Minor planet
[5][7] This terminology has become more complicated by the discovery of numerous minor planets beyond the orbit of Jupiter, especially trans-Neptunian objects that are generally not considered asteroids.
Objects are called dwarf planets if their own gravity is sufficient to achieve hydrostatic equilibrium and form an ellipsoidal shape.
After the observation arc is accurate enough to predict its future location, a minor planet is formally designated and receives a number.
Because modern discovery techniques are finding vast numbers of new asteroids, they are increasingly being left unnamed.
Commission 15[27] of the International Astronomical Union is dedicated to the Physical Study of Comets & Minor Planets.
[28] This includes standard asteroid physical characteristics such as the properties of binary systems, occultation timings and diameters, masses, densities, rotation periods, surface temperatures, albedoes, spin vectors, taxonomy, and absolute magnitudes and slopes.
This small change will be reflected in the periodic change of the planet's light curve, which can be observed by ground-based equipment, so as to obtain the planet's magnitude, rotation period, rotation axis orientation, shape, albedo distribution, and scattering properties.
[33] In addition, statistical analysis of impact craters is an important means of obtaining information on the age of a planet surface.
[34] In addition to impact, there are a variety of other rich geological effects on the surface of minor planets,[35] such as mass wasting on slopes and impact crater walls,[36] large-scale linear features associated with graben,[37] and electrostatic transport of dust.
[38] By analysing the various geological processes on the surface of minor planets, it is possible to learn about the possible internal activity at this stage and some of the key evolutionary information about the long-term interaction with the external environment, which may lead to some indication of the nature of the parent body's origin.
Compared to other atmosphere-free bodies in the solar system (e.g. the Moon), minor planets have weaker gravity fields and are less capable of retaining fine-grained material, resulting in a somewhat larger surface soil layer size.
[40] For some small planets, their surfaces are more exposed as boulders of varying sizes, up to 100 metres in diameter, due to their weaker gravitational pull.
[41] These boulders are of high scientific interest, as they may be either deeply buried material excavated by impact action or fragments of the planet's parent body that have survived.
Usually in the interior of the planet, the convection of the conductive fluid will generate a large and strong magnetic field.
