Stonehenge Astronomy V: The Planets

If tying alignments to stars if difficult, then the planets should be easier as there’s only five of them visible to the naked eye from Stonehenge. However it’s hard to argue for any planetary alignments at Stonehenge. The problem is that the planets cross the horizon over much the same range as the Sun or Moon. This means that anything that was a planetary alignment would look like a Sun or Moon alignment. How do you prove it was a planet the observers were interested in?

If you were dealing with a culture with written records like the Mayans then it’s easy. The Mayans did point buildings to face the rising of venus. We know this because they helpfully covered these buildings in Venus glyphs. If other cultures had had the foresight to label their buildings then archaeological life would be a lot easier. I’m inclined to say that there are no traceable planetary alignments and have suggested an experiment which would show the problems, though I don’t know if there’s the time or equipment to do it. June 20 will be quite a busy night with the planets. If you go out at 9:30, which is around sunset and look to see where the sun is setting then you’ll have an aid to find three planets.

Sky chart for 21:30 near Stonehenge. Generated by Heavens-Above.

Venus is the brightest. It’ll be shining like a bright diamond in the West North West. If North is at 12 o’clock, then Venus is at 10 o’clock. Keep your eyes on Venus and the way its moving. After around five minutes you might notice another point about 2° (the width of four little fingernails held from you at arm’s length) to the north and a bit closer to the horizon. It’ll be silver but a lot fainter. That’s Mercury. You’ll need to be quite fast to see this as it’ll be setting shortly. Around 9:50 you could draw a line from Mercury, back through Venus until you hit another point of light about twice the distance away. That’s Saturn.

Saturn (left), Venus (middle), Mercury (right), June 20

You’ll do well to see them. The experiment at the Stonehenge circle would be to try and see them from the centre of the circle. In addition to the problems you have there’s the added problem that the cameras might not have the contrast to see the planets with special equipment, which would be cheating. In addition they’ll lose track of the planets because a problem of being in the middle of a stone circle is that there’s all these whacking great stones in the way.

Stonehenge and stones blocking the distant horizon.

You might stand more of a chance of seeing Jupiter, low but bright in the southern sky. Mars will make an appearance too around 1:30 am on June 21, so if you stop up you’ll be able to see all five planets in one evening. The problem with watching Mars rise is, like watching the planets set, these megaliths keep getting in the way.

Another symbolic connection to the planets might be found in the centre of the circle. There are five central trilithons. Some people have argued that these represent the five visible planets. Perhaps. The Greeks claimed that Pythagoras discovered that the Morning Star and the Evening Star were the same planet, Venus around 500 BC. Did the prehistoric peoples of Britain recognise Venus and Mercury as individual planets, or did they see them both as twin planets with morning and evening versions? We don’t have the historical records. With the planets it would seem that most astronomy is speculation. —–