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Planetary phase. The evolution of the apparent diameter and phases of Venus. A planetary phase is a certain portion of a planet 's area that reflects sunlight as viewed from a given vantage point, as well as the period of time during which it occurs. The phase is determined by the phase angle, which is the angle between the planet, the Sun and ...
In this situation, the latter planet is said to be superior to the former. In the reference frame of the Earth, where the terms were originally used, the inferior planets are Mercury and Venus, while the superior planets are Mars, Jupiter, Saturn, Uranus and Neptune. Dwarf planets like Ceres or Pluto and most asteroids are 'superior' in the ...
In astronomy, a phase curve describes the brightness of a reflecting body as a function of its phase angle (the arc subtended by the observer and the Sun as measured at the body). The brightness usually refers the object's absolute magnitude, which, in turn, is its apparent magnitude at a distance of one astronomical unit from the Earth and Sun.
Phase angle (astronomy) Phase angle diagram. In observational astronomy, phase angle is the angle between the light incident onto an observed object and the light reflected from the object. In the context of astronomical observations, this is usually the angle Sun -object-observer. For terrestrial observations, "Sun–object–Earth" is often ...
In spherical astronomy, quadrature is the configuration of a celestial object in which its elongation is a right angle (90 degrees), i.e., the direction of the object as viewed from Earth is perpendicular to the position of the Sun relative to Earth. It is applied especially to the position of a superior planet or the Moon at its first and last ...
A giant planet composed mainly of hydrogen and helium gases rather than heavier elements, e.g. Jupiter and Saturn in the Solar System. geocenter The geometric center of the Earth, i.e. the arithmetic mean position of all points within the oblate spheroid that is the precise shape of the Earth. geocentric
Elongation (astronomy) In astronomy, angular separation between the Sun and a planet, with the Earth as a reference point. This diagram shows various possible elongations (ε), each of which is the angular distance between a planet and the Sun from Earth's perspective. In astronomy, a planet's elongation is the angular separation between the ...
A planet (or asteroid or comet) is said to be "in opposition" or "at opposition" when it is in opposition to the Sun. Because most orbits in the Solar System are nearly coplanar to the ecliptic, this occurs when the Sun, Earth, and the body are configured in an approximately straight line, or syzygy; that is, Earth and the body are in the same ...