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In 2004, the discoverers placed an upper limit of 1,800 km on its diameter; [45] after observations by the Spitzer Space Telescope, this was revised downward by 2007 to less than 1,600 km. [46] In 2012, measurements from the Herschel Space Observatory suggested that Sedna's diameter was 995 ± 80 km, which would make it smaller than Pluto's ...
[9] [19] It was initially estimated to be 300 km (190 mi) in diameter under the assumption of an albedo of 0.15, [5] though observations of a single-chord stellar occultation at Penticton, Canada on 20 October 2018 suggested a smaller diameter of 220 km (140 mi), corresponding to a higher albedo of 0.21.
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 ...
Denis Moskowitz, a software engineer in Massachusetts, [94] proposed astronomical symbols for the dwarf planets Quaoar, Sedna, Orcus, Haumea, Eris, Makemake, and Gonggong. [ 95 ] [ 94 ] These symbols are somewhat standard among astrologers (e.g. in the program Astrolog ), [ 96 ] which is where planetary symbols are most used today.
Most named objects in this list have a diameter of 500 km or more. The Sun, a spectral class G2V main-sequence star; The inner Solar System and the terrestrial planets. 2021 PH27; Mercury. Mercury-crossing minor planets; Venus. Venus-crossing minor planets. 524522 Zoozve, Venus' quasi-satellite; Earth. Moon; Near-Earth asteroids (including ...
The number of dwarf planets in the Solar System is unknown. Estimates have run as high as 200 in the Kuiper belt [1] and over 10,000 in the region beyond. [2] However, consideration of the surprisingly low densities of many large trans-Neptunian objects, as well as spectroscopic analysis of their surfaces, suggests that the number of dwarf planets may be much lower, perhaps only nine among ...
The sednoids' orbits cannot be explained by perturbations from the giant planets, [9] nor by interaction with the galactic tides. [4] If they formed in their current locations, their orbits must originally have been circular; otherwise accretion (the coalescence of smaller bodies into larger ones) would not have been possible because the large relative velocities between planetesimals would ...
Hence, assuming equal albedos, it has a diameter of 286 ± 24 km [12] According to the estimate from 2017 based on an improved modelling, the size of Actaea is slightly larger at 290 ± 21 km. [ 6 ] Actaea has the same color as Salacia (V−I = 0.89 ± 0.02 and 0.87 ± 0.01 , respectively), supporting the assumption of equal albedos.