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The Ancient Egyptian Discovery of Binary Star Algol’s Period Confirmed
- dang 11y agoAlso https://news.ycombinator.com/item?id=10800225 https://news.ycombinator.com/item?id=10800225.
- Florin_Andrei 11y agoBTW, observing the magnitude variations of Algol with the naked eye is not hard. Spend enough time looking at Perseus from a dark place, and the shifting brightness of that star will eventually become apparent. The article's claim is that this might be the oldest documented observation of the variability of Algol. Previously, the oldest confirmed observation was in the 1600s.
- codezero 11y agoYep, the trick, is to look at the brightness relative to a non-variable, or less variable star. Also, note that the observations of Algol from the 1600s were just the first documentation of the star – observations of variability didn't happen until the 1700s – I'm not smart, I just checked Wikipedia as I was reading up around this topic :)
- codezero 11y agoI was curious whether or not the fact that P_moon being 29.6 (in their data) and P_algol being 2.85 would lead to the chance that they were measuring some other fraction of the periodicity of the Moon, more specifically, 2.96 – which is P_moon divided by the length of an Ancient Egyptian week of 10 days. The linked article doesn't discuss this (that I can find), but an article the same authors posted to Arxiv in 2012 (and updated thereafter) does discuss this and they found that the two periodicities are completely out of phase, so that's pretty neat: http://arxiv.org/abs/1204.6206 http://arxiv.org/abs/1204.6206