[ASTR 111] Chapter 3 - Science of Astronomy

Scientific model

Conceptual representation created to explain and predict observed phenomena

Geocentric model

Placed spherical Earth at universe’s center; made by Greeks

Ptolemaic model

Explains apparent retrograde motion of planets

Copernican revolution

Story of origin of modern science

Foci

Rounded ends of an ellipse, singular, “focus”

Eccentricity

Quantity describing how much an ellipse is stretched out compared to a perfect circle

Kepler’s 1st law of planetary motion

Each planet’s orbit around the Sun is an ellipse, with the Sun at one focus; varying a planet’s distance from the Sun during orbit

Kepler’s 2nd law of planetary motion

Planet moves faster when orbiting near the Sun, and slower when further away, sweeping out equal areas in equal times

Kepler’s 3rd law of planetary motion

Distant planets orbit the Sun at slower average speeds

Pseudoscience

Claims to be science, but doesn’t follow the scientific method

Paradigm

General pattern of thought tending to shape scientific study during a particular time period

Theory

When powerful and simple models survive repeated and varied testing