Out of line

Every so often, I run into a claim that some archaeological site aligns with a particular astronomical object, and all too often, everyone decides that the alignment is why the site was built where and how it was.

Trying to parse the motives of long-dead people who left nothing in the way of written records is a dicey business.  In fact, sometimes it's hard enough even when you're talking about extant cultures.  This was brilliantly lampooned in Horace Miner's rightly famous 1956 article "Body Ritual Among the Nacirema," which appeared in American Anthropologist, and took a rigorous and scholarly look at the mysterious "shrines" we all have in our houses...

... better known as "bathrooms."  And, of course, reached the wrong conclusions about the purposes of nearly everything in them.

The problem arises because the human brain is a pattern-finding device, so it's often hard to resist our tendency to see a pattern when there is none there.  This is the origin of the phenomenon of ley lines -- which I wrote about twelve years ago, in one of my earliest Skeptophilia posts -- the claim that towns, cities, and religious sites are laid out along "lines of power" generated by some unknown forces in the Earth itself.  There are a couple of completely prosaic reasons this alignment happens:

1. Populated sites in areas with relatively flat topography are frequently connected by straight lines, because as Papa Euclid taught us, the shortest distance between two points is a straight line.
2. More interestingly -- and germane to the pattern-finding tendency referenced above -- if you aren't given any constraints about what particular places you're trying to connect, you can almost always find completely accidental correlations that look like deliberate alignment.

The latter is why the whole topic comes up, because of a fun site I stumbled on called Spurious Alignments: Bad Archaeoastronomy At Your Fingertips.  What this site does is allow you to overlay various astronomical benchmarks (e.g. sunrise on the Winter Solstice, the northernmost point on the horizon where Jupiter rises, and so on) on top of particular geographic locations -- and see what correlations you can find.

One of the best ones anyone's found so far is the airport in Palermo, Italy.  Here are a few of the relevant discoveries:

• Runway 07/25 tracks the relative motions of the Moon.
• Runway 02/20 aligns with the rise of the star Capella.
• Taxiways Bravo and Charlie align with the setting of the star Procyon.
• Taxiway Delta points directly toward the setting of the star Arcturus.

From this, we can clearly see that the Palermo Airport is a site built by ancient astronomers, and the whole complex is an observatory, or possibly the center of a sky-worshiping cult.

The difficulty, of course, is some sites were created because of astronomical alignments.  Many of our distant ancestors knew the motions of the skies better than your average person does today.  A good example, not really explainable any other way, is the famous Sun Dagger on Fajade Butte in New Mexico.  A spiral design carved into the side of a rock facing is across from a crack between two stones, and -- only on the Summer Solstice -- this crack allows light from the Sun at midday to form a "dagger" that perfectly bisects the spiral.

The Sun Dagger is pretty clearly a solstice marker, allowing people to keep track of the seasons in a climate that was hostile to say the least.

But as for most of the other "ancient astronomical observatory" claims -- well, maybe.  It's too easy to find spurious correlations and alignments, especially when there are no rules about what you're trying to get the site to align to.

Or, maybe, the people who built the Palermo Airport really were trying to tell us something.  You never know.

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