Changes

A '''year (yr)''' is about 365 [[day]]s (except in a [[leap year]]). It is the time it takes the [[Earth]] to go completely around ([[orbit]]) the [[sun]] once. A year is actually almost 365.25 days long, but the [[Gregorian calendar|Gregorian]] and [[Julian calendar|Julian]] [[calendar]] has 365 days, except in a [[leap year]], which has 366 days.<ref>{{Cite web|title=What Is a Leap Year? {{!}} NASA Space Place – NASA Science for Kids|url=https://spaceplace.nasa.gov/leap-year/en/|access-date=2023-05-17|website=spaceplace.nasa.gov}}</ref>

The '''year''' (symbol: '''y''' or '''a''', also known as the '''annum''' or '''annus''') is about 365 [[day]]s (except in a [[leap year]]). It is the time it takes the [[Earth]] to go completely around ([[orbit]]) the [[sun]] once. A year is actually almost 365.25 days long, but the [[Gregorian calendar|Gregorian]] and [[Julian calendar|Julian]] [[calendar]] has 365 days, except in a [[leap year]], which has 366 days.<ref>{{Cite web|title=What Is a Leap Year? {{!}} NASA Space Place – NASA Science for Kids|url=https://spaceplace.nasa.gov/leap-year/en/|access-date=2023-05-17|website=spaceplace.nasa.gov}}</ref>

The year starts on [[January 1]] and ends on [[December 31]] in the [[Gregorian calendar|Gregorian]] and [[Julian calendar]] but a [[fiscal year]] or a [[school year]] can start or end on a different day.

The year starts on [[January 1]] and ends on [[December 31]] in the [[Gregorian calendar|Gregorian]] and [[Julian calendar]].  A [[fiscal year]] or a [[school year]] can start or end on a different day.

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

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

* a '''solar''' year, also called '''tropical year''', is based on the [[season]]s.  The [[Gregorian calendar]] is 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 vernal [[equinox]] to vernal equinox, or from summer [[solstice]] to summer solstice.  The word "tropical" in this sense comes from the Greek ''tropikos'' meaning "turn".

* a '''Solar''' year, also called '''tropical year''', is based on the [[season]]s.  The [[Gregorian calendar]] is 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 vernal [[equinox]] to vernal equinox, or from summer [[solstice]] to summer solstice.  The word "tropical" in this sense comes from the Greek ''tropical'' meaning "turn".

* a '''lunar''' year is based on the [[moon]] and is  

* a '''Lunar''' year is based on the [[Moon]] and is  

* usually 12 [[Month|lunar months]] (29 days, 12 [[hour]]s, 44 [[minute]]s each) or 354/355 days long.

* usually 12 [[Month|Lunar months]] (29 days, 12 [[hour]]s, 44 [[minute]]s each) or 354 or 355 days long.

* a '''sidereal''' year measures the time between when a selected [[star|fixed star]] is highest in the [[night|night]] [[sky]].

* a '''sidereal''' year measures the time between when a selected [[star|fixed star]] is highest in the [[night|night]] [[sky]].

* an '''anomalistic year''' is the difference between the times when the Earth gets closest to the sun.

* an '''anomalistic year''' is the difference between the times when the Earth gets [[Perhelion|closest to the Sun]].

* an '''eclipse''' year 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 when [[eclipse]]s can happen.

* an '''eclipse''' year 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 when [[eclipse]]s can happen.

Solar and lunar years are used by different [[calendar]]s for daily life. The other measurements are used by [[astronomer]]s.

Solar and lunar years are used by different [[calendar]]s for daily life. The other measurements are used by [[astronomer]]s.

* '''''Ma''''' (for meganum) — a unit of time equal to one [[million]] years. The suffix "Ma" is often used in scientific disciplines such as geology, paleontology, and [[astronomy]] to 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.

* '''Ma''' (for megaannum) — one [[million]] years. The term "Ma" is often used in scientific disciplines such as geology, paleontology, and [[astronomy]] to 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 specific [[Christian calendar|calendar]] is provided for the liturgical year.

A specific [[Christian calendar|calendar]] is provided for the liturgical year.