News

Did the ancient Egyptians record the period of eclipsing binary Algol?

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.

Picture This

Saturn’s moon Prometheus seen up close

NASA’s Cassini spacecraft spied details on the pockmarked surface of Saturn’s moon Prometheus (86 kilometres, or 53 miles across) during a moderately close flyby on 6 December 2015. This is one of Cassini’s highest resolution views of Prometheus, a moon which orbits Saturn just interior to the narrow F ring, which is seen here at top.

Observing

See star λ Geminorum’s lunar hide and seek on 29 November

Early risers in the northeast of England and Scotland with clear skies can see naked-eye star lambda (λ) Geminorum, otherwise known as Alkibash, slip behind the southern polar regions of an 18-day-old waning gibbous Moon close to 5am GMT on Sunday, 29 November. However, for a select number of northern observers this will be a special grazing lunar occultation.