Belt located between 2.12 and 3.3 The astronomical unit for length is described as the "mean" distance (average of aphelion and perihelion distances) between the Earth and the Sun. Though most references state the value for 1 AU to be approximately 150 million kilometers, the currently accepted precise value for the AU is 149,597,870.66 km. The from the Our parent star. The structure of Sun's interior is the result of the hydrostatic equilibrium between gravity and the pressure of the gas. The interior consists of three shells: the core, radiative region, and convective region. Image source: http://eclipse99.nasa.gov/pages/SunActiv.html. The core is the hot, dense central region in which the and located between the orbits of Mars and Jupiter containing the vast majority of asteroids. The asteroid belt is also termed the main asteroid belt or main belt to distinguish it from other asteroid populations in the The Sun and set of objects orbiting around it including planets and their moons and rings, asteroids, comets, and meteoroids. such as near-Earth asteroids and the Trojan asteroids that share the same The elliptical path of one body around another, typically the path of a small body around a much larger body. However, depending on the mass distribution of the objects, they may rotate around an empty spot in space • The Moon orbits around the Earth. • The Earth orbits around as Jupiter. The asteroid belt is however very sparsely populated and the distribution of asteroids within it is not uniform. The destruction of larger bodies yields families of asteroids which share very similar orbital properties and cluster together. There are zones in which almost no asteroids occur. These sparsely populated zones are Lack of asteroids in regions within the asteroid belt (between Mars and Jupiter) coinciding with orbital periods that are simple fractions of Jupiter’s own orbital period. The absence of asteroids in these gaps is due to resonance with Jupiter’s gravitational influence. and result from orbital resonances with Jupiter. The main asteroid belt is a leftover from the early Solar Definable part of the universe that can be open, closed, or isolated. An open system exchanges both matter and energy with its surroundings. A closed system can only exchange energy with its surroundings; it has walls through which heat can pass. An isolated system cannot exchange energy or matter with when the strong gravitational influence of Jupiter prevented the Hypothetical solid celestial body that accumulated during the last stages of accretion. These bodies, from ~1-100 km in size, formed in the early solar system by accretion of dust (rock) and ice (if present) in the central plane of the solar nebula. Most planetesimals accreted to planets, but many – in this region from coalescing to form a planetary In the context of planetary formation, the core is the central region of a large differentiated asteroid, planet or moon and made up of denser materials than the surrounding mantle and crust. For example, the cores of the Earth, the terrestrial planets and differentiated asteroids are rich in metallic iron-nickel..
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