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1. Introduction to the Solar System

• The Solar System consists of the Sun, eight planets, numerous dwarf planets, moons, asteroids, comets, and other celestial bodies, all gravitationally bound to the Sun.

• It formed about 4.6 billion years ago from the gravitational collapse of a giant interstellar molecular cloud.

2. The Sun

• The Sun is a G-type main-sequence star (yellow dwarf) and the central object of our Solar System, accounting for roughly 99.8\% of its total mass.

• It is primarily composed of hydrogen (74\%) and helium (24\%), with trace amounts of other elements.

• The Sun produces energy through nuclear fusion, converting hydrogen into helium in its core.

3. Planets

The Solar System has eight planets, broadly categorized into inner (terrestrial) and outer (gas/ice giant) planets.

3.1 Inner (Terrestrial) Planets

• Characterized by rocky compositions, solid surfaces, and relatively higher densities.

• Mercury:

  • Smallest planet, closest to the Sun.

  • Extreme temperature variations between day and night due to lack of atmosphere.

• Venus:

  • Similar in size to Earth.

  • Known for its dense, toxic atmosphere (primarily carbon dioxide) and runaway greenhouse effect, making it the hottest planet.

• Earth:

  • The only known planet to harbor life.

  • Unique for its liquid water on the surface and a nitrogen-oxygen atmosphere.

• Mars:

  • Often called the "Red Planet" due to iron oxide on its surface.

  • Has a thin atmosphere, polar ice caps, and evidence of past liquid water.

3.2 Outer (Gas and Ice Giant) Planets

• Much larger than terrestrial planets, composed mainly of hydrogen, helium, methane, and ammonia.

• Jupiter:

  • Largest planet in the Solar System.

  • A gas giant known for its Great Red Spot, a persistent storm larger than Earth.

  • Has a strong magnetic field and many moons (e.g., Ganymede, Europa).

• Saturn:

  • Famous for its prominent system of rings, composed mostly of ice particles and rock fragments.

  • A gas giant, second largest in the Solar System.

• Uranus:

  • An ice giant, notable for its axial tilt of nearly 90 degrees, causing it to orbit on its side.

  • Bluish-green color due to methane in its atmosphere.

• Neptune:

  • An ice giant, similar in composition to Uranus.

  • Known for its strong winds, dynamic storms, and deep blue color.

4. Dwarf Planets

• Celestial bodies orbiting the Sun that are massive enough to be nearly spherical but have not cleared their orbital path of other debris.

• Examples include Pluto, Eris, Ceres (also an asteroid), Makemake, and Haumea.

5. Other Components

• Asteroids:

  • Rocky, airless remnants left over from the early formation of our solar system.

  • Most are found in the asteroid belt between Mars and Jupiter.

• Comets:

  • Icy, small solar system bodies that, when passing close to the Sun, warm up and release gases, a process called outgassing, displaying a visible coma (atmosphere) and often a tail.

  • Originate from the Kuiper Belt and Oort Cloud.

• Moons (Natural Satellites):

  • Celestial bodies that orbit planets or dwarf planets.

  • Earth has one moon; other planets have many (e.g., Jupiter, Saturn) or none (e.g., Mercury, Venus).

• Kuiper Belt:

  • A region of the solar system beyond the orbit of Neptune, thought to contain many comets, asteroids, and other small bodies made largely of ice.

• Oort Cloud:

  • A theoretical spherical cloud of icy planetesimals believed to surround the Sun at distances ranging from 2,000 to 200,000 AU (0.03 to 3.2 light-years), acting as the source for most long-period comets.