Birth of Astronomy and Astrology Review

Flashcards testing core concepts, historical models, calculations, and vocabulary from Chapter 2: Birth of Astronomy and Astrology.

What six criteria define scientific thinking according to the CONPTT framework?

Consistent (reproducible results), Observable (detectable by senses or tools), Natural (explained by natural mechanisms), Predictive (makes testable predictions), Testable (subject to experimentation), and Tentative (subject to change with new evidence).

What is the zenith and horizon in an observer's local sky?

The zenith is the point directly above an observer's head, and the horizon is the boundary line where the sky appears to meet the ground.

How are the north celestial pole, south celestial pole, and celestial equator established?

The north and south celestial poles are the points in space where Earth's rotation axis extends to intersect the celestial sphere, and the celestial equator is the projection of Earth's equator onto the celestial sphere.

How does an observer's latitude affect their view of the celestial poles and star paths?

The altitude of the celestial pole above the northern horizon is equal to the observer's latitude. At the North Pole ($90^\circ\text{ N}$), the celestial pole is directly overhead; at the equator ($0^\circ$), the celestial poles lie on the horizon.

What is the circumpolar zone?

The region of the sky near the celestial poles containing stars that never rise or set below the horizon as Earth rotates.

What is the ecliptic, and why is it tilted relative to the celestial equator?

The ecliptic is the Sun's annual apparent path across the celestial sphere. It is tilted at an angle of $23.5^\circ$ to the celestial equator because Earth's rotation axis is tilted by $23.5^\circ$ relative to its orbital plane.

What is the apparent angular width of the Moon in the sky?

The Moon appears approximately $0.5^\circ$ wide in the sky, which corresponds roughly to the width of a pinkie finger held at arm's length.

How much does the Sun appear to move relative to background stars each day, and what impact does this have on rising times?

The Sun moves about $1^\circ$ eastward per day relative to the background stars, causing stars to rise approximately $4\,\text{minutes}$ earlier each day (or the Sun to rise $4\,\text{minutes}$ later relative to the stars).

What is the difference between an asterism and an official constellation?

An official constellation is one of 88 designated regions dividing the entire sky (e.g., Ursa Major), whereas an asterism is an informal, easily recognizable pattern of bright stars (e.g., the Big Dipper inside Ursa Major).

How did ancient civilizations like the Egyptians, Chinese, Mayans, and Polynesians apply early astronomy?

Egyptians created a $365\text{-day}$ calendar using Sirius to predict Nile flooding; Chinese recorded sunspots, comets, and meteors; Mayans tracked Venus for calendars; and Polynesians used star tracks for oceanic navigation.

How did Aristotle prove that Earth is spherical using lunar eclipses?

Aristotle observed that Earth's shadow cast upon the Moon during a lunar eclipse is always round, which can only be consistently produced by a spherical body.

How did Eratosthenes calculate the circumference of Earth around 200 BCE?

He measured that at noon on the summer solstice, sunlight fell straight down a well in Syene ($0^\circ$ shadow angle), while a column in Alexandria cast a shadow at $7^\circ$ ($1/50$ of a $360^\circ$ circle). Multiplying the $5{,}000\text{ stadia}$ distance between cities by 50 gave a circumference of $250{,}000\text{ stadia}$.

What is parallax?

Parallax is the apparent shift in the observed position of an object caused by a change in the observer's position.

What were the major scientific contributions of Hipparchus?

Hipparchus created a star catalog of about 850 stars, invented the system of apparent magnitudes, established celestial coordinates, and discovered the precession of Earth's axis.

What is precession, and how does it change the identity of the North Star over time?

Precession is the slow conical wobble of Earth's rotation axis over a cycle of about $26{,}000\text{ years}$. As a result, Thuban was the pole star ~5,000 years ago, Polaris is current, and Vega will be the pole star in ~14,000 years.

How did Ptolemy explain retrograde planetary motion in his geocentric model?

Ptolemy modeled planets moving on small circular paths called epicycles, whose centers revolved along larger circular paths called deferents centered near Earth, adding an equant point to refine speed predictions.

What is planetary retrograde motion in reality?

An apparent backward (westward) motion of a planet against background stars caused when Earth overtakes a slower-moving outer planet in its orbit.

What is natal astrology?

The belief system originating in ancient Babylonia and expanding in Greece that claims the positions of the Sun, Moon, and planets at the exact moment of birth dictate an individual's personality, future, and fortune.

Why are modern astrological sign dates misaligned with actual celestial constellations?

Due to the $26{,}000\text{-year}$ precession of Earth's axis since the zodiac system was codified over 2,000 years ago, astrological signs have shifted roughly one full constellation relative to the physical position of the Sun.

What did experiments by Michel Gauquelin and Geoffrey Dean reveal about why horoscopes seem accurate?

They showed that people readily accept vague, generalized descriptions as uniquely personal (the Forer/Barnum effect), even when given a mass murderer's horoscope (Gauquelin, 94% agreement) or completely inverted descriptions (Dean, 95% agreement).