Solar calendars are the type of calendars which do take the reference of current date and months from the position of the earth with respect to its revolution around the sun. Alternately it may also be defined as the reference taken from the position of the sun moving on the celestial sphere.
Various types of Solar Calendar are used all over the world. To name a few are the Tropical Solar Calendar and Sidereal Solar Calendar.
Examples of Tropical Solar Calendars are the Gregorian calendar, Coptic Calendar, Coptic Calendar, Malayalam and Tamil Calendar and the Thai Solar Calendar. On the other side the Hindu calendar and the Bengali Calendar are examples of the Sidereal Solar Calendars.
The dates of the Tropical Solar Calendars do indicate the season of the year. In case of this type of calendars the position of the earth or alternately the sun is reckoned with reference to equinoxes and in turn the calendar dates are therefore synchronized to the sun's declination. The number of days in an year, in case of such calendars is equal to 365 days and an extra day Is added up for a leap year.
The date and month of a sidereal solar calendar is on the other hand decided by the position of earth from certain fixed stars. The dates of such a calendar are therefore indicative of the zodiacal constellation. The number of days in a year for such calendars is also equal to 365 days and an extra day is adjusted to make a leap year.
One of the most widely used solar calendars in the world is the Gregorian calendar. It was first proposed by Aloysius Lilius and the years are numbered from Jesus' birth year. The Gregorian Calendar is the version of sort of arithmetical calendar. The average year length is calculated to a very high degree of accuracy which is equal to 365.2425 days. The Gregorian Calendar is divided over twelve months. This calendar is followed in Span, Portugal, Great Britain, Norway, Russia, Denmark and a host of other Eastern Asia countries.