Sun:

Introduction:

The star at the center of the Solar System is the Sun. Its core undergoes nuclear fusion events, transforming it into a nearly perfect ball of hot plasma that is incandescent. The Sun is the most significant source of energy for life on Earth, radiating this energy mostly as light, ultraviolet, and infrared radiation.

 

Sun

The Sun's radius is around 109 times greater than that of the Earth at 695,000 kilometers (432,000 miles). Its mass is approximately 330,000 times that of the Earth and accounts for 99.86% of the solar system's total mass.  About 73% of the mass of the Sun is made up of hydrogen; the remaining 25% is largely helium, with much lesser amounts of heavier elements including oxygen, carbon, neon, and iron.

 

A G-type main-sequence star, the Sun (G2V). Consequently, it is described to informally and inaccurately as a yellow dwarf (its light is actually white). It was created around 4.6 billion years ago when a portion of a massive molecular cloud gravitationally collapsed. The majority of this material gravitated toward the center, while the remainder flattened into the Solar System's circling disk. The central mass eventually started nuclear fusion in its core as a result of becoming so hot and dense. This mechanism is assumed to be the primary way that stars develop.

 

About 600 million tons of hydrogen are fused into helium in the Sun's core every second, creating 4 million tons of energy out of the process. The Sun's light and heat are produced by this energy, which can take anywhere between 10,000 and 170,000 years to escape the core. The Sun will eventually change into a red giant when hydrogen fusion in its core has decreased to the extent that it is no longer in hydrostatic equilibrium, causing its core to experience a notable increase in density and warmth as its outer layers expand. It is predicted that, after five billion years, the Sun would grow big enough to engulf Mercury and Venus in their current orbits and make Earth inhabitable.After that, it will shed its outer layers and transform into a white dwarf, a dense type of cooling star that no longer produces energy through fusion but continues to shine and emit heat from its prior fusion.

 

Since ancient times, people have understood how much of an impact the Sun has on the planet. Some cultures saw the Sun as a divinity. Some solar calendars are based on the synodic rotation of Earth and its orbit around the Sun. The Gregorian calendar, which is the most widely used calendar today, is based on the common 16th-century understanding that the Sun actually moves as observed.

 

Sun

Characteristics:

A G-type main-sequence star, the Sun accounts for 99.86% of the solar system's mass. With an absolute magnitude of 4.83, the Sun is predicted to be brighter than 85% of the Milky Way's stars, the majority of which are red dwarfs. Population I, or a star rich in heavy elements, is what the Sun is. The shockwaves from one or more neighboring supernovae may have served as the catalyst for the Sun's development. In contrast to the abundances of these elements in so-called Population II, heavy-element-poor stars, the Solar System has a large abundance of heavy elements like gold and uranium.The production of the heavy elements most likely occurred during endothermic nuclear processes during a supernova or through neutron absorption inside a huge second-generation star.

 

With an apparent magnitude of 26.74, the Sun is by far the brightest object in the sky over the planet. The next brightest star, Sirius, is nearly 13 billion times fainter than this one, with an apparent magnitude of 1.46. The mean distance from the Sun's center to the Earth's center is measured in astronomical units (approximately 150,000,000 km; 93,000,000 mi), while the distance fluctuates as Earth moves from perihelion in January to aphelion in July.The extreme values can range from 147,083,346 km to 152,112,126 km, while the distances can range from 147,098,074 km (perihelion) to 152,097,701 km (aphelion). Light from the Sun's horizon to Earth's horizon travels at its average distance in roughly 8 minutes and 20 seconds, while light from the Sun and Earth's nearest points travels at its average distance in about two seconds slower. Through photosynthesis, this sunlight's energy sustains practically all life on Earth and regulates the planet's climate and weather.

 

The density of the Sun falls exponentially with height above the photosphere but it lacks distinct boundaries.The distance from the Sun's center to its photosphere, or apparent visible surface, is used to determine the radius of the Sun for measuring purposes. According to this standard, the Sun is a nearly perfect sphere with an estimated oblateness of 9 millionths, meaning that the distance between its polar and equatorial diameters is only 10 kilometers (6.2 mi). The Sun's shape is not considerably impacted by the planets' mild tidal influence.At its equator, the Sun rotates more quickly than at its poles. Convective motion resulting from heat transfer and the Coriolis force resulting from the Sun's rotation are both responsible for this differential rotation. The rotating period is roughly 25.6 days at the equator and 33.5 days at the poles in a celestial frame of reference. The apparent rotational period of the Sun near its equator, as seen from Earth as it revolves around the Sun, is roughly 28 days. The Sun turns counterclockwise around its axis of rotation when viewed from a location above its north pole. At its equator, the Sun rotates more quickly than at its poles.

 

Motion in Solar System:

Eight planets are known to be revolving around the Sun. Mercury, Venus, Earth, and Mars are among the four terrestrial planets, along with two gas giants (Jupiter and Saturn) and two ice giants (Uranus and Neptune). The Solar System also contains nine objects that are typically regarded as dwarf planets and a few more contenders, as well as an asteroid belt, several comets, and a significant number of frozen objects that are located beyond of Neptune's orbit. Numerous smaller things, including six of the planets, also have natural satellites of their own; in example, the satellite systems of Jupiter, Saturn, and Uranus resemble miniature replicas of the solar system in certain aspects.

 

The gravitational force of the planets causes the Sun to move. The Sun's center is always 2.2 solar radii away from the barycenter. Jupiter, Saturn, Uranus, and Neptune are primarily to blame for the Sun's motion. The motion forms a trefoil pattern during some periods of several decades, but between these periods it appears more erratic. The pattern essentially repeats itself after 179 years (nine times the synodic period of Jupiter and Saturn), but rotated by around 24°.The same gravitational forces equally distort the orbits of the inner planets, including the Earth. As a result, the Sun's motion has minimal bearing on the relative positions of the Earth and the Sun or the solar irradiance on the Earth as a function of time.

 

Viewing With The Eyes:

While staring at the Sun with the naked eye can hurt, doing so for brief periods is safe for eyes that are normally thin and undilated. Sungazing is the practice of staring directly at the Sun and results in phosphene visual artifacts and momentary partial blindness. Additionally, the retina receives roughly 4 milliwatts of sunshine, which slightly warms it and may harm eyes that are unable to adjust to the brightness. A 100-second exposure to the direct Sun with the naked eye can start to result in UV-induced, sunburn-like lesions on the retina. This is especially true when the UV light from the Sun is strong and well focused.

 

Without a suitable filter that blocks UV and significantly reduces the sunlight, viewing the Sun through light-concentrating optics like binoculars could permanently harm the retina. The viewer is advised to use a filter made for that purpose while using an attenuating filter to observe the Sun. At high light levels, certain homemade filters that let through UV or IR rays can actually cause eye damage. Even fleeting glimpses through an unfiltered telescope at the midday Sun can have lasting effects.

 

Rayleigh scattering and Mie scattering from a particularly long journey through Earth's atmosphere attenuate sunlight at sunrise and sunset, making the Sun occasionally pale enough to be comfortably observed with the unaided eye or securely observed through optics (provided there is no risk of bright sunlight suddenly appearing through a break between clouds). This atmospheric attenuation is influenced by hazy circumstances, air dust, and excessive humidity.

 

Sometimes, just after dusk or before dawn, a green flash, an optical phenomena, can be seen. The flash is brought on by the Sun's light being bent toward the observer just below the horizon (often through a temperature inversion). Light with shorter wavelengths, like violet, blue, and green, is bent more than light with longer wavelengths, like yellow, orange, and red, but violet and blue light scatter more, leaving light that appears green.