Changes

=== Alignment ===

=== Alignment ===

Sosigenes aligned the calendar so that the spring equinox would fall on March 25 according to observations recorded by Hipparchus. Hipparchus was the standard astronomy reference work of the time. The observations he used are thought to have been made around 135 BC in Alexandria. At this time, the equinox occurred when the Sun entered the constellation Aries, or "first point of Aries." This alignment is still used in astrology. Hipparchus's work has been lost, but it is quoted by Ptolemy in ''Almagast''. The Julian calendar drifts by one day every 138 years. In 8 BC, Augustus removed one day from the month February and added it to August, putting the calendar an additional day out of alignment. At the time of the Council of Nicene in 335, the equinox occurred on March 21.<ref>(335+135)/138 gives us 3.4 days of calendar drift, plus one day for Augustus's reform.</ref> The Gregorian calendar reestablished the alignment at the time of Nicene.

Sosigenes aligned the calendar so that the spring equinox would fall on March 25 according to observations recorded by Hipparchus. Hipparchus was the standard astronomy reference work of the time. The observations he used are thought to have been made around 135 BC in Alexandria. At this time, the equinox occurred when the Sun entered the constellation Aries, or "first point of Aries." This alignment is still used in astrology. Although Hipparchus's work has been lost, it is quoted by Ptolemy in ''Almagest''. The Julian calendar drifts by one day every 138 years. In 8 BC, Augustus removed one day from the month February and added it to August, putting the calendar an additional day out of alignment. At the time of the Council of Nicene in 335, the equinox occurred on March 21.<ref>(335+135)/138 gives us 3.4 days of calendar drift, plus one day for Augustus's reform.</ref> The Gregorian calendar reestablished the alignment at the time of Nicene.

== Later history ==

== Later history ==