Читать книгу: «Simple Stargazing»

Part 1 Getting Started

A fine sunset is worth a picture itself as well as the hint that it’s going to be a fine, clear, starry-skied evening. Just the prompt you need to get you into the stargazing frame of mind.

A Brief History

In the distant past, astronomy and astrology were as one. Ancient rulers needed to know their fortune and, as the sky was where their gods lived, it was also where their destiny lay. Along with all the ‘fixed’ stars of the constellations were seven things that moved: the Sun, Moon and five planets – Mercury, Venus, Mars, Jupiter and Saturn (this was, of course, in the days when everyone believed that the Earth was the centre of the Universe and other sky objects moved round it).

It was an absolute belief that leaders who could understand how these objects moved could stay in control and defeat their enemies. One thing was clear: to these ancient watchers of the skies these seven objects followed a ‘path’ around the heavens – just like a car on a race track that takes the same route round again and again. It was the constellations situated along this ‘path’ that became our 12 famous signs of the zodiac.

Of course, in order to know where any object would be in the zodiac at any given time, a certain amount of calculation was required. This is when the science of astronomy was born. So, strangely, the necessity for fortune-telling encouraged the formation of science. By the way, zodiac means ‘line of animals’ (11 of the original 12 constellations are still animals) and is also linked to the word zoo.

So, why do the planets, Sun and Moon appear to move through the skies? Well, they each appear to move for different reasons. Of course the main movement you see is due to the Earth spinning – this gives us things like sunset, the Full Moon rising over frosty trees, time for your cornflakes for breakfast as the Sun rises, etc. The Moon, if it is up, additionally appears to move extremely slowly hour by hour in front of the stars because it is orbiting the Earth. The Sun changes its position against the stars day by day due to the fact that we are orbiting it. The planets move because they too are orbiting the Sun – plus each planet is moving at a different speed. No wonder it was all difficult to calculate, and indeed it’s hardly surprising that some early astronomers ended up having their heads chopped off, when their erroneous adding up was followed by a total overreaction from their bad-tempered rulers.

Constellations

A word worth defining before we launch ourselves into space is constellation. It’s based on a word from Latin meaning ‘group of stars’. In total you’ll find 88 of them filling the entire sky, but thankfully you don’t need to know them all to enjoy the hours of darkness. Other starry terms that crop up throughout the book are written in bold and explained in the AstroGlossary in here.

The story of organising things up there in the darkness of the night began thousands of years ago with civilisations such as the Sumerians, Babylonians, Egyptians, Greeks and Romans (as well as many other cultures from around the world). They decided the starry skies could do with a bit of order and a tidy up. So they joined up many of the stars, just like a dot-to-dot picture, putting their myths and legends into the sky as they did so.

Don’t think that there was any rhyme or reason for making a particular pattern. For example, Cepheus, King of Ethiopia, and his wife, Queen Cassiopeia, both have constellations named after them, and yet these look like a house and a set of stairs respectively. Imagination is the key here, I feel. As far as these early civilisations were concerned, the gods and goddesses needed a place to reside in the starry vault, so it was probably a case of first come, first served, and pot luck as to which stars were assigned to which group.

We get our earliest knowledge of the constellations from Aratos, the first Greek astronomical poet, in his work Phaenomena (which was probably based on an earlier ‘lost’ work by another Greek, Eudoxus). Then in AD 150 Ptolemy, a Greek working at the great library of Alexandria in Egypt, recorded them in a book known by its Arabic name, Almagest, which means ‘the greatest’. Hundreds of years ago, other astronomers who wanted to be famous added extra groups (some more successfully than others) to give us our present fixed total of 88 constellations.

Constellation names are traditionally written in Latin. This is because Ptolemy’s book was brought from the Middle East to Italy, where it was translated – and Latin, for centuries, was the language of scholars. So, for example, we know the Great Bear as Ursa Major.

Here are all the 88 constellations of the starry skies. Details of those with interesting things to see are given in Parts 2 and 3.