Earth Science: The Universe and Solar System

Universe Overview

• The universe encompasses all matter, energy, planets, stars, galaxies, and space.
• Cosmology is the scientific study of the universe's origin.

Age of the Universe

• The universe is estimated to be approximately 13.8 billion years old.
• Age determination methods include estimating the oldest star and measuring the universe's expansion rate.

Composition of the Universe

• Composed of 5% normal matter, 25% dark matter, and 70% dark energy.
• Normal matter forms stars and planets; dark matter doesn't emit light and dark energy drives expansion.
• In a closed universe scenario, sufficient matter density could halt expansion, leading to a contraction and eventual collapse.

Solar System Overview

• The solar system includes all celestial bodies orbiting the Sun, located in the Milky Way Galaxy, and is about 4.6 billion years old.

Geocentric and Heliocentric Models

• Geocentric Model: Proposed by Ptolemy, suggesting Earth is the center of the solar system, with the Sun and planets orbiting it.
• Heliocentric Model: Introduced by Copernicus, positing that the Sun is the center, and planets, including Earth, orbit around it.

Theories on the Origin of the Solar System

• Buffon’s Collision Theory: Claims planets formed from debris generated by a collision between the Sun and a giant comet.
• Solar Nebular Theory: Suggests formation from a hydrogen gas and dust cloud that collapsed, potentially triggered by a supernova explosion, resulting in the Sun and planets.

Earth and Its Uniqueness

• Earth is the only known planet in our solar system with conditions suitable for supporting life, emphasizing its uniqueness in the universe.