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The superior planets, orbiting outside the Earth's orbit, do not exhibit a full range of phases since their maximum phase angles are smaller than 90°. Mars often appears significantly gibbous, it has a maximum phase angle of 45°. Jupiter has a maximum phase angle of 11.1° and Saturn of 6°, [1] so their phases are almost always full.
The phase curve of the Moon [26] compared to Mercury. [1] The phase curve of the Moon approximately resembles that of Mercury due to the similarities of the surfaces and the lack of an atmosphere on either body. [27] Clementine spacecraft data analyzed by J. Hillier, B. Buratti and K. Hill [28] indicate a lunar opposition surge.
Diagram showing the eastern and western quadratures of a superior planet like Mars. 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.
"Inferior planet" refers to Mercury and Venus, which are closer to the Sun than Earth is. "Superior planet" refers to Mars, Jupiter, Saturn, Uranus, and Neptune (the latter two added later), which are further from the Sun than Earth is. The terms are sometimes used more generally; for example, Earth is an inferior planet relative to Mars.
For some objects, such as the Moon (see lunar phases), Venus and Mercury the phase angle (as seen from the Earth) covers the full 0–180° range. The superior planets cover shorter ranges. For example, for Mars the maximum phase angle is about 45°. For Jupiter, the maximum is 11.1° and for Saturn 6°. [1]
Visual conjunction between the Moon and the planet Venus, the two brightest objects in the night sky. In astronomy, a conjunction occurs when two astronomical objects or spacecraft appear to be close to each other in the sky. This means they have either the same right ascension or the same ecliptic longitude, usually as observed from Earth. [1] [2]
51 Pegasi b, officially named Dimidium / d ɪ ˈ m ɪ d i ə m /, is an extrasolar planet approximately 50 light-years (15 parsecs) away in the constellation of Pegasus.It was the first exoplanet to be discovered orbiting a main-sequence star, [3] the Sun-like 51 Pegasi, and marked a breakthrough in astronomical research.
Similar results have been obtained for NGC 6530, IC 5146, and NGC 6611. [1] The numbered curves show the Hayashi tracks of stars of that mass (in solar masses). The small circles represent observational data of T Tauri stars. The bold curve to the right is the birthline, above which few stars exist.