Pre-Finals Set A Flashcards
How is the universe everything?
- It includes all of space and all the matter and energy that space contains.
- It even includes time itself, and, of course, it includes you.
- Earth and the Moon are part of the universe, as are the other planets with many dozens of moons.
- Along with asteroids and comets, the planets orbit the Sun.
- All the stars in all the galaxies and all the other stuff that astronomers cannot even observe are all part of the universe.
Who perceived that the Earth was flat and had corners?
Early Babylonian, Chinese, Egyptian, and Hebrew civilizations during ancient times.
Who debunked that Earth is round and not flat?
Philosophers
the first astronomer to explain the retrograde motion of the planets in the sky.
Eudoxus of Cnidus
A Greek Mathematician who served as Aristotle’s teacher.
Eudoxus of Cnidus
designed his model of the universe as a series of cosmic spheres containing the stars, the sun, and the moon all built around the Earth at its center
Eudoxus of Cnidus
The first Geocentric model created.
By Eudoxus of Cnidus
The Sun, Moon, the planets, and the fixed stars move around in spheres that extend outward from the center.
Eudoxus of Cnidus
- The outermost sphere contains fixed stars.
- The only known planets at the time (Mercury, Venus, Mars, Jupiter, and Saturn) each have four spheres while the Sun and Moon have two.
Eudoxus of Cnidus
Greek philosopher and astronomer, considered the model proposed by Eudoxus, but he considered these spheres as physical entities.
Aristotle
defined the centric spheres as tangible entities filled with a “divine” and eternal substance called an “ether” that caused the spheres to move.
Aristotle
He also emphasized that Earth remained stationary in its place at the center, and it was spheres that spun eternally around it.
Aristotle
Introduced the concept of Prime Mover as the ultimate driver of all motion in the universe.
Aristotle
A Greek astronomer and mathematician, who made the first attempt to create a heliocentric model, which places the sun at the center of the universe.
Aristarchus of Samos
attempted to calculate the relative distance between the Earth and the Sun
Aristarchus of Samos
said that smaller celestial bodies must orbit the larger ones and since the Sun is much larger than the Earth, then the Earth must orbit around the Sun.
Aristarchus of Samos
In his model called the heliocentric model, the Moon, the Earth, and the then-known five planets revolved around the Sun in different sizes of orbits at different speeds.
Aristarchus of Samos
what year was Claudius Ptemaeus (Ptolemy) born?
born c. 90 A.D
a Greco-Egyptian astronomer and mathematician who proposed his own geocentric model of the universe.
Claudius Ptemaeus (Ptolemy)
He accounted for the apparent motions of the planets around the Earth by assuming that each planet moved around a sphere called an epicycle.
Claudius Ptemaeus (Ptolemy)
The center of the epicycle then moved on a larger sphere
deferent
introduced the concepts of epicycle, deferent, and equant to explain the observed “imperfect” motions of the planets.
Ptolemaic model (by Ptolemy)
A Polish astronomer who reintroduced the idea of a heliocentric universe.
Nicholaus Copernicus
He then reasoned that because Earth is spherical, then its motion is circular.
Nicholaus Copernicus
He also explained that the apparent retrograde motion observed by past and present scholars is an illusion that arises from the speed of the Earth’s orbital motion differing from that of the other planets and the similar direction (counterclockwise) of their orbits.
Nicholaus Copernicus
He is also a scholar-priest, originally known as Mikolaj Kopernik of Poland
Nicholaus Copernicus
Danish astronomer who also made planetary observations.
Tycho Brahe
He was skeptical of Copernicus’ model and sought to use his giant sextant to disprove the model.
Tycho Brahe
he published a model that serves as a compromise between Ptolemy’s geocentric and Copernicus’ heliocentric models.
Tycho Brahe
Earth was at the center and the sun, the moon revolved around it, and all the other planets orbited the sun.
Tychonic System (Tycho Brahe)
According to his model, the Sun’s massive size is what attracts the other planets to revolve around it.
Tycho Brahe
How did Tycho Brahe’s model get disproved?
he was unable to explain what force is associated with its massive size that makes the Sun able to attract the planets.
What are the weaknesses of the geocentric models?
- The observations of ancient Greeks showed that the paths of the celestial bodies are elliptical instead of circular, and as such, they vary in their distances away from the Sun. This is opposed to what they initially believed that the Sun, Moon, stars, and planets were moving in a uniform circular motion.
- Without the system of independently rotating nested spheres or epicycles and deferents, the geocentric models will be unable to account for retrograde motion.
What are the astronomical events known before the advent of telescopes?
- Diurnal Motion
- Precession
- Annual motion
- Eclipse
the apparent daily motion of the stars, including the Sun as seen from the Earth due to the Earth’s rotation.
Diurnal Motion
What is the sun’s diurnal motion?
counter-clockwise
(as the sun rises in the east, and sets in the west)
What are the stars’ diurnal motion?
counterclockwise around Polaris
the apparent yearly motion of the stars, including the Sun as seen from the Earth due to the Earth’s revolution around the Sun.
Annual Motion
The plane that defines the Earth’s equator that extends such as it also divides the celestial sphere in half
Equatorial plane
Edge of the equatorial plane
celestial equator
What happens to the sun’s declination as it undergoes annual motion?
it changes with the season
What is the sun’s declination?
it is at maximum during summer and minimum during winter.
The points of maxima and minima
Solstices
What are the two Solstice?
Summer and Winter Solstice
a solstice where the day is longer than night.
Summer Solstice
a solstice where nighttime is longer than daytime
Winter Solstice
The sun also intersects the celestial equator twice during a year at two points. What are these two points called?
Equinoxes
What happens in the equinoxes?
The length of daytime is the same as the length of nightime.
What happens in the equinoxes?
The length of daytime is the same as the length of nighttime.
What are the two equinox?
Vernal and Autumnal Equinox
also known as “Spring Equinox”; happens every March
Vernal Equinox
equinox that happens every September
Autumnal Equinox
the apparent motion of the equinoxes along the ecliptic as the Earth wobbles.
Precession
occur when either the Earth or moon cast a shadow into each other.
Eclipse
two kinds of eclipse
Solar and Lunar Eclipse
the Moon gets in the way of the Sun’s light and casts its shadow on Earth. That means during the day, the Moon moves over the Sun and it gets dark.
Solar Eclipse
Earth gets in the way of the Sun’s light hitting the Moon. That means that during the night, a full moon fades away as Earth’s shadow covers it up.
Lunar Eclipse
