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Herschel underestimated its diameter at 260 km (160 mi) in 1802; in 1811, German astronomer Johann Hieronymus Schröter overestimated it as 2,613 km (1,624 mi). [25] In the 1970s, infrared photometry enabled more accurate measurements of its albedo, and Ceres's diameter was determined to within ten per cent of its true value of 939 km (583 mi).
At a diameter of 964 km, Ceres is the largest object in ... it is only 28% the size of Earth's Moon and 41% ... Ceres orbits the Sun at a mean distance of 2.77 ...
This list contains a selection of objects 50 and 99 km in radius (100 km to 199 km in average diameter). The listed objects currently include most objects in the asteroid belt and moons of the giant planets in this size range, but many newly discovered objects in the outer Solar System are missing, such as those included in the following ...
The total mass of the asteroid belt is estimated to be 3% that of the Moon. [2] Ceres, ... a distance of 2.7 AU from the ... 200 m and 10 km in diameter are ...
The smallest natural satellite that is gravitationally rounded is Saturn I Mimas (radius 198.2 ± 0.4 km). This is smaller than the largest natural satellite that is known not to be gravitationally rounded, Neptune VIII Proteus (radius 210 ± 7 km).
At 513 ± 3 km in diameter, [9] Pallas is slightly smaller than Vesta (525.4 ± 0.2 km [48]). The mass of Pallas is 79% ± 1% that of Vesta, 22% that of Ceres, and a quarter of one percent that of the Moon. Pallas is farther from Earth and has a much lower albedo than Vesta, and hence is dimmer as seen from Earth.
At the time Makemake and Haumea were named, it was thought that trans-Neptunian objects (TNOs) with icy cores would require a diameter of only about 400 km (250 mi), or 3% the size of Earth – the size of the moons Mimas, the smallest moon that is round, and Proteus, the largest that is not – to relax into gravitational equilibrium. [65]
The Moon is Earth's only natural satellite.It orbits at an average distance of 384,400 km (238,900 mi), about 30 times the diameter of Earth. Tidal forces between Earth and the Moon have synchronized the Moon's orbital period (lunar month) with its rotation period at 29.5 Earth days, causing the same side of the Moon to always face Earth.