3 ms·

BTW, 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 bright

BTW, 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 ago
Yep, 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 :)
- teraflop 11y ago
  You might want to read that Wikipedia article more closely; it mentions that Algol was written about by Ptolemy in the 2nd century.
  - codezero 11y ago
    You're totally right, and the variability was in the 1600s – foot in mouth! Thanks for pointing this out to me.