The Sun is the star at the center of the Solar System. The Earth and other matter (including other planets, asteroids, meteoroids, comets, and dust) orbit the Sun, which by itself accounts for about 99.86% of the Solar System's mass. [10] The mean distance of the Sun from the Earth is approximately 149.6 million kilometers (1 AU), and its light travels this distance in 8 minutes and 19 seconds. This distance varies throughout the year from a minimum of 147.1 million kilometers (0.9833 AU) on the perihelion (around 3 January), to a maximum of 152.1 million kilometers (1.017 AU) on the aphelion (around 4 July). [11] Energy from the Sun, in the form of sunlight, supports almost all life on Earth via photosynthesis, [12] and drives the Earth's climate and weather. The Sun consists of hydrogen (about 74% of its mass, or 92% of its volume), helium (about 24% of mass, 7% of volume), and trace quantities of other elements, including iron, nickel, oxygen, silicon, sulfur, magnesium, carbon, neon, calcium, and chromium. [13] The Sun has a spectral class of G2V. G2[14] The Sun's spectrum contains lines of ionized and neutral metals as well as very weak hydrogen lines. The V (Roman five) in the spectral class indicates that the Sun, like most stars, is a main sequence star. This means that it generates its energy by nuclear fusion of hydrogen nuclei[15] [16] means that it has a surface temperature of approximately 5,780 K (5,510 °C) giving it a white color, which often appears as yellow when seen from the surface of the Earth because of atmospheric scattering. It is this scattering of light at the blue end of the spectrum that gives the surrounding sky its color. into helium. There are more than 100 million G2 class stars in our galaxy. Once regarded as a small and relatively insignificant star, the Sun is now presumed to be brighter than 85% of the stars in the galaxy, most of which are red dwarfs.
The Sun's hot corona continuously expands in space creating the solar wind, a hypersonic stream of charged particles that extends to the heliopause at roughly 100 AU. The bubble in the interstellar medium formed by the solar wind, the heliosphere, is the largest continuous structure in the Solar System.[17] [18]
The Sun is currently traveling through the Local Interstellar Cloud in the low-density Local Bubble zone of diffuse high-temperature gas, in the inner rim of the Orion Arm of the Milky Way Galaxy, between the larger Perseus and Sagittarius arms of the galaxy. Of the 50 nearest stellar systems×1014 km) from the Earth, the Sun ranks 4th [19] in mass. Slightly different values for the magnitude have been published, for example 4.85[20] and 4.81.[21] The Sun orbits the center of the Milky Way galaxy at a distance of approximately 24,000–26,000 light years from the galactic center, moving generally in the direction of Cygnus and completing one revolution in about 225–250 million years (one Galactic year). Its orbital speed was thought to be 220 ± 20, km/s but a new estimate gives 251 km/s. [22][23] Since our galaxy is moving with respect to the cosmic microwave background radiation (CMB) in the direction of Hydra with a speed of 550 km/s, the Sun's resultant velocity with respect to the CMB is about 370 km/s in the direction of Crater or Leo. [24] within 17 light-years (1.6
In days gone by there was a land where the nights were always dark, and the sky spread over it like a black cloth, for there the moon never rose, and no star shone in the obscurity. At the creation of the world, the light at night had been sufficient. Three young fellows once went out of this country on a travelling expedition, and arrived in another kingdom, where, in the evening when the sun had disappeared behind the mountains, a shining globe was placed on an oak-tree, which shed a soft light far and wide. By means of this, everything could very well be seen and distinguished, even though it was not so brilliant as the sun. The travellers stopped and asked a countryman who was driving past with his cart, what kind of a light that was. "That is the moon," answered he; "our mayor bought it for three thalers, and fastened it to the oak-tree. He has to pour oil into it daily, and to keep it clean, so that it may always burn clearly. He receives a thaler a week from us for doing it."
When the countryman had driven away, one of them said, "We could make some use of this lamp, we have an oak-tree at home, which is just as big as this, and we could hang it on that. What a pleasure it would be not to have to feel about at night in the darkness!" "I'll tell you what we'll do," said the second; "we will fetch a cart and horses and carry away the moon. The people here may buy themselves another." "I'm a good climber," said the third, "I will bring it down." The fourth brought a cart and horses, and the third climbed the tree, bored a hole in the moon, passed a rope through it, and let it down. When the shining ball lay in the cart, they covered it over with a cloth, that no one might observe the theft. They conveyed it safely into their own country, and placed it on a high oak. Old and young rejoiced, when the new lamp let its light shine over the whole land, and bed-rooms and sitting-rooms were filled with it. The dwarfs came forth from their caves in the rocks, and the tiny elves in their little red coats danced in rings on the meadows.
The four took care that the moon was provided with oil, cleaned the wick, and received their weekly thaler, but they became old men, and when one of them grew ill, and saw that he was about to die, he appointed that one quarter of the moon, should, as his property, be laid in the grave with him. When he died, the mayor climbed up the tree, and cut off a quarter with the hedge-shears, and this was placed in his coffin. The light of the moon decreased, but still not visibly. When the second died, the second quarter was buried with him, and the light diminished. It grew weaker still after the death of the third, who likewise took his part of it away with him; and when the fourth was borne to his grave, the old state of darkness recommenced, and whenever the people went out at night without their lanterns they knocked their heads together.
When, however, the pieces of the moon had united themselves together again in the world below, where darkness had always prevailed, it came to pass that the dead became restless and awoke from their sleep. They were astonished when they were able to see again; the moonlight was quite sufficient for them, for their eyes had become so weak that they could not have borne the brilliance of the sun. They rose up and were merry, and fell into their former ways of living. Some of them went to the play and to dance, others hastened to the public-houses, where they asked for wine, got drunk, brawled, quarreled, and at last took up cudgels, and belabored each other. The noise became greater and greater, and at last reached even to heaven.
Saint Peter who guards the gate of heaven thought the lower world had broken out in revolt and gathered together the heavenly troops, which are to drive back the Evil One when he and his associates storm the abode of the blessed. As these, however, did not come, he got on his horse and rode through the gate of heaven, down into the world below. There he reduced the dead to subjection, bade them lie down in their graves again, took the moon away with him, and hung it up in heaven.
