https://en.wikipedia.org/wiki/Sun
The Sun is the star at the center of the Solar System. It is a massive, hot ball of plasma, inflated and heated by energy produced by nuclear fusion reactions at its core. Part of this energy is emitted from its surface as visible light, ultraviolet, and infrared radiation, providing most of the energy for life on Earth. The Sun has been an object of veneration in many cultures. It has been a central subject for astronomical research since antiquity.
The Sun orbits the Galactic Center at a distance of 24,000 to 28,000 light-years.[9] From Earth, it is on average 1 AU (1.496×108 km) or about 8 light-minutes away. Its diameter is about 1,391,400 km(864,600 mi; 4.64 LS), 109 times that of Earth. Its mass is about 330,000 times that of Earth, making up about 99.86% of the total mass of the Solar System.[18] Roughly three-quarters of the Sun's mass consists of hydrogen (~73%); the rest is mostly helium (~25%), with much smaller quantities of heavier elements, including oxygen, carbon, neon, and iron.[19]
The Sun is a G-type main-sequence star (G2V), informally called a yellow dwarf, though its light is actually white. It formed approximately 4.6 billion[a][14][20] years ago from the gravitational collapseof matter within a region of a large molecular cloud. Most of this matter gathered in the center, whereas the rest flattened into an orbiting disk that became the Solar System. The central mass became so hot and dense that it eventually initiated nuclear fusion in its core. It is thought that almost all stars form by this process.
Every second, the Sun's core fuses about 600 million tons of hydrogen into helium and converts 4 million tons of matter into energy. Far in the future, when hydrogen fusion in the Sun's core diminishes to the point where the Sun is no longer in hydrostatic equilibrium, its core will undergo a marked increase in density and temperature which will cause its outer layers to expand, eventually transforming the Sun into a red giant. This process will make the Sun large enough to render Earth uninhabitable approximately five billion years from the present. Subsequently, the Sun will shed its outer layers and become a dense type of cooling star (a white dwarf), and no longer produce energy by fusion, but it will still glow and give off heat from its previous fusion for trillions of years. After that it is theorized to become a super dense black dwarf, giving off no more energy.
意思是說，宇宙意外，太陽意外，地球意外，生命意外，演化意外，人生蜉蝣，卻貪嗔痴，造作不休，樂此不疲，但爭朝夕，所謂荒謬，莫過于此，
Astronomical unit
The astronomical unit (symbol: au,[1][2][3][4] or AU) is a unit of length defined to be exactly equal to 149,597,870,700 m.[5] Historically, the astronomical unit was originally conceived as the average Earth-Sun distance (the average of Earth's aphelion and perihelion), before its modern redefinition in 2012.
The astronomical unit is used primarily for measuring distances within the Solar System or around other stars. It is also a fundamental component in the definition of another unit of astronomical length, the parsec.[6] One au is equivalent to 499 light-seconds to within 10 parts per million.
