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According to archaeologists and anthropologists, hominids have been walking the surface of this planet for a couple of million years. Despite the changes in the complexity of these early humans, and the ever-changing nature of the environment in which they have been evolving, there is one phenomenon that has been pretty much constant for us: it's been visible to everyone for half of the day, and in half of our sphere of vision. When the setting sun darkens the sky, and vision shuts down to a few yards - or as far as the available source of lighting can provide - the stars shine brightly above us.
Some of the earliest human inscriptions and paintings have illustrated man's awareness of this stunning spectacle, and there are few people even now that can look up on a clear night and not be moved at a very fundamental and existential level, given enough time, or at least the right amount of alcohol. Thoughts often turn to other worlds - of strange alien creatures on distant planets who might also be looking up into their own night skies and watching our little sun twinkling, and wondering the same thing as us - is there anyone out there?
It is fundamental to 'the human condition' to wonder about our place amidst the world we see around us. Man's natural tendency to satisfy his curiosity clicked in as soon as he had any luxury time on his hands - in other words, when he had food and shelter and could protect himself from those animals who proved less amenable to the hunting-and-killing agenda. Those who studied the stars soon realised that their movement was, in fact, subtly linked to events on the ground - the seasonal changes in climate, the availability of food and water, and the fertility cycles of all the living things on Earth, including humans themselves. For this reason, those who became well-versed in the study of the stars, and therefore correspondingly knowledgeable about when to travel, when to hunt, and when to prepare for the future, were seen to have potent powers of prediction, and were often raised to high levels of social stature. Priests, shamans, seers, soothsayers - all were feared and respected, and many made a rather comfortable living for themselves on account of this. After all, they weren't too primitive to see how they could take advantage of their wisdom!
Understanding the Universe
In the last few thousand years, as mankind's understanding of the stars grew, navigators and travellers used their positions to guide them across the featureless land- or seascapes. The Greeks, the Arabs, the Chinese and the Egyptians studied and recorded celestial phenomena with obsessive diligence, and in so doing discovered a great deal about their own planet - that it was very large and round, that it rotated about its axis once a day, and that it was not the centre of the universe after all, but moved around the Sun. This radical change in thought attracted much anger from the Church, which had always had a monopoly on belief systems and man's place in the universe. As the physical model seemed to be able to explain an increasing amount about the world in which we lived, the layers of mystery surrounding our daily lives fell away one by one like the layers of an onion.
This cycle of watching, recording, theorising and spotting patterns creates a sort of self-feeding knowledge engine that is responsible for our mental development as intelligent beings. For example, through observation of the planets' movements in the night sky a few hundred years ago, Kepler worked out the mathematical rules of orbiting bodies. Goddard then applied those same rules to theoretical rockets and spacecraft, and a hundred or so years later we use those same laws to launch communications satellites and space telescopes and interplanetary probes. These in turn send back even more observations to us, and allow us to continue making theories and exploring the universe around us ever more deeply. It's a knock-on effect of observation, understanding, experimentation, and then further observation, and I think we can safely assume that we'll never be in a position where there's nothing left to find out about. Astronomical observations just happen to have been some of the earliest that were available to us without needing any specialised tools - anyone could look into the sky and see it going on right there. Maybe that's a large part of the stars' attraction, the fact that you can see them on any clear night, but you can't touch them or play with them or experiment with them at all - all you can do is look at them and wonder. Until recently, that is.
Now that we humans have become extremely adept at manufacturing the tools we need to satisfy our curiosity, we have built telescopes to allow us to see further and more clearly, and have built spacecraft to probe our nearest celestial neighbours, the planets of the solar system. We have even stepped on our own Moon, all in the name of curiosity and experiment1. After all, that's what man is - an imaginative, adaptive and endlessly curious creature that simply must find out about everything we can see around us. And as the stars in the night sky have been with us all through our development, it is only natural that they should be at the focus of our oldest imaginings.
The kind of work that goes on in astronomy today is mostly research-based. There is so much that we can see with the hugely powerful telescopes we have created, but still a great deal that we can't explain. A lot of work is done in the purely theoretical arena, using the most abstract of mathematical tools to predict the kind of things that might be possible without even going near a telescope. This was one of Albert Einstein's best tricks; he explored mathematical theories on paper, then said what kinds of things you should be able to see under certain circumstances, and hey presto - the theories fitted the observations!
There are also some practical considerations to be explored with astronomy, most notably the threat posed to Earth and mankind by meteorite and comet impacts, and also any longer-term plans for the expansion of mankind into space, onto the neighbouring planets, and out into the Galaxy. While this kind of thing is incredibly expensive and resource-consuming, we use astronomy to collect as much information as possible about the universe, so as to be armed and forewarned as much as possible before we commit ourselves to building spacecraft and risking our lives to explore the universe. For good examples of modern astronomy applications, consider the Voyager missions, the Hubble Space Telescope, and the SETI Research Project.
Of course, there is plenty of room for amateur and hobby astronomy. Anyone with a pair of eyes, binoculars or a small telescope can search for and explore the heavens. There are meteor showers to watch, the planets to track down, and, if you're really lucky, comets and asteroids to spot.
And that's one of the most extraordinary things about the subject - anyone with a keen interest can, just by looking in the right place and in the right way, actually carry out scientific work at the very forefront of a scientific discipline! You can't say the same thing for any other science. You never hear anything like: 'Well, I was footling around with the electron synchrotron that I built last year in the garden shed, and I was just colliding a proton with a cloud of super-energetic gluons when guess what happened...?!' and so forth. The very brightest comet that has ever been seen by modern man, Hale-Bopp, was discovered by two amateurs who just happened to stumble upon it, albeit from different sides of the planet.
As a footnote, it should be made clear that astronomy is not the same as astrology. Astronomy is a science - only those theories supported by fact and diligent observation are considered as explanations of the world around us. True, there are many observations that we cannot yet explain, but the rules of science are strictly adhered to. Astrology is not a science. Its ideas are based upon the observation of the stars and planets, but the theories produced from those observations (ie that they directly affect individuals' lives each and every moment) are not constructed upon facts or according to any scientific regulation.
While astronomy and astrology used to be one and the same, particularly for the Egyptian and Mayan civilisations, today's modern and objective approach to the subject creates a very clearly defined boundary between them.