Solar System:

Introduction:

The gravitationally bound system comprising the Sun and the asteroids that orbit it is known as the Solar System. A massive interstellar molecular cloud gravitationally collapsed to make it 4.6 billion years ago. The Sun contains 99.86% of the system's mass, with Jupiter holding the majority of the remaining mass. Mercury, Venus, Earth, and Mars are the four terrestrial planets in the inner solar system, and they are made mostly of rock and metal.The four enormous planets in the outer solar system dwarf the terrestrial planets in both size and mass. The next two, Uranus and Neptune, are ice giants, being primarily composed of volatile substances with relatively high melting points compared to hydrogen and helium, such as water, ammonia, and methane. Jupiter and Saturn, the two largest, are gas giants, being primarily composed of hydrogen and helium. All eight planets have approximately circular orbits that are located close to the ecliptic, the plane of Earth's orbit.

 

Solar System

Numerous tiny worlds in the Solar System are orbiting the Sun, including numerous dwarf planets and innumerable minor bodies. [d] Many of the smaller worlds, including the six largest dwarf planets and the six major planets, are orbited by natural satellites, also known as "moons" after the Moon. Mercury, the smallest planet on Earth, is larger but not more massive than two natural satellites: Jupiter's moon Ganymede and Saturn's moon Titan. Jupiter's moon Callisto is also quite enormous. A ring of ice, dust, and moonlets surrounds each of the large planets, as well as some of the smaller bodies. Between the orbits of Mars and Jupiter is the asteroid belt, which is home to space debris made of ice, rock, and metal.The Kuiper belt and dispersed disc, which are populations of objects primarily made of ice and rock, are located beyond Neptune's orbit.

 

Detached objects are a subclass of minor planets found in the Solar System's outermost regions. How many of these items there will be is a topic of great discussion. These objects can be classified as dwarf planets since some of them are massive enough to have rounded due to their own gravity. The Kuiper belt objects Pluto, Orcus, Haumea, Quaoar, and Makemake, the scattered-disk objects Gonggong and Eris, and Sedna are all considered to be dwarf planets by astronomers. Comets, centaurs, and interplanetary dust storms are just a few of the different small-body populations that are free to move about the Solar System.

 

The heliosphere is an area of interplanetary medium in the interstellar medium formed by the solar wind, a stream of charged particles streaming outward from the Sun. The heliopause, which stretches out to the edge of the dispersed disc, is the region where the solar wind's pressure is equal to the interstellar medium's opposing pressure.It's possible that the Oort cloud, which is supposed to be the origin of long-period comets, is also out there, about a thousand times farther out than the heliosphere. The Milky Way galaxy's Orion Arm, which houses the majority of the stars that can be seen in the night sky, is 26,000 light-years away from the Solar System. The so-called Local Bubble contains the nearest stars, with Proxima Centauri being the closest at a distance of 4.2441 light-years.

 

Evolution and formation:

A huge molecular cloud's interior portion gravitationally collapsed to create the Solar System 4.568 billion years ago. This original cloud, which was probably many light-years broad and gave birth to many stars, was likely. This molecular cloud was composed primarily of hydrogen, with a minor quantity of helium and a few lighter elements that had been fused by earlier star generations, as is normal for molecular clouds. Conservation of angular momentum made the pre-solar nebula revolve faster as the region that would later form the Solar System compressed.The majority of the mass gathered in the centre, which grew hotter than the disc around it. A protoplanetary disc with a diameter of around 200 AU (30 billion km; 19 billion mi) with a hot, dense protostar in its centre was formed when the contracting nebula rotated more quickly. The planets were created by the accretion of material from this disc, wherein gravitationally attracted dust and gas coalesced to form ever-larger masses. There may have been hundreds of protoplanets in the early Solar System; however, they either combined, perished, or were expelled, leaving the planets, dwarf planets, and other small bodies.

 

Only metals and silicates could live in solid form in the warm inner Solar System close to the Sun due to their higher boiling temperatures, and these eventually gave rise to the rocky planets of Mercury, Venus, Earth, and Mars. The terrestrial planets could not grow very large because metallic elements made only a very minor portion of the solar nebula. The frost line, which is the region between Mars and Jupiter's orbits where material is cool enough for volatile icy compounds to remain solid, is where the giant planets (Jupiter, Saturn, Uranus, and Neptune) originated.These planets were able to become huge enough to hold a significant amount of hydrogen and helium, the lightest and most abundant elements, because the ices that formed them were more numerous than the metals and silicates that built the terrestrial inner planets. The asteroid belt, Kuiper belt, and Oort cloud all include leftover debris that never formed planets. The Nice model provides an explanation for the formation of these regions as well as how the outer planets might have arisen in various locations and moved through various gravitational interactions to take up their current positions.

 

The protostar's hydrogen centre saw a pressure and density increase within 50 million years that enabled thermonuclear fusion to start. When hydrostatic equilibrium was reached, the temperature, reaction rate, pressure, and density all increased as the thermal pressure balanced the pull of gravity. The Sun now belongs to the main-sequence of stars. The Sun's main-sequence phase will run from start to finish for around 10 billion years, as opposed to about 2 billion years for all preceding phases of the Sun's pre-remnant life taken together.The heliosphere was made by the solar wind, which also carried the protoplanetary disc's residual gas and dust into interstellar space. The Sun is becoming brighter as helium builds up at its core; early in its main-sequence existence, it was 70% brighter than it is now.

 

Solar System

Up until the Sun's core is completely changed from hydrogen to helium, which will happen in around 5 billion years, the Solar System will essentially remain as it is today. The Sun's main-sequence life will come to an end at this point.The Sun will become a red giant and its outer layers will enlarge to nearly 260 times its present diameter. The Sun's surface will be colder than it is on the main sequence (2,600 K (2,330 °C; 4,220 °F) at its coolest) due to its larger surface area.

 

Venus and Mercury are predicted to be vaporised by the growing Sun, making Earth uninhabitable (possibly destroying it as well).The Sun will burn helium for a fraction of the time it burnt hydrogen in the core when the core is eventually heated enough for helium fusion. Nuclear reactions at the Sun's core will slow down because it is too small to start fusing heavier elements. A dense white dwarf, only slightly larger than Earth but with half the original mass of the Sun, will remain when its outer layers are expelled into space. The expelled outer layers will create a planetary nebula, which will replenish the interstellar medium with some of the Sun's original material that has been enriched with heavier elements like carbon.