “hidden” side. Because the Moon’s orbit is inclined at five degrees to that of Earth, we can also see alternately beyond the north and south lunar poles. Finally, parallax effects result in observers being presented with slightly different portions of the Moon’s surface at different times of the day and in total, about 59 percent of the Moon’s surface may be observed from Earth at various times.

Origin of the Moon

As one might expect, the origin of the Moon has been the subject of many theories over the years. The first theory to gain widespread acceptance was put forward by Sir George Darwin (son of Charles). Darwin suggested that the Earth and Moon had originally formed a single rapidly rotating, molten mass. The tidal forces raised by the Sun and the centripetal forces of its own motion caused it to become pear-shaped and eventually split into two objects of unequal size. A strong supporter of the fission theory was the American astronomer W.H. Pickering, who suggested that the scar left by the Moon’s breakaway was now the basin of the Pacific Ocean.
Unfortunately the theory was pear-shaped in more ways than one. A mathematical treatment of the dynamics involved showed that it was unsound and it had to be abandoned. This did not prevent it from being used as the basis of an ingenious science fiction movie, Crack in the World, in which an attempt to tap energy from the Earth’s molten core goes disastrously awry and triggers a series of earthquakes. A growing rupture in the Earth’s crust threatens to tear the planet apart and rival scientists Stephen Sorenson (Dana Andrews) and Ted Rampion (Kieron Moore) are forced to put aside their differences and try to come up with a solution. An attempt to avert disaster by exploding a hydrogen bomb in the shaft of an active volcano is only partially successful, and a whole portion of the Earth is blasted away into space, where it forms a new satellite. The movie’s closing reel shows the Moon and its new sibling in the sky together, the whole process having been observed from no more than a few hundred yards by Rampion – accompanied, of course, by the movie’s love-interest (Janette Scott).

The next theory to be put forward suggested that the Moon was originally an independent body, but it wandered too close to the Earth and was captured. There is little doubt that this has happened elsewhere in the Solar System, Mars’s dwarf attendants and several satellites of the giant outer worlds, including Neptune’s major satellite Triton – only slightly smaller than the Moon – were almost certainly captured from independent orbits. The theory was popular for a time and in the middle part of the last century an Austrian researcher named H.S. Bellamy even suggested that it might have happened fairly recently (needless to say, this accounts for the destruction of Atlantis). But captures that are believed to have occurred all involve objects that are very small in relation to their captors, and as we have observed, the Moon is fairly large in relation to the Earth.

Another theory states that the Moon simply formed in Earth’s orbit from the same primordial material, but this model fails to explain why the Moon is less dense and deficient in iron in comparison to Earth.

The currently popular theory, put forward by American scientists W.K. Hartmann and D.R. Davis in 1974, proposes that an object about the size of Mars collided with Earth, and while the bulk of its mass including its iron core merged with the Earth, enough debris was ejected into space from Earth’s mantle to form the Moon. The theory explains why the Moon is rather less dense than the Earth, as denser materials were not blasted into space by the impact. The theory is not without its problems, but seems to be the most plausible explanation put forward to date.

From the Earth to the Moon

As we have seen, some 59 percent of the Moon’s surface can be seen under various conditions from Earth. Not until the dawn of the space age was anything definite learned about the remaining 41 percent. In October 1959, the Soviet probe Lunik III made a fly-by of the far side of the Moon. Because the probe was out of radio contact with Earth as it passed behind the Moon’s far side, the pictures it took could not be simply beamed back to Earth. Accordingly, film was automatically exposed and developed. As the probe emerged from behind the Moon, the developed film was imaged by a TV camera and the first blurry images of the Moon’s hidden side were transmitted back to Earth. It sounds crude, and by today’s standards it was, but it was a tremendous technical feat for the time.

As the Cold War ratcheted up tensions between East and West, so the Soviets continued to score an impressive succession of “firsts” in space, but the US was galvanised into a response and on 25 May 1961 President John F. Kennedy threw down his historic challenge:

I believe that this nation should commit itself to achieving the goal, before this decade is out, of landing a man on the Moon and returning him safely to Earth. No single space project in this period will be more impressive to mankind, or more important for the long-range exploration of space; and none will be so difficult or expensive to accomplish.

In May 1961, Alan Shepard had only just become the first American to fly in space, yet little over nine years later after the flight of Lunik III, men saw the Moon’s hidden side with their own eyes as Apollo VIII made its historic circumnavigation of the Moon at Christmas 1968. Seven months later Armstrong and Aldrin became the first men to actually land there, realising Kennedy’s goal with less than six months to spare. The technological leap that made this possible might sound incredible, but it must be remembered that even the technology of Project Apollo was quite primitive by today’s standards. It is a fact that the Eagle’s on-board computer was actually far less powerful than that of a modern-day mobile phone! (I refuse to comment on conspiracy theories that the Moon landings were faked because it is patently obvious that the idea is absurd.)

At all events, the US won the race to the Moon. Not until much later did it emerge that early Soviet successes owed more to the genius of Chief Designer Sergei Korolev than to any superiority of communism over capitalism. But Korolev’s health had been ruined by a spell in the gulag during Stalin’s reign of terror and he died in 1966 during a botched operation to remove a tumour. With his death ended any hopes of perfecting the N1 booster with which he had hoped to put a man on the Moon. The race to the Moon lost, the Soviets turned their attention to establishing a near-permanent human presence in Earth orbit – which in the long run was of far more benefit than simply duplicating the efforts of the US.

When will people go back to the Moon? In 1972, when Cernan and Schmitt blasted off from the Moon’s surface, it was said that nobody would be going back in the 20th Century. I did not believe this (I assumed that men would be on Mars before the century was out), but the public’s attention-span is short and after the Moon landing had been made, only the astonishing drama of Apollo XIII made the headlines (and, a quarter of a century later, an excellent if not entirely accurate Hollywood movie). NASA turned its attention to the Space Shuttle, setting back the manned exploration of space by decades. As an experimental proof-of-concept spaceship, there is no doubt that the Shuttle was a technological triumph. As a practical manned reusable heavy-lift system however it has been an unmitigated disaster that cost the lives of the crews of Challenger and Columbia. It was the latter tragedy that prompted President George W. Bush, in one of the very few highlights of his presidency, to announce what has since become known as Project Constellation, which will return humans to the Moon, and on to Mars – using designs that draw heavily from Project Apollo, albeit using hardware developed originally for the Shuttle.

A permanently inhabited base on the Moon should be established no later than the middle part of this century. When it is, one of science fiction’s oldest and most central themes will be a reality at last.

© Christopher Seddon 2007