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Viewed from a vantage point above its north pole, the Sun rotates counterclockwise around its axis of spin. [d] [48] A survey of solar analogs suggest the early Sun was rotating up to ten times faster than it does today. This would have made the surface much more active, with greater X-ray and UV emission.
Thus, the Sun occupies 0.00001% (1 part in 10 7) of the volume of a sphere with a radius the size of Earth's orbit, whereas Earth's volume is roughly 1 millionth (10 −6) that of the Sun. Jupiter, the largest planet, is 5.2 AU from the Sun and has a radius of 71,000 km (0.00047 AU; 44,000 mi), whereas the most distant planet, Neptune, is 30 AU ...
The core of the Sun is considered to extend from the center to about 0.2 of the solar radius (139,000 km; 86,000 mi). [1] It is the hottest part of the Sun and of the Solar System . It has a density of 150,000 kg/m 3 (150 g/cm 3 ) at the center, and a temperature of 15 million kelvins (15 million degrees Celsius; 27 million degrees Fahrenheit).
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]
Another example is Earth's axial tilt, which, due to friction raised within Earth's mantle by tidal interactions with the Moon , is incomputable from some point between 1.5 and 4.5 billion years from now. [104] The outer planets' orbits are chaotic over longer timescales, with a Lyapunov time in the range of 2–230 million years. [105]
The Sun has also undergone periodic changes in luminosity that can have a significant impact on the Earth. [107] The Maunder minimum, for example, is believed to have caused the Little Ice Age phenomenon during the Middle Ages. [108] At the center of the Sun is the core region, a volume of sufficient temperature and pressure for nuclear fusion ...
Image credits: Sasha Weilbaker #4 Wind Blades. Humpback Whales are one of the largest weighing animals of the world, yet they are profound swimmers, which attributes down to its flippers (fins).
It offered explanations for a variety of properties of the Solar System, including the nearly circular and coplanar orbits of the planets, and their motion in the same direction as the Sun's rotation. Some elements of the original nebular theory are echoed in modern theories of planetary formation, but most elements have been superseded.