Chapter 3 Notes

Chapter 3: The Science of Astronomy

3.1 The Ancient Roots of Science

In what ways do all humans use scientific thinking?

Scientific thinking is based on everyday observations and trial-and-error experiments.

How did astronomical observations benefit ancient societies?

Ancient people used observations of the sky to keep track of the time and seasons and as an aid in navigation.

What did ancient civilizations achieve in Astronomy?

-Determining the Time of the Day

-Making the Seasons

-Lunar Calendars(The Lunar calendar is still used in the Muslim Religion)

(Accurate calendars, eclipse prediction, navigational tools, and elaborate structures for astronomical observations.)

3.2 Ancient Greek Science

Why does Modern science trace its roots to the Greeks?

They developed a tradition of trying to understand nature without relying on supernatural explanations, and working communally to debate and challenge each others ideas.

-The Greeks used mathematics to give precision to their ideas.

-The Greeks saw the power of reasoning from observations.

Models

A conceptual representation created to explain and predict observed phenomena.

Geocentric

"Earth-centered"

How did the Greeks Explain planetary motion?

Ptolemaic Model

Each planet moves on a small circle whose center moves around Earth on a larger circle.

How did Islamic scientists preserve and extend Greek science?

-Scholars working in the Muslim empire translated and saved many ancient Greek works.

-They established a "House of Wisdom" much like the Library of Alexandria.

3.3 The Copernican Revolution

Copernican Revolution

Adopted a sun centered model and fundamentally changed the way we perceive our place in the Universe.

Tycho Brahe(1546 - 1601)

Tycho's accurate naked-eye observations provided the data needed to improve the Copernican System. 

Johannes Kepler(1571 - 1630)

Hired by Tycho. Discovered that planetary orbits are not circles but instead are a special type of oval called and ellipse.

Foci

(Singular) Focus

Eccentricity

A quantity that describes the amount by which an ellipse is stretched out compared to a perfect circle.

What are Kepler's Three laws of Planetary Motion?

Kepler's 1st Law: The orbit of each planet about the Sun is an ellipse with the Sun at one focus.

Perihelion

Closest point(Closest to the Sun)

Aphelion

Farthest point

Kepler's 2nd Law: As a planet moves around its orbit, it sweeps out equal areas in equal times.

Kepler's Third Law: More distant planets orbit the sun at slower average speeds, obeying the precise mathematical relationship: p2(squared) = a3(cubed)

p: The square of each planet's orbital period.

a: Average distance from the sun.

How did Galileo solidify the Copernican Revolution?

Galileo's experiments and telescopic observations overcame remaining scientific objections to the Copernican idea, sealing the case for the Sun-centered Solar System.

3.4 The Nature of Science

Occam's Razor

The idea that scientists should prefer the simpler of two models that agree equally well with observations.

-Individual scientists inevitably carry personal biases into their work, but the collective action of many scientists should ultimately make science objective.

Paradigm

Fall too far outside the general patterns of thought.

Theory

When a powerful yet simple model makes predictions that survive repeated and varied testing.