A solar calendar is a calendar whose dates indicate the position of the earth on its revolution around the sun (or equivalently the apparent position of the sun moving on the celestial sphere).

If the position of the earth in its orbit around the sun is reckoned with respect to the equinox, the point at which the orbit crosses the celestial equator, then its dates accurately indicate the seasons, that is, they are synchronized with the declination of the sun. Such a calendar is called a tropical solar calendar.

The duration of the mean calendar year of such a calendar approximates some form of the tropical year, usually 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, a method called "intercalation", the inserted day being "intercalary".

The Zoroastrian calendar is a religious calendar used by adherents of the Zoroastrian faith, and is an approximation of the tropical solar calendar.

Angus MacLise (March 4, 1938, Bridgeport, Connecticut – June 21, 1979, Kathmandu, Nepal) was an American percussionist, composer, poet, occultist and calligrapher probably best known as the first drummer for the Velvet Underground.

MacLise was a member of La Monte Young's Theater of Eternal Music, with John Cale, Tony Conrad, Marian Zazeela and sometimes Terry Riley. He contributed to the early Fluxus newspaper VTre, edited by George Brecht, and was also an early member of The Velvet Underground, having been brought into the group by flatmate John Cale when they were living at 56 Ludlow Street in Manhattan.

MacLise played bongos and hand drums during 1965 with the first incarnation of the Velvet Underground. Although the Velvets regularly extemporised soundtracks to underground films during this era, MacLise never officially recorded with them, and is often considered something of a shadowy, legendary figure in their history. When the opportunity of the band's first paying gig in November 1965 arose, MacLise promptly quit, suggesting the group were selling out.