The Earth and the Solar System

Solar system

  1. The Solar System consists of the Sun, eight planets, moons, dwarf planets, asteroids, comets, and other celestial objects.
  2. The Sun is the center of the Solar System and accounts for 99.86% of its total mass.
  3. The eight planets are classified as terrestrial planets (Mercury, Venus, Earth, Mars) and gas giants (Jupiter, Saturn) and ice giants (Uranus, Neptune).
  4. Mercury is the closest planet to the Sun and has no atmosphere to retain heat.
  5. Venus

Earth's motions

  1. The Earth has two primary motions: rotation and revolution.
  2. Rotation refers to the Earth spinning on its axis.
  3. The Earth completes one rotation in approximately 24 hours, causing day and night.
  4. The axis of rotation is tilted at an angle of 23.5° relative to the plane of its orbit.
  5. Revolution refers to the Earth's orbit around the Sun.
  6. One complete revolution takes approximately 365.25 days, leading to the concept of a year.

Structure of the Earth

  1. The Earth is divided into three main layers: the core, mantle, and crust.
  2. The crust is the Earth's outermost layer, comprising solid rocks and minerals.
  3. The thickness of the crust varies from 5 km under oceans to 70 km under continents.
  4. The crust is divided into the continental crust and oceanic crust.
  5. The continental crust is primarily composed of granite, while the oceanic crust is made of basa

Origin of the Earth

  1. The Earth is a part of the Solar System, which includes the Sun, eight planets, and other celestial bodies.
  2. The Big Bang Theory explains the origin of the universe approximately 13.8 billion years ago.
  3. The Solar System is believed to have formed about 4.6 billion years ago.
  4. The nebular hypothesis proposed by Immanuel Kant and Pierre-Simon Laplace suggests the Solar System formed from a rotating cloud of gas and dust.
  5. The protostar at the center of the nebula eventually b
The Earth and the Solar System