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Following Anaximander, his pupil Anaximenes (c. 585 – c. 528/4) held that the stars, Sun, Moon, and planets are all made of fire. But whilst the stars are fastened on a revolving crystal sphere like nails or studs, the Sun, Moon, and planets, and also the Earth, all just ride on air like leaves because of their breadth. [9]
Therefore, there must be fire at the center of the cosmos. [6] According to Philolaus, the central fire and cosmos are surrounded by an unlimited expanse. Three unlimited elements: time, breath, and void, were drawn in toward the central fire, where the interaction between fire and breath created the elements of earth and water.
Representative lifetimes of stars as a function of their masses The change in size with time of a Sun-like star Artist's depiction of the life cycle of a Sun-like star, starting as a main-sequence star at lower left then expanding through the subgiant and giant phases, until its outer envelope is expelled to form a planetary nebula at upper right Chart of stellar evolution
The Sun is the star at the center of the Solar System.It is a massive, nearly perfect sphere of hot plasma, heated to incandescence by nuclear fusion reactions in its core, radiating the energy from its surface mainly as visible light and infrared radiation with 10% at ultraviolet energies.
Astrophysical plasmas are also observed in accretion disks around stars or compact objects like white dwarfs, neutron stars, or black holes in close binary star systems. [45] Plasma is associated with ejection of material in astrophysical jets , which have been observed with accreting black holes [ 46 ] or in active galaxies like M87's jet that ...
A star is a luminous spheroid of plasma held together by self-gravity. [1] The nearest star to Earth is the Sun.Many other stars are visible to the naked eye at night; their immense distances from Earth make them appear as fixed points of light.
Aristotle added a fifth element, aether (αἰθήρ aither), as the quintessence, reasoning that whereas fire, earth, air, and water were earthly and corruptible, since no changes had been perceived in the heavenly regions, the stars cannot be made out of any of the four elements but must be made of a different, unchangeable, heavenly ...
A different tradition makes an analogy between the creation of the firmament and the curdling of milk into cheese. Another tradition is that a combination of fire and water makes up the heavens. This is somewhat similar to a view attributed to Anaximander, whereby the firmament is made of a mixture of hot and cold (or fire and moisture). [39]