!Altitude
The direct angular distance between the sun and the horizon, measured vertically
!Azimuth
The bearing of the sun measured as an angle around the horizon eastwards starting from north as the zero point.
!Right Ascension
Horizontal coordinate of the sun on the celestial sphere. It is the equivalent of longitude on the Earth.
!Declination
Vertical coordinate of the sun on the celestial sphere. It is the equivalent of latitude on the Earth.
!Twilights
Twilight is the period before sunrise and after sunset when the sky is partially illiminated by scattered sunlight.
There are 3 types of twilight:
 - Civil twilight is defined as the period when sun's altitude between -050' (sunrise/sunset) and -6.
 - Nautical twilight is defined as the period when sun's altitude between -6 and -12.
 - Astronomical twilight is defined as the period when sun's altitude between -12 and -18.
!Sunrise/Sunset
Sunrise and sunset are defined as the time at which the apparent upper limb of the sun is on the astronomical horizon.
!Transit Time
Transit time is defined as the time at which the sun passes observer's meridean (south direction for northern hemisphere and north direction for southern hemisphere). At transit time sun normally reaches maximal altitude.
!Day Length
Day length is defined as the period between sunrise and sunset.
!Daylight saving time
An adjustment to the normal civil time, introduced in some contries for part of the year. One of the main reasons for adjustment is to arrange for the habitual working day to occur as far as possible during the hours of daylight.
!Twilight length
Twilight length in this program represents period from beginning of certain type of a twiligth up to sunrise in the morning, and the period from the sunset up to ending of certain type of a twilight in the evening.
!Max. Altitude
Maximal altitude is an altitude of the sun at transit time. (In the locations closes to poles, it is not always right).