Imagine living on a world where, every 69 years, the sun disappears in a near-total eclipse that lasts for three and a half years. That is just what happens in a newly discovered system, known only by its astronomical catalogue number TYC 2505-672-1, setting a new record for both the longest duration stellar eclipse and the longest period between eclipses in a binary star system.
A scholarly investigation of the Cairo Calendar papyrus (1244–1163 B.C.) has led researchers at the University of Helsinki to conclude that the ancient Egyptians were aware that the variable star Algol (beta Persei) had a 2.85-day period. Given that the star’s current period is 2.8673 days, this supports the theory that mass transfer between the stars of this eclipsing binary has caused a long-term increase of its orbital period.