midterm exam

Question 1

metrics

Answer 1

tera, giga, mega, kilo, –, centi, milli, micro, nano

Question 1

visible light spectrum

Answer 1

400 to 700 nm

Question 2

cosmic rays

Answer 2

high energy protons

Question 3

scientific method

Answer 3

observation -> theory (hypothesis model) -> prediction -> experiment to test theory -> confirm or deny prediction -> revise theory -> observation …

Question 4

statistical uncertainty

Answer 4

adding more data will reduce the errors

Question 5

systematic uncertainty

Answer 5

uncontrolled aspect of the experiment, or incorrect assumption

Question 6

astronomical objects by size

Answer 6

galaxy cluster -> galaxy -> solar system -> star -> planet

Question 7

the celestial sphere

Answer 7

the inverted dome that stars and planets appear plastered on since they are so far away

Question 8

zenith

Answer 8

point on the celestial sphere directly overhead

Question 9

nadir

Answer 9

point on the celestial sphere directly underneath (not visible)

Question 10

celestial equator

Answer 10

projection of Earth’s equator onto the celestial sphere

Question 11

North celestial pole

Answer 11

projection of Earth’s north pole onto the celestial sphere. latitude 90º

Question 12

solar day

Answer 12

24 hours from noon to noon

Question 13

ecliptic

Answer 13

the projection of Earth’s orbit onto the celestial sphere

Question 14

sidereal day

Answer 14

it takes 23 hours and 56 minutes for star to star to come back to the meridian

Question 15

ecliptic crosses equator at

Answer 15

vernal equinox
autumnal equinox

Question 16

sun’s highest and lowest points relative to equator

Answer 16

summer solstice
winter solstice

Question 17

0 days moon

Answer 17

new moon

Question 18

7 days moon

Answer 18

first quarter

Question 19

14 days moon

Answer 19

full moon

Question 20

21 days moon

Answer 20

third quarter

Question 21

moon phases order

Answer 21

new moon -> waxing crescent -> first quarter -> waxing gibbous -> full moon -> waning gibbous -> third quarter -> waning crescent

Question 22

line of nodes

Answer 22

where two orbital planes cross

Question 23

eclipses happen when

Answer 23

can only happen when full or new moon occurs near the Line of Nodes

Question 24

lunar eclipse conditions

Answer 24

can only occur if the moon passes a node near full moon

Question 25

obliquity

Answer 25

cause of the seasons. axis of rotation is inclined.

Question 26

Precession

Answer 26

the slow gradual change in the orientation of a celestial body's rotational axis. used to describe the Earth's axis which slowly wobbles over time due to the gravitational pull of the sun and moon, causing the shifting of the celestial poles over thousands of years

Question 27

aristotle

Answer 27

earth is the center of the universe and does not move. planets move in perfect circles. planets move at a constant speed. celestial regions are perfect and unchanging.

Question 28

Aristarchus

Answer 28

discovered parallax

Question 29

parallax

Answer 29

seeing a star or planet from two locations should produce a shift in its apparent position on the sky. requires long baseline

Question 30

Stellar parallax

Answer 30

can be used to measure the distance between earth and a nearby star using the parallax formula.

Question 31

Ptolemy

Answer 31

first to carefully measure the motions of the planets. invented the epicycle.

Question 32

retrograde motion

Answer 32

when planets seem to change their direction in the sky and go backwards. planets move east, then loop back west, then east again.

Question 33

epicycle

Answer 33

made a good first approximation of retrograde motion. keeps perfect circles, constant speeds, and earth at center like Aristotle said.

Question 34

Copernicus

Answer 34

publishes a heliocentric model of the universe. explains retrograde motion. keeps Aristotle's idea of perfect circles and uniform motion.

Question 35

copernican revolution

Answer 35

the saying that we are not the center of the universe.

Question 36

Tycho Brahe

Answer 36

built the best observatory of its time to measure star and planet motions. discovered a supernova. realized heavens are not perfect and unchanging was unhappy w accuracy of planet predictions

Question 37

Johannes Kepler

Answer 37

used Tycho's data. empirically discovered 3 rules that accurately describes the true motions of the planets

Question 38

Kepler's Law #1

Answer 38

planets trace out ellipses with the sun at one focus

Question 39

eccentricity

Answer 39

how elongated the ellipse is

Question 40

Kepler's Law #2

Answer 40

planets sweep out equal areas in equal times. planets move faster when closer to the sun than further away. quantifies the speed of a planet on the elliptical orbit.

Question 41

perihelion

Answer 41

closest to the sun

Question 42

aphelion

Answer 42

furthest from the sun

Question 43

Kepler's Law #3

Answer 43

the orbital period of a planet, P, depends on its distance from the Sun, R P^2 = R^3

Question 44

newton's gravity

Answer 44

theory that explains the motion of the planets and how an apple falls from a tree

Question 45

fundamental theory - Noether

Answer 45

showed that conservation laws result from symmetries in nature. basis for modern particle physics. symmetries allow transformations that do not change the "system"

Question 46

Galileo Galilei

Answer 46

first real experimentalist observations help prove that the planets go around the sun. developed ideas of inertia and acceleration

Question 47

Galileo Gravity

Answer 47

Galileo supposedly tested the Aristotle idea that heavy objects fall faster than lighter ones. dropped 2 balls off tower of pisa. inclined planes and rolling balls. found all objects accelerated at the same rate due to gravity

Question 48

Galileo observations

Answer 48

craters and mountains in the moon sunspots phases of venus 4 moons around jupiter

Question 49

light as a wave

Answer 49

light waves are characterized by a wavelength (upside down Y) and a frequency f

Question 50

Spectroscopy

Answer 50

measure the temperature of the source measure the elemental composition of the source measure the velocity of the source

Question 51

continuous spectrum

Answer 51

light energy at all wavelengths. one way to make a continuous spectrum is thermal emission "Black body radiation" a way to measure the temperature of the stars

Question 52

emission lines

Answer 52

electron excited in an atom – decays to a lower energy state. emits light at a particular wavelength each element has its own unique set of electron energy levels

Question 53

absorption line spectrum

Answer 53

a continuous spectrum with gaps or dips at various wavelengths

Question 54

blackbody spectrum

Answer 54

depends on source temp. continuous, light energy at every wavelength everything with a temp emits blackbody radiation hotter=blue total energy goes up quickly with temp-T^4

Question 55

dark matter candidates

Answer 55

MACHO, WIMPS, MOND

Question 56

MACHO

Answer 56

massive astronomical compact halo object

Question 57

WIMPS

Answer 57

weakly interacting massive particle

Question 58

MOND

Answer 58

modified newtonian dynamics

Question 59

chromosphere

Answer 59

a thin layer of 10000ºK gas just above photosphere

Question 60

Photosphere

Answer 60

further in from Cromosphere, 5800ºK

Question 61

Corona

Answer 61

exact outside of sun. 1 million degrees

Question 62

sunspots

Answer 62

slightly cooler spots than the photosphere

Question 63

conduction

Answer 63

direct contact between cool and hot materials. not relevant in normal stars.

Question 64

radiation

Answer 64

light waves carry the energy

Question 65

convection

Answer 65

physical motion of hot material carrying the energy to cooler regions

Question 66

solar cycle

Answer 66

sunspot varies over 11 year cycle. magnetic polarity switches every other cycle.