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According to the IAU's explicit count, there are eight planets in the Solar System; four terrestrial planets (Mercury, Venus, Earth, and Mars) and four giant planets, which can be divided further into two gas giants (Jupiter and Saturn) and two ice giants (Uranus and Neptune). When excluding the Sun, the four giant planets account for more than ...
Also, these stars have high UV radiation and winds that could photoevaporate the gas in the disk, leaving just the heavy elements. [62] For comparison, Neptune's mass equals 17 Earth masses, Jupiter has 318 Earth masses, and the 13-Jupiter-mass limit used in the IAU's working definition of an exoplanet equals approximately 4000 Earth masses. [62]
Neptune's mass of 1.0243 × 10 26 kg [8] is intermediate between Earth and the larger gas giants: it is 17 times that of Earth but just 1/19th that of Jupiter. [g] Its gravity at 1 bar is 11.15 m/s 2, 1.14 times the surface gravity of Earth, [71] and surpassed only by Jupiter. [72] Neptune's equatorial radius of 24,764 km [11] is nearly four ...
Sudarsky's classification of gas giants for the purpose of predicting their appearance based on their temperature was outlined by David Sudarsky and colleagues in the paper Albedo and Reflection Spectra of Extrasolar Giant Planets [1] and expanded on in Theoretical Spectra and Atmospheres of Extrasolar Giant Planets, [2] published before any successful direct or indirect observation of an ...
The term gas giant was coined in 1952 by the science fiction writer James Blish [6] and was originally used to refer to all giant planets.It is, arguably, something of a misnomer because throughout most of the volume of all giant planets, the pressure is so high that matter is not in gaseous form. [7]
Vega b, reported in 2021, is a candidate ultra-hot Neptune with a mass of ≥21.9 M E that revolves around Vega every 2.43 days, a mere 0.04555 AU (6,814,000 km) from its luminous host star. The equilbrium temperature of the planet is a white-hot 3,250 K (2,980 °C; 5,390 °F) assuming a Bond albedo of 0.25, which, if confirmed, would make it ...
The physical properties can influence the atmosphere significantly. A low surface gravity of low-mass brown dwarfs or planetary-mass objects can bring the atmosphere in a chemical disequilibrium. [49] Metallicity can influence the amount of methane in the atmosphere and in the extreme case of WISEA 1810−1010 the methane feature is undetectable.
[4] [5] The weight assigned to each property, , are free parameters that can be chosen to emphasize certain characteristics over others or to obtain desired index thresholds or rankings. The webpage also ranks what it describes as the habitability of planets and moons according to three criteria: the location in the habitable zone, ESI, and a ...