An anomalistic year is the amount of time it takes for the Earth to complete one revolution with respect to its apsides.

1620

"Prehistoric" means "before written history", so if there was any astronomy at that time, we won't know the exact year.

In astronomy, a year is defined as the time it takes a planet to make one full orbit around the sun. It is equivalent to the orbital period of a planet, and is typically expressed in terms of Julian Year (which is equal to one Earth year).

2009 is the International Year of Astronomy, the International Year of Natural Fibres, and the International Year of Reconciliation.