Supernova?

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Supernova
Is this a Supernova? Photo by John Barentine, Apache Point Observatory

I picked up the story Ancient rock art chron­icles explod­ing star yes­ter­day, but I don’t know what to make of it. It’s another example of how a news story misses what is so interesting.

Briefly, a talk at the 208th meet­ing of the American Astronomical Society sug­gests that a Hohokam pet­ro­glyph might depict the great super­nova of AD 1006. The rem­nants of this explo­sion can only be seen through a tele­scope today, but at the time it may have been the bright­est star in the sky by a long way. Bright enough to read by. It’s not sur­pris­ing that there are his­tor­ical records of it around the world, but no record of it has been found in North America till now.

The talk relates an image to another pet­ro­glyph depict­ing Scorpius. This is what I find both really inter­est­ing and a bit odd, because I don’t know how they worked out the pet­ro­glyph was a con­stel­la­tion and that it was Scorpius. The pic­ture looks like a scor­pion, but does that auto­mat­ic­ally make it a con­stel­la­tion? If it does then must this scor­pion be in the same part of the sky as the Graeco-Roman con­stel­la­tion Scorpius?

The only con­stel­la­tion records I could get my hands on from the region are the Navajo con­stel­la­tions. In these one part of Scorpius, along with Sagittarius, is part of a man with a staff. The other part is an entirely dif­fer­ent con­stel­la­tion, the Rabbit Tracks. I’ve asked on HASTRO-L and Steve McCluskey has said that there’s no reason to assume con­tinu­ity between Navajo and Hohokam cul­tures, they’re too far apart in time, geo­graphy and eco­nomic pat­terns, so you wouldn’t expect the astro­nom­ies to be similar.

Unlike the Navajo there is no liv­ing Hohokam people so inter­pret­a­tion has to be purely archae­olo­gical. Unfortunately (?) there are thou­sands upon thou­sands upon thou­sands of pet­ro­glyphs in the American south­w­est. Simply pick­ing glyphs to fit a the­ory would be easy, and with such a bright star it would be really really strange if no-one drew it. So the news report tells me noth­ing I can get excited about. It tells me that ancient Americans saw a super­nova which shone around mag­nitude –7.5 but I could have guessed that. The really excit­ing and archae­olo­gic­ally use­ful bit, that it might be pos­sible to identify con­stel­la­tions in pet­ro­glyphs, is com­pletely glossed over.

I’ll have to wait for the pub­lic­a­tion before I can make sense of it.