Big Bang and Formation of Solar System

The Big Bang and Solar System Formation

• The Big Bang Explosion occurred 13.6 billion years ago, marking the beginning of the universe.
• The Nebular Theory (1755) by Immanuel Kant and later modified by Laplace (1796) explains the formation of our solar system from a giant cloud of dust and gas called a nebula.
• The nebula underwent nuclear fusion, resulting in the formation of the Sun, mostly composed of hydrogen and helium.

Celestial Bodies

• There are two types of celestial bodies: luminous (self-glowing) and non-luminous (not self-glowing, but can reflect light from other sources).
• Examples of luminous bodies include stars, while non-luminous bodies include the Moon.
• Other types of celestial bodies include asteroids, meteoroids/meteors, comets, and stars.

Stars

• Stars are luminous bodies that vary in color depending on their temperature.
• A group of stars is called a constellation, with the largest constellation being Hydra.
• The brightest star in the Orion constellation is Rigel, while the brightest star in the night sky is Sirius (Dog Star).
• The closest star to Earth is the Sun, with a distance of 150 million km (1.5 x 10^8 km).

Solar System

• The Sun is the only star in our solar system and is the powerhouse of the solar system.
• It is composed of 73% hydrogen, 25% helium, and other metals.
• The Sun carries 99% of the mass of our solar system and takes 8 minutes and 30 seconds for light to reach Earth.

Moon

• The Moon is Earth's natural satellite and is non-luminous.
• It takes 1.26 seconds for the Moon's light to reach Earth, and it is 384,000 km away from Earth.
• The Moon has a gravity similar to Earth's and rotates/revolves in 27.3 days, with only one side visible from Earth.

Planets

• There are two types of planets: terrestrial (interior) and Jovian (exterior) planets.
• The asteroid belt is located between Mars and Jupiter.
• Terrestrial planets include Mercury, Venus, Earth, and Mars, while Jovian planets include Jupiter, Saturn, Uranus, and Neptune.

Terrestrial Planets

• Mercury is the closest planet to the Sun, with a diameter of 4900 km and no satellite.
• Venus is the hottest planet, with a thick atmosphere that traps gases easily.
• Earth is the only planet that supports life and has a satellite called the Moon.
• Mars is known as the "Red Planet" due to its rich iron oxide content.

Jovian Planets

• Jupiter is the largest planet, with a short rotation period of 10 hours and a massive atmosphere filled with hydrogen, helium, and other gases.
• Saturn is the second-largest planet, with bright and concentric rings made of tiny rocks, gas, dust, and ice.
• Uranus is an "Ice Giant" with a tilted axis, making it a "Rolling/Lopsided Planet".
• Neptune is the farthest planet, also an "Ice Giant" with a bluish color due to methane.

Dwarf Planet

• Pluto is no longer considered a planet, but a dwarf planet, and is a member of the Kuiper Belt.
• The Kuiper Belt is a spherical boundary outside the orbit of Neptune, containing asteroids, rocks, and comets.