Exam 2

Question 0

Nicolas Copernicus 1473-1543

Answer 0

Through the use of geometry, he was able to determine the relative distances of the planets from the sun. He assumed that planetary orbits are circular, which is problematic only in the cases of mercury and Mars.

Question 1

Why most bright stars are known by Arabic names?

Answer 1

During the dark ages astronomy and astrology flourished in Arabic countries but not in Western Europe

Question 2

Cinquefoil

Answer 2

5 pearled rose found in Christian symbolism “Rose of Venus” the rose with its characteristic 5 pedals shade mimicked the pentagram spate traced by the planet Venus in the night sky.

Question 3

The Ptolemaic system

Answer 3

Was a geocentric model for the universe either he sun moon, and planters revolving around the earth. Each planet moves in a double circle, accounting for the observed retrograde motions.

Question 4

Retrograde Motion

Answer 4

Natural consequence of the fact that the earth is also in motion about the sun

Question 5

Claudius Ptolemy (his model of the universe)

Answer 5

By the Renaissance, the Ptolemaic model of the universe has been generally accepted since its publication in the Almagest (140 CE)

Question 6

Heliocentric

Answer 6

Universe that revolves around the SUN

Bc no annual parallax was observed for the stars, the notion of heliocentric universe was abandoned

Question 7

Geocentric

Answer 7

Universe that revolves around the earth

Question 8

Aristarchus concluded..

Answer 8

That the sun was about 19 times larger than the moon and therefore about 5 times larger than the earth.
In fact, it is 109 times larger! The important point was that the sun was in fact bigger than the earth. This naturally lead to the suggestion that the earth might revolve around the sun rather than vice versa.

He also determine the moon is 1/4 the size of the earth. He did this by comparing the apparent sizes of the moon and the umbra of the earth shadow, and using a bit of geometry.

Question 9

Aristarchus of Samos 320-250 BCE

Answer 9

Attempted to determine the relative distances of the sun and moon by measuring the angle between them at the instant of first quarter moon..

he was way off!

Question 10

Eratosthenes (276-195)

Answer 10

A librarian at Alexandria, first accurately determined the size of the earth!

Question 11

3 pieces evidence that gave astronomers the idea that the earth was round (Aristotle!!)

Answer 11

1. As one travels northward along the earths surface, the North Star appears progressively higher in the sky.
2. As a ship sails away from port (and appears to diminish in size) the ship vanishes from sight first, then the hill and finally the tops of the mountains.
3. The most compelling reason.. Lunar eclipses!

Question 12

Two important geometric fact that Pythagoras gave us:

Answer 12

1. The sum of the angles in a triangle always add up to 180 degrees
2. When two parallel lines are but by a third line the alternate interior angles must be equal.

Question 13

Hipparchus

Answer 13

Devises the stellar magnitude system which we still use today.

Also, the 26,000 year PRECESSION of the earths rotation axis. Like a top or gyroscope, the Earth’s rotation axis moves in a conical fashion with a period of about 26,000 years.

He used a solar eclipse which occurred in March of 190 BC to measure the difference in direction to the moon as viewed from two locations on Earth. This allowed him to crudely estimate the Moons distance.

Question 14

Herakilides of Pontus 388-315 BC

Answer 14

Contradicting the accepted model of the universe put forward by Aristotle, he proposed that the earth rotates upon its axis. He also thought that the observed motions of Mercury and Venus suggested that they orbited the sun rather than the Earth.

Question 15

Stonehenge

Answer 15

Prehistoric Monument: Used as a calendar and may have been used to predict eclipses.

Question 16

The First law of Science

Answer 16

“For every observable effect, there is a physical cause”

Question 17

The lack of observed parallax for celestial bodies led ancient people to believe…

Answer 17

.. That the earth was flat and surrounded by crystalline sphere which rotated eastward once a day.

(Image of land sitting on the turtle with the celestial sphere around it)

Question 18

Pythagoras of Samos (570-495 BCE)

Answer 18

Was a Greek philosopher and mathematician; he founded a mystic religious movement called Pythagoreanism.

a^2 + b^2 = c^2

Question 19

What always casts a circular shadow on the the moon during a lunar eclipse?

Answer 19

The Earth

Question 20

Eudoxes of Cnidus (410-335 or 347 BCE)

Answer 20

Greek astronomer, mathematician and student of Plato. All of his original work is lost to antiquity.

Proposed that the sun, moon and five naked-eye planets and one (the outermost) carrying the stars.

Question 21

Anaxagoras (500-428 BCE)

Answer 21

Was according to historians, the first person to determine the true causes of eclipses and lunar phases.

Concluded that the sun is a luminous body and the earth and moo are not.

Question 22

Aristotle (384-322 BCE)

Answer 22

Perhaps the most influential philosopher of all time, he realized that lunar eclipses provide direct evidence that the earths spherical in shape.

Question 23

Kepler’s 1st Law

of planetary motion

Answer 23

Each planet orbits the Sun in a path which an ellipse, with the Sun at one focus.

An ellipse is an example of a conic section.
The shape of an ellipse is described by its eccentricity.

Question 24

Eccentricity

Answer 24

How am ellipses shape described. | 0(

Question 25

Johannes Kepler 1571-1630

Answer 25

Was a theoretician. Wrote Kepler's Three Laws or Planetary Motion are empirical laws, based upon Brahe's observations, which describe how the planets revolve about the sun.

Question 26

Ellipse

Answer 26

Example of a comic section (circle parabola, and hyperbola). The defining properties of an Ellipse is the sum of the distances between a point on the ellipse and the two focal points is the same for all points on the Ellipse. The size of an ellipse is described by its semi major axis which is equal to half the major axis. The shape by the eccentricity. The closer to 1 the ellipse the more elongated the ellipse is. The distance between the center of an ellipse and either focus is equal to the quantify ae.

Question 27

Kepler's 2nd Law (of planetary motion)

Answer 27

An imaginary line joining a planet to the sun sweeps out equal areas in space in equal time intervals. This allows us to predict a planets position at any time in the future! "Kepler's law of Areas" (Aphelion and perihelion)

Question 28

Perihelion

Answer 28

The point in its orbit closest to the sun. Where the planet travels fastest!

Question 29

Aphelion

Answer 29

The point farthest from the sun. The slowest point of orbit.

Question 30

As a planet orbits the sun.. the product of its ORBITAL SPEED and its DISTANCE from the sun remains..

Answer 30

(Very nearly) constant

Question 31

Kepler's Third Law (of planetary motion) Published in 1619

Answer 31

The square of a planets orbital period is proportional to the cube of its semimajor axis. Reworded: planets orbital period (p) squares is proportional to the cube of the average distance (a) btwn that planet and the sun. Math terms: a^3 (is proportional) p^2 Where a and p represent the semimajor axis and period. To convert this Propontis life j to an equation required intro of a conversion fact a^3= kP^2 l; what value k has is determined by what units a and P are measured in. If AU and years are used then k=1. In the case a^3=P^2 only if measures in AU and years!! (Harmonic law) Kepler believed he had stumbled upon the underlying harmony of the universe.. Mercury, traveling fastest in its orbit has the highest pitch and then Saturn be lowest.

Question 32

Newtons 1st Law (of motion)

Answer 32

LAW OF INERTIA | Any body maintains a constant velocity unless some net force act upon that body

Question 33

In a level flight, the thrust of the engine _______ the drag of ____ ________, and the lift exactly balances the weight of the airplane. The net force is ____! The aircraft flies in a horizontal path at ________ speed.

Answer 33

Balances Air resistance Zero Constant

Question 34

Newtons 2nd Law | (of motion)

Answer 34

THE FORCE LAW If a net force acts upon a body, the body responds by accelerating in the direction of the net force, and inversely proportional to the body's mass. F=ma or a=F/m Note: that this is a veto equation so the directions of F and a are identical!

Question 35

The metric of force

Answer 35

Newton 1 Newton= 1 kilogram x 1 meter/second^2 (1 Newton= 0.225 pounds) (1 pound= 4.44 Newtons)

Question 36

Newtons 3rd Law (of motion)

Answer 36

THE REACTION LAW If one body exerts a force upon a second body, the second object exerts an equal (in strength) and opposite (in direction) force upon the first Also referred to as the ROCKET PRINCIPLE: Since rockets reply on the idea of action and reaction. The force with which the exhaust gas is expelled from a rocket equals the force driving the rocket upwards. When a gun is fired the gun and the bullet experience equal (and opposite) forces. The bullet does almost all the moving bc it has a smaller mass.

Question 37

Terminal velocity

Answer 37

Upward force of air resistance would equal the downward force of gravity, the Net Force would be zero.

Question 38

Gravity vs. normal force

Answer 38

Gravity: pulls downward; this represents the weight of an object. Normal force: is the force that the floor exerts upward which exactly balances the force of gravity; the net force in the vertical direction is Zero.

Question 39

Force

Answer 39

Represents a "push" or a "pull"

Question 40

Vectors vs. Scalars

Answer 40

Vectors: quantities which have direction (velocity is vector) Scalar: quantities that don't (such as temperature that don't) speed is scalar.

Question 41

Velocity

Answer 41

Described both the SPEED and the DIRECTION of an objects motion.

Question 42

Acceleration

Answer 42

Rate at which a body's velocity changes; it is a vector. Any change in speed or direction or motion represents an acceleration. Force( F )/ Mass ( M )

Question 43

Weight | What does g represent?

Answer 43

The force of gravity acting upon it W=mg g being 9.8m/s or 32 ft/s m being the objects mass Your weight depends not only upon your mass, but also upon the mass and radius of the planet where you live!

Question 44

Air resistance

Answer 44

Will cause the body to fall more slowly

Question 45

Newtons law of Universal Gravitation

Answer 45

"Between any two bodies there exists a force of mutual attraction. The strength of this force is proportional to the product of the masses of the two bodies, and Inversely proportional to the square of the distance between their centers" F=G x m1 x m2/ r2 G: constant- 6.67x10^-11 N x m^2 x kg^-2 Note that the forces are equal. However, since a=f/m the less massive body experiences greater acceleration.

Question 46

Galileo's law of falling bodies

Answer 46

In the absence of air resistance all falling bodies near earth's surface fall with equal acceleration g=9.8 m/sec^2= 32 ft/sec^2 If define your weight (W) as being the force of gravity acting on you, then W=mg, where m is your mass

Question 47

Astronomical unit

Answer 47

Is the average distance between btwn Earth and Sun 1AU= 92,960,000 miles = 149,600,000 kilometers = 8.32 light minutes

Question 48

Ptolemaic system vs. Copernicus system

Answer 48

Pt.: geocentric all the planets are revolving around the epicycle while also revolving around the earth (retrograde motion) Cop: heliocentric planets revolving around the deferent. The moon while also revolving around the epicycle around the earth

Question 49

Calculating a planets distance from Earth to AU..

Answer 49

If we can measure that planets distance in miles or kilometers then the length of the AU is determined. This is accomplished though the parallax method, though it's much harder than doing this for the moon b\c even even when close st. Venus are hundred of times father away

Question 50

During the 18th and 19th centuries the rare transits of Venus (1761,1769,1874,1882)..

Answer 50

Provided the best opportunities for precise determinations of the astronomical unit, yielding values accurate to within 0.2%

Question 51

Radar raining

Answer 51

A radar pulse is beamed at a solar system object , and the round trip time is measured. Multiplying by the speed of light

Question 52

Synodic Periods

Answer 52

Time between one opposition of planet and the next (or time btwn one inferior conjunction and plants) S represents the planets synodic period. P is orbital period, and E the orbital period of the earth (one year or 365.24; the units must be concerts 1/S= | 1/7.3-1/orbital- period period|

Question 53

1577 supernova

Answer 53

New star that I appeared I in the constellation classic piera. Aristotle has taught that the heavens are perfect, unchanging and eternal. Any unforeseen event I the sky (such as a comer or meter) was believed to be some sort do an atmospheric

Question 54

Tycho Brahe 1546-1601

Answer 54

The uraniborg (city of stars) Denmark Had a telescope; his instruments were large permanently mounted position- measuring devices He devoted his life to precisely measuring the positions of the moon, planets and stars near the end of this life he hired the mathematician Johannes Kepler to try and "make sense" of His data

Question 55

The religious climate was much more temperate in Northern Europe. In Denmark, we find the first example of a division labor in the persons of _______ ________ (the greatest observational astronomer pre-telescope) and his assistant _______ _______ (a theoretical astronomer)

Answer 55

Tycho Brahe | Johannes Kepler

Question 56

By the time if Copernicus death, in much of Europe, to believe in a __________ universe was considered heresy bf the Catholic Church. In 1600s _______ ________ was executed by the inquisition for a variety of crimes against the church, including teaching the _______ system.

Answer 56

Heliocentric Gordano Bruno Copernican

Question 57

What laid the foundation for modern astrophysics

Answer 57

Tycho Brahe had accurately measured the moons parallax, and therefore it's distance. However, he couldn't measure a parallax for the new star. That meant that it must lie beyond the moon in celestial space, refuting the Aristotelian contention bag the heavens are perfect and unchanging. In fact, they might be governed by the same natural laws which operate here in earth!

Question 58

Galileo Galilei 1564-1642 | Discoveries!

Answer 58

1. THE MOON IS NOT SMOOTH, covered with mountains and craters. The tallest mountain exceeds Everest over three times. The moon posses neither atmospheric not liquid water 2. The sun rotates about an axis over period of roughly four weeks, and possesses surface blemishes known as SUN SPOTS 3. The PLANETS SHOWING CIRCULAR DISKS disks when viewed through the telescope, differ fundamentally from stars. 4. The MILKY WAY a grayish band of light that circles the sky, consists of innumerable faint stars. This suggested that there were many more stars than 6000 visible to the unaided eye. 5. JUPITER POSSES 4 MOONS (the Galilean satellites) which orbit the planet with periods of two to seventeen days. This demonstrated that all celestial bodies do not resolve around the earth! 6. The planet VENUS EXHIBITS ALL THE PHASES WHICH OUR MOON DOES this indicates that the Ptolemaic model (in which Venus is always between the Earth and Sun, and should only appear In new or crescent phase) was fundamentally flawed.

Question 59

Inferior planets

Answer 59

(Mercury and Venus) are located closer to sun than the earth

Question 60

Superior planets

Answer 60

(Mars, Jupiter, and Saturn) are farther away

Question 61

Elongation

Answer 61

Is the angle (along the ecliptic) between the directions to the Sun and the planet.

Question 62

Conjunction Opposition Quadrature

Answer 62

Conjunction(full) Superior conjunction(full)