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Solar calendar
 
 
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A solar calendar is a calendar
Calendar

A calendar is a system of organize days for a social, religious, commercial or administrative purpose. This organization is done by giving names to periods of time ? typically days, weeks, months and years....
 whose dates indicate the position of the earth on its revolution around the sun
Sun

The Sun , a G V star, is the star at the center of the Solar System. The Earth and other matter orbit the Sun, which by itself accounts for about 98.6% of the Solar System's mass....
 (or equivalently the apparent position of the sun moving on the celestial sphere
Celestial sphere

In astronomy and navigation, the celestial sphere is an imagination rotation sphere of "gigantic radius", concentric spheres and coaxial with the Earth....
).

he position of the earth (or the sun) is reckoned with respect to the equinox
Equinox

Equinoxes occur twice a year, when the tilt of the Earth's axis is inclined neither away from nor toward the Sun, causing the Sun to be located vertically above a point on the equator....
, then the dates indicate the season
Season

A season is one of the major divisions of the year, generally based on yearly periodic changes in weather.Seasons result from the yearly revolution of the Earth around the Sun and the Axial tilt....
 (and so is synchronized to the declination
Declination

In astronomy, declination is one of the two coordinates of the equatorial coordinate system, the other being either right ascension or hour angle....
 of the sun
Sun

The Sun , a G V star, is the star at the center of the Solar System. The Earth and other matter orbit the Sun, which by itself accounts for about 98.6% of the Solar System's mass....
). Such a calendar is called a tropical solar calendar.

The mean calendar year of such a calendar approximates some form of the tropical year
Tropical year

A tropical year is the length of 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....
 (typically either the mean tropical year or the vernal equinox year).

The following are tropical solar calendars:

Every one of these calendars has a year of 365 days, which is occasionally extended by adding an extra day to form a leap year
Leap year

A leap year is a year containing one or more extra days in order to keep the calendar year synchronized with the astronomical year or seasonal year....
.

he position of the earth (see above) is reckoned with respect to the fixed stars, then the dates indicate the zodiacal constellation near which the sun can be found.






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Encyclopedia


A solar calendar is a calendar
Calendar

A calendar is a system of organize days for a social, religious, commercial or administrative purpose. This organization is done by giving names to periods of time ? typically days, weeks, months and years....
 whose dates indicate the position of the earth on its revolution around the sun
Sun

The Sun , a G V star, is the star at the center of the Solar System. The Earth and other matter orbit the Sun, which by itself accounts for about 98.6% of the Solar System's mass....
 (or equivalently the apparent position of the sun moving on the celestial sphere
Celestial sphere

In astronomy and navigation, the celestial sphere is an imagination rotation sphere of "gigantic radius", concentric spheres and coaxial with the Earth....
).

Tropical solar calendars

If the position of the earth (or the sun) is reckoned with respect to the equinox
Equinox

Equinoxes occur twice a year, when the tilt of the Earth's axis is inclined neither away from nor toward the Sun, causing the Sun to be located vertically above a point on the equator....
, then the dates indicate the season
Season

A season is one of the major divisions of the year, generally based on yearly periodic changes in weather.Seasons result from the yearly revolution of the Earth around the Sun and the Axial tilt....
 (and so is synchronized to the declination
Declination

In astronomy, declination is one of the two coordinates of the equatorial coordinate system, the other being either right ascension or hour angle....
 of the sun
Sun

The Sun , a G V star, is the star at the center of the Solar System. The Earth and other matter orbit the Sun, which by itself accounts for about 98.6% of the Solar System's mass....
). Such a calendar is called a tropical solar calendar.

The mean calendar year of such a calendar approximates some form of the tropical year
Tropical year

A tropical year is the length of 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....
 (typically either the mean tropical year or the vernal equinox year).

The following are tropical solar calendars:
  • Gregorian calendar
    Gregorian calendar

    The Gregorian calendar is the internationally accepted civil calendar. It was first proposed by the Calabrian doctor Aloysius Lilius, and decreed by Pope Gregory XIII, after whom it was named, on 24 February 1582 by the papal bull Inter gravissimas....
  • Julian calendar
    Julian calendar

    The Julian calendar, a reform of the Roman calendar, was introduced by Julius Caesar in 46 BC, and came into force in 45 BC . It was chosen after consultation with the astronomer Sosigenes of Alexandria and was probably designed to approximate the tropical year, known at least since Hipparchus....
  • Bahá'í calendar
    Bahá'í calendar

    The Bah?'? calendar, also called the Bad? calendar, used by the Bah?'? Faith, is a solar calendar with regular years of 365 days, and leap years of 366 days....
  • Hindu calendar
    Hindu calendar

    The Hindu calendar used in ancient times has undergone many changes in the process of regionalization, and today there are several regional Indian calendars, as well as an Indian national calendar....
  • Coptic calendar
    Coptic calendar

    The Coptic calendar, also called the Alexandrian calendar, is used by the Coptic Orthodox Church and still used in Egypt. This calendar is based on the ancient Egyptian calendar....
  • Iranian calendar
    Iranian calendar

    The Iranian calendar or Solar Hejri is an astronomical solar calendar and one of the longest chronological records in history and is currently used in Iran and Afghanistan as the main official calendar....
     (Jalali Calendar)
  • Malayalam calendar
    Malayalam calendar

    Malayalam calendar is a solar Orbital period calendar used in the state of Kerala in South India. The era started in the year 825 AD....
  • Tamil calendar
    Tamil calendar

    The Tamil calendar is used in Tamil Nadu, Kerala and Puducherry in India, and by the Tamil people population in Malaysia, Singapore and Sri Lanka....
  • Thai solar calendar
    Thai solar calendar

    The Thai solar calendar, Suriyakati , has been the official and prevalent calendar in Thailand since it was adopted by King Chulalongkorn in 1888, although the Western calendar year is sometimes used in business, and quite often in banking....


Every one of these calendars has a year of 365 days, which is occasionally extended by adding an extra day to form a leap year
Leap year

A leap year is a year containing one or more extra days in order to keep the calendar year synchronized with the astronomical year or seasonal year....
.

Sidereal solar calendars

If the position of the earth (see above) is reckoned with respect to the fixed stars, then the dates indicate the zodiacal constellation near which the sun can be found. Such a calendar is called a sidereal solar calendar.

The mean calendar year of such a calendar approximates the sidereal year
Sidereal year

The sidereal year is a misnomer for solar orbit. It is the time taken for the Sun to return to the same position with respect to the stars of the celestial sphere....
.

The Hindu calendar
Hindu calendar

The Hindu calendar used in ancient times has undergone many changes in the process of regionalization, and today there are several regional Indian calendars, as well as an Indian national calendar....
 and Bengali calendar
Bengali calendar

The Bengali calendar or Bangla calendar is a traditional solar calendar calendar used in Bangladesh and India's eastern states of West Bengal, Assam and Tripura....
 are sidereal solar calendars. They are usually 365 days long, but now and then take an extra day to make a leap year
Leap year

A leap year is a year containing one or more extra days in order to keep the calendar year synchronized with the astronomical year or seasonal year....
.

Non-solar calendars

Calendars that are not solar calendars, include the Islamic calendar
Islamic calendar

The Islamic calendar or Muslim calendar or Hijri calendar is a lunar calendar used to date events in many predominantly Muslim countries, and used by Muslims everywhere to determine the proper day on which to celebrate Islamic holy days and festivals....
 which is a purely lunar calendar
Lunar calendar

A lunar calendar is a calendar that is based on cycles of the moon phase. The only widely used purely lunar calendar is the Islamic calendar or Hijri calendar, whose year always consists of 12 lunar months....
 and calendars synchronized to the synodic period of Venus
Venus

Venus is the second-closest planet to the Sun, orbiting it every 224.7 Earth days. The planet is named after Venus , the Roman mythology goddess of love....
 or to the heliacal rising
Heliacal rising

The heliacal rising of a star occurs when it first becomes visible above the eastern horizon at dawn, after a period when it was hidden below the horizon or when it was just above the horizon but hidden by the brightness of the sun....
s of stars.

Lunisolar calendars

Lunisolar calendar
Lunisolar calendar

A lunisolar calendar is a calendar in many cultures whose date indicates both the moon phase and the time of the solar year. If the solar year is defined as a tropical year then a lunisolar calendar will give an indication of the season; if it is taken as a sidereal year then the calendar will predict the constellation near which the full moo...
s may be regarded as solar calendars, although their dates additionally indicate the moon phase. Because a typical lunisolar calendar has a year made up of a whole number of lunar months, it can't indicate the position of Earth on its revolution around the sun as well as a pure solar calendar can.

See also

  • Analemma calendar
    Analemma calendar

    Analemma calendars are a common feature at science museums and planetariums. They exploit the fact that the sun travels in a predictable pattern over the course of a year and trace the projection of an object's shadow to measure time ....