Astronomers discovered ancient Egyptian observations of a variable star

Astronomers of University of Helsinki can now explain why the period of Algol has increased by about 0.017 days. The period increase during the past three millennia could have been caused by the observed mass transfer between the two members of this binary. In fact, this would be the first observation that confirms the period increase of Algol and it also gives an estimate of the mass transfer rate. The ancient Egyptians have thus made accurate measurements that provide useful constraints for modern astronomers. Read more