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A chemical element, often simply called an element, is a type of atom which has a specific number of protons in its atomic nucleus (i.e., a specific atomic number, or Z). [1] The definitive visualisation of all 118 elements is the periodic table of the elements , whose history along the principles of the periodic law was one of the founding ...
Between then and around 1851, when the number of planets had reached 23, astronomers started using the word asteroid (from Greek, meaning 'star-like' or 'star-shaped') for the smaller bodies and began to distinguish them as minor planets rather than major planets.
The periodic table is a graphic description of the periodic law, which states that the properties and atomic structures of the chemical elements are a periodic function of their atomic number. Elements are placed in the periodic table according to their electron configurations , [41] the periodic recurrences of which explain the trends in ...
Stable even–even nuclides number as many as three isobars for some mass numbers, and up to seven isotopes for some atomic numbers. Conversely, of the 251 known stable nuclides, only five have both an odd number of protons and odd number of neutrons: hydrogen-2 ( deuterium ), lithium-6 , boron-10 , nitrogen-14 , and tantalum-180m .
720,000 km/h (450,000 mi/h) [10] Orbital period. ~230 million years [10] The Solar System [d] is the gravitationally bound system of the Sun and the objects that orbit it. [11] It was formed about 4.6 billion years ago when a dense region of a molecular cloud collapsed, forming the Sun and a protoplanetary disc.
Relative masses of the Solar planets. Jupiter at 71% of the total and Saturn at 21% dominate the system. Relative masses of the solid bodies of the Solar System. Earth at 48% and Venus at 39% dominate. Bodies less massive than Pluto are not visible at this scale. Relative masses of the rounded moons of the Solar System.
The number of dwarf planets in the Solar System is unknown. Estimates have run as high as 200 in the Kuiper belt and over 10,000 in the region beyond. 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 bodies ...
Nearly 97.5% of all minor planets are main-belt asteroids (MBA), while Jupiter trojans, Mars-crossing and near-Earth asteroids each account for less than 1% of the overall population. Only a small number of distant minor planets, that is the centaurs and trans-Neptunian objects, have been numbered so far. In the partial lists, table column ...