They were simply groups of stars in the sky that people wanted to record for posterity. In fact, back then, the constellations as we know them today didn’t even exist. The earliest depictions of the stars date back tens of thousands of years and typically show constellations like Orion, Taurus or the night sky’s most famous star cluster, the Pleiades. This star chart originates from 8th century China and depicts the stars around the north celestial pole. Instead, they typically recorded their observations of the stars on cave walls.
They didn’t have the luxury of smartphones and apps. Imagine trying to get from point A to point B by simply heading in the right general direction, somewhere “over there.” Imagine trying to find the Whirlpool Galaxy when you only know that it’s in the constellation of Canes Venatici. We don’t need those paper star charts, right? They’re a relic of bygone days that, like the road atlas you used to carry in your car, are simply a reminder of a time when getting lost was easy and finding your way was hard. Today we have computerized telescopes and apps that tell us where we should look. There were days when you’d go out for a drive and just explore, just to discover previously unseen sights, but how many of us do that anymore? It’s the same with the stars. It took time and it took planning and you had to know what you were doing. You had to navigate your way with the aid of a paper map. Twenty years ago, the technology was still in its infancy and thirty years ago it was just a twinkle in Steve Jobs’ eye. Nowadays we can travel from point A to point B by simply opening an app on our phone and following directions. Things have changed a lot over the past ten thousand years or so. This ecliptic plane forms a 23 degree angle with the celestial equator since the Earth is tilted 23 degrees on its axis.Charles Messier’s star chart of 1764, showing the curved path of a comet. The equator would become the celestial equator, the poles extended out would hit the position in space over them called the north and south celestial poles and the plane that is perpendicular or forms a right angle to the sun’s axis is called the ecliptic plane. Another way of looking at the celestial sphere is imagine being inside a hollow, transparent earth standing at the center and looking out into space to see where the stars and other celestial objects line up with the coordinates on the Earth’s surface. This sphere is basically an expansion of the reference points on the Earth’s surface such as the equator, the poles, the longitudes and latitude lines out into space. All objects in the night sky are set against a background called the celestial sphere. Understanding The Celestial Sphereįinally, before you can start discovering the wonders of the night sky you must understand how the locations of the planets, stars, nebulae and galaxies are determined. Therefore, any illumination needed at this point must be from a red light source since this wavelength has the least effect on the reflexive response of the pupils to light. Once your eyes are dark-adapted they must be protected from bright white light.
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