The written history of the human experience of observing the solar system goes back a long way. David C. Lindberg, in The Beginnings of Western Science states that "some of our oldest written records, going back more than 4000 years, are astronomical in character." The unwritten history goes back to time immemorial, when emerging humankind looked up in wonder at the beauty of a full moon, or cowered from the sight of a myriad of falling stars. Meteors and comets have always been harbingers of doom in common folklore, scaring prey and, later, blighting the harvest. Mass events such as the seasonal appearance of the Leonids, Taurids and Perseid meteor showers must have been both awesome and terrifying. The 1910 appearance of Halley's Comet sent the world's doomsayers into overdrive (perhaps even the 1986 appearance as well)! Its appearance in the skies over England in 1066 seemed to presage the coming of the Normans, as its image was incorporated into the Bayeux Tapestry. There is also some speculation concerning the Serpent Mound in Adams County, Ohio, having been erected as a consequence of the Comet's appearance, as archaeological dating in the 1990s seemed to indicate that the Mound was built around 1075 AD.
Eclipses of the sun and moon have also had an ominous connotation throughout history. Andrew D White, in his classic Warfare of Science with Theology, has this to say on the subject: "Out of the ancient world had come a mass of beliefs regarding comets, meteors and eclipses; all of these were held to be signs displayed from Heaven for the warning of mankind...Eclipses were...supposed to express the distress of Nature at earthly calamities..." Thucydides, writing on the Peloponnesian War, suggests the same - "wide areas...were affected by violent earthquakes; there were more frequent eclipses of the sun than had ever been recorded before; in various parts of the country there were extensive droughts followed by famine; and there was the plague which did more harm and destroyed more life than almost any other single factor." Historical eclipses augured auspicious occasions, among them the births of Romulus, founder of Rome, and Mohammad, founder of Islam, and the deaths of Julius Caesar, Herod, Augustus, Agrippina and Jesus. The Old Testament (Amos Ch 8, v 9) states that, on a day collated to be June 15, 763 B.C, God warns He "will make the Sun go down at noon, and darken the Earth in broad daylight." - an event that is chronologically verified by an Assyrian document called the Eponym Canon.
In 1868, two Englishmen discovered the previously unknown element Helium during an eclipse as King Mongkut of Siam (the same ruler featured in Anna Leonownes' The King and I) watched the same event, which he himself had predicted. Mongkut was something of a Renaissance man and had hoped to prove to his people that the advent of an eclipse was nothing to fear. The locals, however, persisted in their habit of banging gongs and lighting firecrackers to ward off the evil eclipse demon Rahu. It is now known that solar flares can indeed have a marked impact on terrestrial weather. The withdrawal of the Sun's beneficence, even for a short time, would have brought terror to a pre-scientific community, and the accompanying disruptions of weather a few days later would not have gone unnoticed.
Similarly, the eclipsing of the moon was seen as an omen. A fortuitous lunar eclipse helped quell a mutiny among the Roman legions following the death of Augustus in 14 AD. On February 29, 1504, Christopher Columbus duped the natives of Santa Gloria, Jamaica, into providing him with supplies by telling them that God would show his displeasure at their lack of charity by taking away their moon, an event predicted in the Calendarium, a copy of which Columbus had aboard ship. There has always been a deep distrust amongst all human populations for anything originating in the stars which, of course, symbolise the ultimate unknown. Newly regurgitated theories of panspermia, that is, life on Earth being seeded from star matter via meteors, comets and asteroids, notwithstanding, gazing into the heavens gives us a sense of vulnerability and insignificance.
In Taurus lies the Crab Nebula, a rapidly expanding cloud of gas, the remnants of a star that did indeed explode, going supernova in 3000 BC. The explosion was seen and recorded by Chinese astronomers in 1054 AD, as the light from the original supernova took some 4000 years to reach us. What they made of the sight is not reported, but the nova was bright enough to be seen quite plainly in the full light of day. The observations of early Chinese astronomers have proven an indispensable resource to modern astronomers. In all probability, the star of Bethlehem was also a supernova event, as Chinese astronomers recorded a new star in the constellation Capricorn in March and April of 5AD, which was visible for 70 days or so. A supernova was witnessed by Danish astronomer Tycho Brahe in 1572 in the constellation of Cassiopeia, which has since become known as Tycho's Nova. This aristocratic Dane was known as an eminent astrologer as well as a brilliant astronomer, and compiled a list of 'Tykobrahe Days', dates which, in the common folklore of the day, were thought to be especially unlucky. Prominent astronomer Johannes Kepler studied a naked eye supernova in 1604, shortly before the discovery of the telescope.
Another manifestation of ancient examinations of the sky is the astrological zodiac, originating from an awareness that the planets always lie within a few degrees of the ecliptic, the plane of the Earth's orbit around the Sun. The stars within this narrow band were separated into twelve groups, the signs of the zodiac. The planets' positions within these signs were then scrutinized, as two of the seven visible planets (i.e. Sun, Moon, Mercury, Venus, Mars, Jupiter and Saturn) have an obvious direct influence on our species, as the Sun is fundamental to us, and the Moon divides the year into months, controls the tides and so forth. It was therefore assumed that the other planets would also affect the lives of humankind, albeit more subtly. Saturn, the slowest planet, is associated with laziness; Jupiter, bright and high in the night sky, is correlated with ambition; Mars has always been a harbinger of war; Venus, the morning or evening star, is linked to love and lust; Mercury, hard to see and fast-moving, has an association with thievery and/or quick-wittedness.
The majority of stars within the zodiac retain the names that link them to their constellations - Deneb in Leo is shortened from 'Denobola', which means 'the lion's tail' in Arabic, a guide to the exact location of the star. However, most of the appellations attached to constellations come from rather more archaic explanations. The Dog Star, Sirius in Canis Major, defers to the ancient Egyptians who regarded the Milky Way as a celestial reflection of the Nile. When Sirius rose just before the sun preceding the great life-giving flood of the Nile, shepherds had but a few days to move their flocks to higher ground. Thus the rising of Sirius (and Procyon at that time) called the dogs to work. Both stars were known as the Dog Stars to the ancients. Similarly, the modern constellation of Aquarius has nothing to do with an imaginary water carrier, but represented the constellation in heliacal rising as the rainy season arrived. Cancer also was not an image of a crab in the sky, but rose when the crabs climbed out of the Nile.
The telescope was first described in October of 1608 and first used in astronomy in July of 1609. Within a year, controversy had erupted about who invented the new instrument and who had made the first viable astronomical observations with it. Largely through the speed in which he published his landmark pamphlet Sidereus Nuncius, The Starry Messenger, Galileo Galilei is usually considered the winner, at least in the observation stakes. Galileo first saw the four largest moons of Jupiter, made out the topography of the moon and got to witness a multitude of never-before-seen stars. His discovery of Jupiter's moons went diametrically against the then-accepted picture of the universe, which required *everything* to go around the Earth. It did fit, however, with Copernicus' theory, which stated that the Earth, and all the other planets, went around the Sun. In 1610, Galileo's studies of the planet Venus sent a further death-knell through the Earth-centred view of the cosmos. If Venus exhibited phases, just as our Moon does, it meant that, at times, Earth and Venus were on opposite sides of the Sun, and at these times Venus could be seen with more than half the planet illuminated, like an almost full Moon in miniature.
Johannes Kepler was granted Tycho Brahe's data upon the death of the latter, which he used in the formulation of his famous laws of planetary motion. Kepler was a religious man, a devout Lutheran, which complicated his life inasmuch as he often found himself caught up in the socio-religious upheaval of his age. However, he was not conflicted about his work, which he equated with a Christian duty to disseminate the works of God. He followed the general perception of the time stating that God had made the Universe according to a mathematical plan. All his insights were structured thus, which can be seen as something of an irony when it is considered that the accuracy of his astronomical tables did much to prove the truth of the heliocentric view of the Solar System, in direct opposition to Christian dogma of the time.
Almost two centuries passed before a planet was discovered however, by William Herschel in 1781. This was the first time in recorded history that a new planet had been found, as Uranus' orbit is almost twice as far from the Sun as Saturn. Half a century after that, in 1845, a Frenchman, Urbain Le Verrier, used Newton's 150-year-old Laws of Motion to predict the existence of a planet that interfered with the orbit of Uranus. Consequently, Neptune was discovered.
The existence of Planet 'X', the ninth planet, was long suspected by Percival Lowell, more well-known for his famously debunked theory of canals on Mars. These canals had first been seen by an Italian astronomer, Giovanni Schaiparelli, in 1877, when the planet was closer to Earth than usual. Schaiparelli found the planet's dark areas to be joined by narrow lines, and these lines appeared to be relatively straight. Lowell, however, misinterpreted Schaiparelli's word 'canali', which in the original Italian means 'channels', i.e. naturally occurring river channels, to mean literally 'artifically created canals'. He established his observatory in Flagstaff, Arizona for the express purpose of observing these canals, which he concluded were built by Martians to supply water from the polar caps to the rest of the planet. This led to the popular notion that Mars was inhabited, and on to many great works of science fiction! Lowell also searched for the elusive Planet X, however his computations yielded nothing and he died disappointed in 1916. Yet, for all that his own search failed, he did unknowingly photograph Pluto on two occasions. In 1930 a former lab assistant of Lowell's, Clyde Tombaugh, found the planet during a systematic sweep of the zodiac based on Lowell's calculations.
The various planetary satellites have been discovered over a similar time-frame, up to and including various NASA missions around the planets, the most famous of which are the Pioneers and Voyager. Neith was the name of a speculated moon of Venus. In 1887 the Belgian Academy of Sciences published a short tome in which every purported sighting of this moon was investigated in detail. All could be explained away by erroneous viewings of various stars. However, in 1892 E. E. Barnard recorded a seventh magnitude object near Venus. There is no star in the position that Barnard reported and, such was his reputation, the sighting has never been conclusively explained. More promise was accorded to Vulcan (not Mr Spock's planet!), apparently orbiting between Mercury and the sun. Researchers had discovered a peculiarity in Mercury's orbital motion and the explanation they deduced was the presence of an unseen planet. Yet, with the confirmation of Einsteins's theory of relativity in the 1930s, Vulcan too was consigned to fiction.
It is supposition concerning a second moon for our own planet that may well be proved correct. Dr Paul Wiegert et al, in their paper Meteoritics and Planetary Science say that the asteroid 2002 AA20 "will allow transition to a quasi-satellite state" in about 600 years time, as its horseshoe-like orbit brings it comparatively near the Earth. The vast majority of asteroids, some co-orbital with planets, are in the Kuiper Belt, following Mars' or Jupiter's orbits. 2002 AA20 is the first one known for Earth. Its round but slightly tilted orbit makes it an easy body to reach with a spacecraft and even to conceivably become a source of raw materials for us in the future.
Asteroids have now captured the imagination of the public, with several recently coming relatively close to our planet. The latest, Asteroid 2007 TU24, passed within 538,000 kilometres, about 1.4 times the distance between the Earth and the moon. At 600m in length, it was big enough to provoke catastrophic damage had it hit the Earth’s surface but, say s Steve Ostro, a senior astronomer at NASA’s Jet Propulsion Laboratory, 2007 TU24 “was the closest until at least the end of the next century.”
Some 300 Earth-crossing asteroids have already been discovered, but the total number is estimated at 1500 or more objects greater than one kilometre in diameter. There are nearly 150 known meteorite impact sites around the world. Many more would undoubtedly have fallen into the oceans. In Chad, Northern Africa, the Aorounga craters seem to suggest a chain of impact sites. On June 30, 1908, something exploded above the Tunguska River in central Siberia. The most plausible explanation for this event is that a meteorite was destroyed by its passage through our atmosphere, exploding just before impact with the power of a nuclear detonation. Our planet has obviously not escaped its fair share of extra-terrestrial collisions and near-collisions.
Within some of the world's great myth cycles - Greek, Egyptian, Sumarian, Judaen, Mesopotamian - there is a persistent allusion to some recurrent celestial cataclysm that visits its doom upon the Earth. British author Alan Alford has written books on the subject, among them The Atlantis Secret,The Phoenix Solution and When the Gods Came Down. Alford has speculated that the comets, meteors and asteroids are the remnants of a planet that existed aeons ago, but exploded, showering the inner Solar System with its debris. Alford maintains that the planet itself was a living organism (much as in the Gaia Hypothesis about our own planet). Therefore its explosion conveyed a 'breath of life' to the worlds around it. Physically, the bits and pieces fundamental to building living organisms arrived aboard the huge chunks of rock that rained down on our planet some 600 million or more years ago, where conditions were suited to the evolution of life. Spiritually, the life force of this expunged world was transferred to us as well. Astronomer Tom van Flandern postulates in his book Dark Matter, Missing Planets and New Comets that "there may have been an even earlier planet that also exploded". As the remnants of these worlds found an orbit within the Oort Cloud, a huge reservoir of comets theoretically extending halfway to the our nearest neighbour star, their gravities began to exert pressure on the Earth whenever their orbits approached us, setting off massive earthquakes and other cataclysmic events.
Panspermia, that is knowledge that the seeds of life on this planet arrived with asteriods and meteorites that bombarded our Earth, mostly after the explosion of this nearby 'living' planet, is also fundamental to Alford's view. He cites this specifically in When the Gods Came Down, linking the battle of Zeus and the Titans to the founding of a meteorite cult and the Oracle of Delphi. This famous meteorite was apparently known to the Greeks, according to Alford, as "the great navel-stone of the Earth".
Yet there were undoubted cycles of cataclysmic thought. What happened to the Gold, Silver and Bronze civilisations of man? What is this extra-terrestrial calamity that seems to visit its doom upon us at regular intervals?
I remember hearing about Nemesis when the theory first came to light and, I must admit, it really captured my imagination. In the early '80s, Richard Muller of the University of California, formulated a hypothesis concerning a companion star for our own Sun. In his latest paper Measurement of the Lunar Impact Record for the Past 3.5 Billion Years and Implications for the Nemesis Theory, he says "that passages of the solar companion, Nemesis, through the Oort Cloud would trigger comet showers". This star is probably a common red dwarf which enters our Solar System every 26 million years or so, disrupting the Oort Cloud debris and sending it on a collision impact with the Earth. Companion stars, or binary star systems, are so common as to probably be deemed the norm, at least in this galaxy. The larger star (in this case, our Sun) has a much smaller orbit than the smaller, which can orbit light years away from its companion. The problem is that, when its orbit does come close to that of our own Sun, its gravity dislodges comets from their own orbits, raining death upon the Earth for up to two million years at a time. Richard Muller contends on his website that "Nemesis would be visible from Earth with binoculars or perhaps a small telescope if we knew which of the thousands of visible stars out there to look at".
The evidence for this is cited as the regular events of mass extinction suffered by life on planet Earth. Out of the six major documented mass extinctions, two are theorised to have been caused directly by meteorite hits. A further three have been blamed upon glaciation, which may have been a result of some global catastrophe (meteor strike). However, only the last extinction, responsible for wiping out the dinosaurs 65 million years ago, can almost conclusively be blamed upon this theory. Because of the extreme geological ages involved, evidence is hard to find, although New Scientist recently reported that evidence has come to light that the epoch preceding the dinosaurs was actually brought to an end by a single cataclysmic event. We are, debatably, in the middle of a seventh mass extinction event - this one brought about by the excesses of our own species. Because of this data, along with that of the more minor extinction events, the figure of 26 million years has been speculated as the period of orbit for Nemesis.