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The SOHO (ESA & NASA) joint project implies that all materials created by its probe are copyrighted and require permission for commercial non-educational use. Images featured on the Astronomy Picture of the Day (APOD) web site may be copyrighted. The National Space Science Data Center (NSSDC) site has been known to host copyrighted content.
Callisto (/ k ə ˈ l ɪ s t oʊ / kə-LIST-oh), or Jupiter IV, is the second-largest moon of Jupiter, after Ganymede.In the Solar System it is the third-largest moon after Ganymede and Saturn's largest moon Titan, and nearly as large as the smallest planet Mercury.
The largest, Ganymede, is the largest moon in the Solar System and surpasses the planet Mercury in size (though not mass). Callisto is only slightly smaller than Mercury in size; the smaller ones, Io and Europa, are about the size of the Moon. The three inner moons — Io, Europa, and Ganymede — are in a 4:2:1 orbital resonance with each other.
Planetary-mass satellites larger than Pluto, the largest Solar dwarf planet. The three largest satellites Ganymede, Titan, and Callisto are of similar size or larger than the planet Mercury; these and four more – Io, the Moon, Europa, and Triton – are larger and more massive than the largest and most massive dwarf planets, Pluto and Eris.
The distinction between a satellite and a classical planet was not recognized until after the heliocentric model of the Solar System was established. When in 1610 Galileo discovered the first satellites of another planet (the four Galilean moons of Jupiter), he referred to them as "four planets flying around the star of Jupiter at unequal intervals and periods with wonderful swiftness."
Size comparison of Earth and the Moon There is no established lower limit on what is considered a "moon". Every natural celestial body with an identified orbit around a planet of the Solar System , some as small as a kilometer across, has been considered a moon, though objects a tenth that size within Saturn's rings, which have not been ...
The size of solid bodies does not include an object's atmosphere. For example, Titan looks bigger than Ganymede, but its solid body is smaller. For the giant planets , the "radius" is defined as the distance from the center at which the atmosphere reaches 1 bar of atmospheric pressure.
The actual Hill radius for the Earth-Moon pair is on the order of 60,000 km (i.e., extending less than one-sixth the distance of the 378,000 km between the Moon and the Earth). [9] In the Earth-Sun example, the Earth (5.97 × 10 24 kg) orbits the Sun (1.99 × 10 30 kg) at a distance of 149.6 million km, or one astronomical unit (AU). The Hill ...