Biology and Geology: The Earth in the Universe (1st ESO)

Summary

This textbook section introduces students to the fundamental concepts of astronomy, focusing on the Earth's place in the universe and the evolution of astronomical theories. It begins by exploring human fascination with the universe, from ancient times when stars and constellations were used for navigation and seasonal prediction, to the development of the Ptolemaic (Geocentric) Model, which placed the Earth at the universe's center.

Early Theories and Observations

• Ancient Observations: Early humans relied on the stars for guidance and to predict seasons, leading to the creation of myths and speculative theories about the universe's structure.
• Ptolemaic Model: For over 1500 years, this geocentric model, which posited the Earth at the universe's center, was widely accepted despite its inaccuracies.

The Shift to the Heliocentric Model

• Heliocentric Model: Observational inaccuracies in the geocentric model led to the development of the heliocentric theory, placing the Sun, not the Earth, at the center of the universe. This model was a significant shift in understanding celestial movements.

Modern Understanding of the Universe

• The Big Bang Theory: The most accepted theory for the universe's origin, suggesting that the universe began from a singularity approximately 13.8 billion years ago and has been expanding ever since.
• The Milky Way: Our planet resides in the Milky Way galaxy, orbiting a star we know as the Sun, which is not at the center of the universe.

Measuring the Universe

• Observable Universe: The vastness of the universe is highlighted, with the observable portion being so large that light takes 91 billion years to traverse it ​【oaicite:0】​