Moon Motions and Phases, Celestial Cycles, and Historical Astronomy

These flashcards cover key concepts related to the motions of celestial bodies, astronomical theories, and historical developments in astronomy, helpful for reviewing the lecture content.

Synchronous Rotation

The Moon always shows the same face to Earth because it rotates on its axis in the same time it takes to orbit Earth.

Ecliptic

The apparent path of the Sun through the background stars over the course of a year.

Retrograde Motion

The apparent motion of planets which first moves west to east, then reverses direction before resuming its original path.

Maximum Elongation

The maximum angular distance planets like Mercury and Venus can reach from the Sun in the sky.

Platonic Rules for Celestial Motion

The principles established by Plato, which stated that celestial motion is uniform, circular, and centered around the Earth.

Eudoxian Spheres

Models developed by Eudoxos to explain planetary motion using a system of concentric spheres.

Heliocentric Theory

The model proposed by Copernicus where the Sun is at the center of the universe with the planets including Earth orbiting around it.

Kepler's Three Laws of Planetary Motion

1. Planets move in elliptical orbits with the Sun at one focus. 2. A line joining a planet and the Sun sweeps out equal areas in equal times. 3. The square of the period of a planet's orbit is proportional to the cube of the semi-major axis of its orbit.

Occam's Razor

The principle that simpler explanations are more likely to be correct than complex ones.

Newton's Universal Law of Gravitation

A formula that describes the gravitational attraction between two objects based on their masses and distance apart.

Blackbody Radiation

The theoretical spectrum produced by an ideal object that absorbs all incident light and re-emits energy as electromagnetic radiation.

Doppler Effect

The change in frequency or wavelength of light from an object due to the motion of the object towards or away from the observer.

Spectroscopy

The study and analysis of the spectrum of light to determine the composition and properties of celestial objects.

Wien's Displacement Law

The law that states, as an object's temperature increases, the peak wavelength of its emitted radiation shifts to shorter wavelengths.

F= Gm₁m₂/r²

The formula defining the gravitational force between two masses, where G is the gravitational constant, m₁ and m₂ are the masses, and r is the distance between their centers.

Elliptical Orbits

Paths followed by planets around the Sun, which are not perfect circles but elongated shapes.