Астрономдық объектінің айналу периоды

Time an astronomical object takes to complete one orbit around another object

The orbital period (also revolution period) is the amount of time a given astronomical object takes to complete one orbit around another object. In astronomy, it usually applies to planets or asteroids orbiting the Sun, moons orbiting planets, exoplanets orbiting other stars, or binary stars. It may also refer to the time it takes a satellite orbiting a planet or moon to complete one orbit. For celestial objects in general, the orbital period is determined by a 360° revolution of one body around its primary, e. g. Earth around the Sun. Periods in astronomy are expressed in units of time, usually hours, days, or years.

For celestial objects in general, the orbital period typically refers to the sidereal period, determined by a 360° revolution of one body around its primary relative to the fixed stars projected in the sky. For the case of the Earth orbiting around the Sun, this period is referred to as the sidereal year. This is the orbital period in an inertial (non rotating) frame of reference. Orbital periods can be defined in several ways. The tropical period is more particularly about the position of the parent star. It is the basis for the solar year, and respectively the calendar year. The synodic period refers not to the orbital relation to the parent star, but to other celestial objects, making it not a merely different approach to the orbit of an object around its parent, but a period of orbital relations with other objects, normally Earth, and their orbits around the Sun. It applies to the elapsed time where planets return to the same kind of phenomenon or location, such as when any planet returns between its consecutive observed conjunctions with or oppositions to the Sun. For example, Jupiter has a synodic period of 398.8 days from Earth; thus, Jupiter's opposition occurs once roughly every 13 months. There are many periods related to the orbits of objects, each of which are often used in the various fields of astronomy and astrophysics, particularly they must not be confused with other revolving periods like rotational periods. Examples of some of the common orbital ones include the following:

The synodic period is the amount of time that it takes for an object to reappear at the same point in relation to two or more other objects. In common usage, these two objects are typically Earth and the Sun. The time between two successive oppositions or two successive conjunctions is also equal to the synodic period. For celestial bodies in the solar system, the synodic period (with respect to Earth and the Sun) differs from the tropical period owing to Earth's motion around the Sun. For example, the synodic period of the Moon's orbit as seen from Earth, relative to the Sun, is 29.5 mean solar days, since the Moon's phase and position relative to the Sun and Earth repeats after this period. This is longer than the sidereal period of its orbit around Earth, which is 27.3 mean solar days, owing to the motion of Earth around the Sun. The draconitic period (also draconic period or nodal period), is the time that elapses between two passages of the object through its ascending node, the point of its orbit where it crosses the ecliptic from the southern to the northern hemisphere. This period differs from the sidereal period because both the orbital plane of the object and the plane of the ecliptic precess with respect to the fixed stars, so their intersection, the line of nodes, also precesses with respect to the fixed stars. Although the plane of the ecliptic is often held fixed at the position it occupied at a specific epoch, the orbital plane of the object still precesses, causing the draconitic period to differ from the sidereal period. The anomalistic period is the time that elapses between two passages of an object at its periapsis (in the case of the planets in the Solar System, called the perihelion), the point of its closest approach to the attracting body. It differs from the sidereal period because the object's semi major axis typically advances slowly. Also, the tropical period of Earth (a tropical year) is the interval between two alignments of its rotational axis with the Sun, also viewed as two passages of the object at a right ascension of 0 hr. One Earth year is slightly shorter than the period for the Sun to complete one circuit along the ecliptic (a sidereal year) because the inclined axis and equatorial plane slowly precess (rotate with respect to reference stars), realigning with the Sun before the orbit completes. This cycle of axial precession for Earth, known as precession of the equinoxes, recurs roughly every 25,772 years. Periods can be also defined under different specific astronomical definitions that are mostly caused by the small complex external gravitational influences of other celestial objects. Such variations also include the true placement of the centre of gravity between two astronomical bodies (barycenter), perturbations by other planets or bodies, orbital resonance, general relativity, etc. Most are investigated by detailed complex astronomical theories using celestial mechanics using precise positional observations of celestial objects via astrometry.

The concept of synodic period applies not just to the Earth, but also to other planets as well, and the formula for computation is the same as the one given above. Here is a table which lists the synodic periods of some planets relative to each other:
+ Orbital period (years) Relative to Mars Jupiter Saturn Chiron Uranus Neptune Pluto Quaoar Eris Sun 1.881 11.86 29.46 50.42 84.01 164.8 248.1 287.5 557.0 Mars 2.236 2.009 1.954 1.924 1.903 1.895 1.893 1.887 Jupiter 19.85 15.51 13.81 12.78 12.46 12.37 12.12 Saturn 70.87 45.37 35.87 33.43 32.82 31.11 2060 Chiron 126.1 72.65 63.28 61.14 55.44 Uranus 171.4 127.0 118.7 98.93 Neptune 490.8 386.1 234.0 Pluto 1810.4 447.4 50000 Quaoar 594.2

Binary starOrbital period. AM Canum Venaticorum 17.146 minutes Beta Lyrae AB 12.9075 days Alpha Centauri AB 79.91 years Proxima Centauri – Alpha Centauri AB 500,000 years or more