one revolution of earth around the sun is called a
sidereal year
title: Day text: daytime may extend beyond one 24 hour period and could even extend to months Day A day, a unit of time, is approximately the period of time during which the Earth completes one rotation with respect to the Sun ("solar day"). In 1960, the second was redefined in terms of the orbital motion of the Earth in year 1900, and was designated the SI base unit of time. The unit of measurement "day", was redefined as 86 400 SI seconds and symbolized "d". In 1967, the second and so the day were redefined by atomic electron transition. A civil day title: Day text: Day A day, a unit of time, is approximately the period of time during which the Earth completes one rotation with respect to the Sun ("solar day"). In 1960, the second was redefined in terms of the orbital motion of the Earth in year 1900, and was designated the SI base unit of time. The unit of measurement "day", was redefined as 86 400 SI seconds and symbolized "d". In 1967, the second and so the day were redefined by atomic electron transition. A civil day is usually 86 400 seconds, plus or minus a possible leap second in Coordinated title: Diurnal motion text: Diurnal motion Diurnal motion (, from "dies", lit. "day") is an astronomical term referring to the apparent motion of celestial objects (e.g. the Sun and stars) around Earth, or more precisely around the two celestial poles, over the course of one day. It is caused by Earth's rotation around its axis, so almost every star appears to follow a circular arc path called the diurnal circle. The time for one complete rotation is 23 hours, 56 minutes, and 4.09 seconds – one sidereal day. The first experimental demonstration of this motion was conducted by Léon Foucault. The relative direction of title: Year text: sidereal year is the time taken for the Earth to complete one revolution of its orbit, as measured against a fixed frame of reference (such as the fixed stars, Latin "sidera", singular "sidus"). Its average duration is days (365 d 6 h 9 min 9.76 s) (at the epoch J2000.0 = January 1, 2000, 12:00:00 TT). Today the mean tropical year is defined as the period of time for the mean ecliptic longitude of the Sun to increase by 360 degrees. Since the Sun's ecliptic longitude is measured with respect to the equinox, the tropical year comprises a complete cycle title: Orbital period text: Orbital period The orbital period is the time a given astronomical object takes to complete one orbit around another object, and applies in astronomy usually to planets or asteroids orbiting the Sun, moons orbiting planets, exoplanets orbiting other stars, or binary stars. For objects in the Solar System, this is often referred to as the sidereal period, determined by a 360° revolution of one celestial body around another, e.g. the Earth orbiting the Sun. The name "sidereal" is added as it implies that the object returns to the same position relative to the fixed stars projected in the sky. When