Year

Ayearis about 365days(except in aleap year). It is the time it takes theEarthto go completely around (orbit) thesunonce. A year is actually almost 365.25 days long, but acalendarhas 365 days, except in aleap year,which has 366 days.

The year starts onJanuary 1and ends onDecember 31in theGregorian calendar,but afiscal yearor aschool yearcan start on a different day of the year.

There are several ways used to measure the length of a year.

• asolaryear, also calledtropical year,is based on theseasons.TheGregorian calendaris based on a tropical year of 365.2425 days. This is the time that the Sun takes to return to the same position in the cycle of seasons, as seen from Earth; for example, the time from vernalequinoxto vernal equinox, or from summersolsticeto summer solstice. The word "tropical" in this sense comes from the Greektropikosmeaning "turn".
• alunaryear is based on themoonand is usually 12lunar months(29 days, 12hours,44minuteseach) or 354 days long.
• asiderealyear measures the time between when a selectedfixed staris highest in thenightsky.
• ananomalistic yearis the difference between the times when the Earth gets closest to the sun.
• aneclipseyear is the time between node passages. This is when the sun moves through a part of the sky where it is possible for the sun, Earth and moon to be in a line. It is also wheneclipsescan happen.

Solar and lunar years are used by differentcalendarsfor daily life. The other measurements are used byastronomers.

• Ma(for meganum) — a unit of time equal to onemillionyears. The suffix "Ma" is often used in scientific disciplines such as geology, paleontology, andastronomyto signify very long time periods into the past or future. The simpler term "mya"for" million years ago "is generally preferred on this wiki as being intuitively more simple for non-technical readers.

A specificcalendaris provided for the liturgical year.