The Cosmic Perspective 3.1 - 3.4 Notes

Introduction to Science & Astronomy

• Science combines imagination, mathematics, and beauty; it progresses through careful observation and testing.

3.1 Ancient Roots of Science

• Scientific Thinking:

  • Developed through everyday experiences.

  • Examples: Children discover gravity by dropping objects, learning via trial and error.

  • Scientific thinking can be viewed as organizing common observations to share discoveries effectively.

• Ancient Astronomy:

  • Astronomy is considered one of the oldest sciences due to its extensive history and impact on timekeeping, navigation, and agriculture.

  • Historical Observations: Cultures used the Moon's cycle and stars for predicting weather patterns and determining time.

3.2 Timekeeping and Ancient Structures

• Ancient civilizations like Egyptians and Mayans created structures aligned with celestial events.

  • Examples include sundials, obelisks, and sites like Stonehenge, which align with solstices.

• Calendar Development:

  • Calendars originated from tracking lunar phases and seasons.

  • The Jewish calendar still reflects these principles with intercalation techniques to keep lunar and solar calendars synchronized.

3.3 Copernican Revolution

• Marked a shift from Earth-centered models (Ptolemaic) to Sun-centered models (Copernican).

• Copernicus proposed celestial bodies orbit the Sun, simplifying explanations of retrograde motion.

• Tycho discovered the supernova

• Supernova: A powerful explosion that marks the death of a star, significantly increasing its brightness for a short period.

• Tycho proposed that the Sun orbits the Earth while all other planets orbit the sun - was not taken seriously.

• Kepler's Contributions: - Established laws of planetary motion:

  • First Law: Orbits of planets are ellipses with the Sun at one focus.

    • Perihelion: Point where planet is closest to the sun

    • Aphelion: Point where planet is farthest from the sun

  • Second Law: Planets sweep out equal areas in equal times.

  • Third Law: The square of a planet's orbital period is proportional to the cube of its average distance from the Sun (p² = a³)

    • p = orbital period (years)

    • a = semimajor axis (astronomical units (au))

3.4 Nature of Science

• Key characteristics of science include:

  • Focus on natural explanations.

  • Development and testing of models.

  • Predictions that can be tested and modified.

• Distinction from Nonscience: Science relies solely on things that can be tested and are verifiable, while nonscience may rely on belief without testing.

• Common Misconceptions:

  • Theories in Science vs Everyday: A scientific theory is well-tested and widely accepted whereas, in everyday usage, it often refers to a guess.

Conclusion

• The evolution of astronomical thought showcases the transition from myth-based explanations of the universe to evidence-based science, revealing humanity's quest for understanding through observation, experimentation, and the development of robust scientific theories.