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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.
The Solar System is located within a structure called the Local Bubble, a low-density region of the galactic interstellar medium. [5] Within this region is the Local Interstellar Cloud (LIC), an area of slightly higher hydrogen density. It is estimated that the Solar System entered the LIC within the past 10,000 years. [6]
The diffuse photoionized gas contains filaments of higher density, about one atom per cubic meter, [145] which is 5–200 times the average density of the universe [146]. The IGM is inferred to be mostly primordial in composition, with 76% hydrogen by mass, and enriched with higher mass elements from high-velocity galactic outflows. [147]
Astronomers have discovered what may be the brightest object in the universe, a quasar with a black hole at its heart growing so fast that it swallows the equivalent of a sun a day.
The solar wind plasma which is moving roughly "upstream" (in the same direction as the Sun's motion through the galaxy) is compressed into a nearly-spherical form, whereas the plasma moving "downstream" (opposite the Sun's motion) flows out for a much greater distance before giving way to the ISM, defining the long, trailing shape of the heliotail.
If the Sun–Neptune distance is scaled to 100 metres (330 ft), then the Sun would be about 3 cm (1.2 in) in diameter (roughly two-thirds the diameter of a golf ball), the giant planets would be all smaller than about 3 mm (0.12 in), and Earth's diameter along with that of the other terrestrial planets would be smaller than a flea (0.3 mm or 0. ...
After about 9.8 billion years, the universe had expanded sufficiently so that the density of matter was less than the density of dark energy, marking the beginning of the present dark-energy-dominated era. [45] In this era, the expansion of the universe is accelerating due to dark energy.
It is a gas giant with a mass more than 2.5 times that of all the other planets in the Solar System combined and slightly less than one-thousandth the mass of the Sun. Its diameter is eleven times that of Earth , and a tenth that of the Sun. Jupiter orbits the Sun at a distance of 5.20 AU (778.5 Gm ), with an orbital period of 11.86 years .