Objects sol.odt







Objects between ≈400 and ≈200 km in radius [ edit ]
Most objects in this size range are expected to be round. All the satellites except Proteus are round. The asteroid 10 Hygiea is not, and 2 Pallasand 4 Vesta are borderline. Like the satellites, TNOs in this size range are expected to be round (assuming the estimated size is correct).

Selected objects between 200 and 100 km in radius [ edit ]
 Objects between 200 and 100 km in radius (400 and 200 km in diameter). The largest of these may lie above the boundary for hydrostatic equilibrium, but most are irregular. Most of the trans-Neptunian objects listed with a radius smaller than 200 km have "assumed sizes based on a generic albedo of 0.09" since they are too far away to directly measure their sizes with existing instruments. Values relative to Earth are not included beyond this point. Mass switches from 1021 kg to 1018 kg (Zg). Main-belt asteroids have orbital elements constrained by (2.0 AU < a < 3.2 AU; q > 1.666 AU) according to JPL Solar System Dynamics (JPLSSD).[30] This is not complete, missing many poorly known TNOs.[20]

Selected objects between 100 and 50 km in radius [ edit ]
 Objects 100 and 50 km in radius (200 km to 100 km in average diameter). The listed objects currently include most objects in the asteroid belt and moons of the gas giants in this size range, but many newly discovered objects in the outer Solar System are missing, such as those included in the following reference.[20] Asteroid spectral types are mostly Tholen, but some might be SMASS.

Examples of objects between 50 km and 20 km in radius [ edit ]
There are easily tens of thousands of objects 50 km in radius or smaller[clarification needed], but only a fraction have been explored. The number of digits is not an endorsement of significant figures. The table switches from ×1018 kg to ×1015 kg (Eg), and many of these mass values are assumed. (See also: List of minor planets.)

Examples of objects below 1 km (1000 m) in radius [ edit ]
 In the asteroid belt alone there are estimated to be between 1.1 and 1.9 million objects with a radius above 0.5 km,[64]many of which are in the range 0.5–1.0 km. Countless more have a radius below 0.5 km.

Very few objects in this size range have been explored or even imaged. The exceptions are objects that have been visited by a probe, or have passed close enough to Earth to be imaged. Radius is by mean geometric radius. Number of digits not an endorsement of significant figures. Mass scale shifts from × 1015 to 1012 kg, which is 1015 grams (Petagram - Pg). Currently most of the objects of mass between 109 kg to 1012 kg (less than 1000 teragrams (Tg)) listed here are near-Earth asteroids. (See also: List of NEAs by distance from Sun.) 1994 WR12 possesses less mass than the Great Pyramid of Giza, 5.9 × 109 kg.

For more about very small objects in the Solar System, see Meteoroid, Micrometeoroid, and Interplanetary dust cloud. (See also Visited/imagedbodies.)

Surface gravity[edit]
The surface gravity at the equator of a body can in most cases be accurately calculated using Newton's law of universal gravitation andcentrifugal force.

The gravitational acceleration at the equator is given by Newton's law of universal gravitation. The formula that follows from this law is: where
 * ag is the magnitude of the gravitational acceleration
 * G is the gravitational constant
 * m is the mass of the celestial body
 * r is the equatorial radius of the celestial body (if this varies significantly, the mean equatorial radius is used)

The magnitude of the outward acceleration due to centrifugal force is given by where
 * T is the rotation peri

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