Daniel Pope

The accumulated knowledge about our Universe is just phenomenal. I value and appreciate the great work of all of the astronomers of the past. But there are times when I go outside and look at the night sky and I push all that aside.

As Venus, Mars, and Saturn have moved close together in our western sky I have been thinking about the very first humans who made marks or structures indicating they were closely observing and recording the night sky. I would assume the first step would be to just record the stars and their positions night after night – season after season – year after year. What if I put myself in that position? Trying to see the figures of animals or shapes or making up stories associated with different star groups would seem a natural way to start. Maybe I would have been capable of that much. Some time ago I decided to learn about the night sky. First I learned the bright major asterisms and constellations. As they move across the sky both throughout a given night and a given season their orientation changes and so a second feat is to learn to recognize them in all of their different orientations. There are quite a few but it is possible to learn them in a reasonable amount of time. What makes it not too difficult is that all the stars stay in the same fixed position relative to all the other stars in the sky. Put myself back in ancient times and I could have accomplished the same thing long ago. However what I would have noticed and no doubt had difficulty with were the 5 or 6 or 7 “stars” that did not stay in the same position relative to all the other stars. If I had been the first observer I would have been puzzled and wondered why these 5 or 6 or 7 “stars” moved around the sky. The fact that they move relative to all the other stars makes them more difficult to learn and keep track of. So, on any given night when you look at the night sky how do you know which ones are the ones that move? When I look at the night sky all the points of light look about the same except some are brighter than others.

If I had been the first observer I would have had to develop a method of marking in order to keep track of the 5 or 6 or 7 that moved. By now you might be wondering why I keep saying 5 or 6 or 7 instead of saying just 5 (Mercury, Venus, Mars, Jupiter, Saturn). Originally Mercury was recorded as two different moving “stars” and the same was true for Venus. These two moving stars would sometimes appear in the twilight in the west after sunset and then there were two moving “stars” that would appear in the morning twilight in the east before sunrise. In each case one (Mercury) was very low and was visible for only a few days while the other (Venus) was much higher and was visible for about nine months at a time.

Pythagoras (570 – 495 BC) is credited with being the first to propose that the two moving evening “stars” were the same as the two moving morning “stars” and Pythagoras came long after the original observer.

Next week we will look directly overhead to observe big and bright and small and faint star groups.

Clear skies.