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The timeline of discovery of Solar System planets and their natural satellites charts the progress of the discovery of new bodies over history. Each object is listed in chronological order of its discovery (multiple dates occur when the moments of imaging, observation, and publication differ), identified through its various designations (including temporary and permanent schemes), and the ...
1501 – Indian astronomer Nilakantha Somayaji proposes a universe in which the planets orbit the Sun, but the Sun orbits the Earth. [64] c. 1514 – Nicolaus Copernicus states his heliocentric theory in Commentariolus. [65] [66] [67] 1522 – First circumnavigation of the world by Magellan-Elcano expedition shows that the Earth is, in effect ...
c. 16th century BCE – Mesopotamian cosmology has a flat, circular Earth enclosed in a cosmic ocean. [1]c. 15th–11th century BCE – The Rigveda of Hinduism has some cosmological hymns, particularly in the late book 10, notably the Nasadiya Sukta which describes the origin of the universe, originating from the monistic Hiranyagarbha or "Golden Egg".
Italian polymath Galileo Galilei was an early user and made prolific discoveries, including the phases of Venus, which definitively disproved the arrangement of spheres in the Ptolemaic system. Galileo also discovered that the Moon was cratered, that the Sun was marked with sunspots, and that Jupiter had four satellites in orbit around it. [13]
The universe has appeared much the same as it does now, for many billions of years. It will continue to look similar for many more billions of years into the future. The galactic disk of the Milky Way is estimated to have been formed 8.8 ± 1.7 billion years ago but only the age of the Sun, 4.567 billion years, is known precisely. [82]
The Sun is about halfway through its main-sequence stage, during which nuclear fusion reactions in its core fuse hydrogen into helium. Each second, more than four billion kilograms of matter are converted into energy within the Sun's core, producing neutrinos and solar radiation. At this rate, the Sun has so far converted around 100 times the ...
Researchers estimate that it could contain somewhere between 1,000 and 10,000 trillion stars.
The Sun was found to be part of a galaxy made up of more than 10 10 stars (10 billion stars). The existence of other galaxies, one of the matters of the great debate , was settled by Edwin Hubble , who identified the Andromeda nebula as a different galaxy, and many others at large distances and receding, moving away from our galaxy.