Month: July 2025

DAY
A 24-hour period based on one full rotation of the Earth.

LUNISOLAR CALENDAR
A calendar that combines elements of both solar and lunar cycles, such as the Chinese calendar.

LUNAR CALENDAR
A calendar system based on the phases of the Moon, like the Islamic calendar.

SOLAR CALENDAR
A calendar based on the Earth’s orbit around the Sun, such as the Gregorian calendar.

CALENDAR
A system of organizing days for social, religious, and administrative purposes, often based on astronomical observations.

TIMEKEEPING
The process of measuring and tracking time using various devices and methods.

CELESTIAL EQUATOR
The projection of Earth’s equator onto the celestial sphere.

MERIDIAN
An imaginary line passing through the zenith and celestial poles.

NADIR
The point directly below an observer on Earth.