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NATS 1745 HISTORY OF ASTRONOMY > TEST 1 > Flashcards

TEST 1 Flashcards

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1
Q

List the cycles of the sky described in the lecture videos that have been obvious to skywatchers since ancient times

A

Apparent motion of the stars and planets, rising and setting patterns of the sun and moon, solstice and equinox

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2
Q

Prehistoric

A

before writing systems were invented by humans (approximately 5000 years ago and older)

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3
Q

Archaeoastronomy

A

the study of ancient sites and artifacts and their connections to the patterns in the day and night sky

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4
Q

What celestial event is Newgrange aligned to?

A

Winter Solstice

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5
Q

What is special about the Winter Solstice?

A

The day with the least amount of sunlight (aka the hottest day of the year)

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6
Q

What is significant about the days after the Winter Solstice?

A

The days after will be a little longer

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7
Q

Triskele

A

a common symbol throughout Celtic history, could represent life-death-rebirth

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8
Q

What happens at Newgrange during the Winter Solstice?

A

An alignment takes place for 17 minutes through a specially designed opening above the entrance called a roof-box, gradually illuminating the narrow passage

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9
Q

Kerbstone 52

A

Appears to show Orions belt and the star Sirius

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10
Q

When was Newgrange constructed?

A

~3200 BCE

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11
Q

When was Pueblo Bonito constructed?

A

between 850 and 1150 CE

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12
Q

Chaco Canyon Petroglyphs

A

two spirals that mark the annual solstices and equinoxes

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13
Q

What days and times of the year can the Sundagger be used to indicate?

A

Spring Equinox, Summer Solstice, Fall Equinox, Winter Solstice

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14
Q

What happens to the Sundagger in Spring and Fall Equinox?

A

Both spirals have the sun daggers in the centre

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15
Q

What happens to the Sundagger in the Summer Solstice?

A

Larger spiral has a sun dagger in the centre

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16
Q

What happens to the Sundagger in the Winter Solstice?

A

Two daggers on the sides of the large spiral

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17
Q

What celestial event is Stonehenge aligned to?

A

the sunrise of the summer solstice and the sunset of the winter solstice

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18
Q

What happens at Stonehenge during the Summer and Winter Solstice?

A

On the summer solstice, the sun rises behind the Heel Stone in the north-east part of the horizon and its first rays shine into the heart of Stonehenge. On the winter solstice, the sun sets to the south-west of the stone circle

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19
Q

Why do archaeo astronomers suspect that Stonehenge Heel Stone has a missing partner stone? 


A

when the Stonehenge was built, the rising sun on the Summer Solstice rose slightly to the left
They believe that there were two stones so that light would go in between and reach the centre region of Stonehenge.

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20
Q

What causes the Sun to rise in the east and set in the west every day?

A

The Sun rises in the east and sets in the west due to the Earth’s eastward rotation. If you’re facing east, the Earth’s rotation moves you in that direction, causing objects beyond the eastern horizon to appear as they rise. This daily movement of celestial objects is known as Diurnal Motion.

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21
Q

What is the longest day of the year?

A

Summer Solstice

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22
Q

Terminator

A

When we go into shadow aka night

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23
Q

Diurnal motion

A

the daily motion of the Sun, the stars, and other celestial bodies across the sky

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24
Q

Sun rises in the _____ and sets in the ______

A

East, West

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25
Q

The Earth spins from ______ towards ______

A

West, East

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26
Q

Which way does the Earth spin?

A

Clockwise

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27
Q

What does the word Equinox translate to?

A

Aequinoctium: awquus= equal and nox= night

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28
Q

Zenith

A

Place in sky right above head
90 degree altitude

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29
Q

What does the word Solstice translate to?

A

sol= Sun and sister= to stand still

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30
Q

Describe the Sun’s height & approximate direction (N, E, S or W) in the sky at NOON as seen from both the northern and southern hemisphere. 


A
  • In the Northern Hemisphere, people perceive the sun at its highest point in the Southern direction
  • In the Southern Hemisphere, people perceive the sun at its lowest point in the Northern direction
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30
Q

Describe the Sun’s height & approximate direction (N, E, S or W) in the sky at MIDNIGHT as seen from both the northern and southern hemisphere.

A
  • In the Northern Hemisphere, people face towards the midnight sun, and the sun does not set below the horizon. It is in the Northern direction
  • In the Southern Hemisphere, people face away from the midnight sun, and the sun does not set below the horizon. It is in the Southern direction
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31
Q

Describe the Sun’s height & approximate direction (N, E, S or W) in the sky at SUNSET as seen from both the northern and southern hemisphere.

A
  • In the Northern Hemisphere, the sun is at its lowest point and near
    the horizon. It sets in the Northwest direction
  • In the Southern Hemisphere, the sun is at its highest point and near the horizon. It sets in the Southwest direction
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32
Q

Describe the Sun’s height & approximate direction (N, E, S or W) in the sky at SUNRISE as seen from both the northern and southern hemisphere.

A
  • In the Northern Hemisphere, the sun is low at the horizon. The sun rises in the Northeast in the summer and rises in the Southeast in the winter
  • In the Southern Hemisphere, the sun is also low at the horizon. The sun rises in the Northeast in the winter and rises in the Southeast in the summer
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33
Q

What does the word “solstice” mean?

A

The word “solstice” means for the sun to stand still for a day

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34
Q

How does solstice describe what happens to the Sun’s rising and setting positions on the summer and winter solstices?

A

This describes the extreme points of the Sun’s path through the sky during these solstices.

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35
Q

Describe the difference between the Sun’s path through the sky on these 2 days

A

The key difference between summer and winter is Earth’s tilt. In summer, Earth is tilted toward the Sun, so sunlight is concentrated over a smaller area and the sun is highest. In winter, Earth is tilted away, causing the same amount of sunlight to spread over a larger area, making it less intense and the sun is lowest.

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36
Q

What are the lengths of daytime and nighttime on the equinoxes?

A

12 hours

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37
Q

What causes the seasons?

A

Earth’s tilted axis causes the seasons

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38
Q

Describe the orientation of the Earth relative to the Sun on the Summer Solstice

A

The summer solstice occurs when the Earth’s tilt toward the Sun is greatest, making it the longest day of the year for locations north of the Tropic of Cancer, with the Sun at its highest point in the sky

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39
Q

Describe the orientation of the Earth relative to the Sun on the Winter Solstice

A

Marks the shortest day and longest night of the year. In the Northern Hemisphere, it occurs when the sun is directly over the Tropic of Capricorn.

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40
Q

Describe the orientation of the Earth relative to the Sun on the Equinox

A

Equinoxes occur twice a year when the Earth’s axis is not tilted toward or away from the Sun, resulting in nearly equal daylight and darkness. Sunlight refraction causes this effect, and higher latitudes have slightly longer days due to slower sunrises and sunsets

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41
Q

Why does direct light feel warmer than indirect light?

A

Direct light feels warmer because it covers a small surface area, heat is concentrated and warmer, and the sun is high in the sky.
Indirect sunlight feels less warm because it covers a large surface area, heat is spread out and colder, and the sun is low in the sky.

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42
Q

What season does the Southern Hemisphere experience during Northern summer?

A

Winter

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43
Q

Why does the Southern Hemisphere experience winter during Northern summer?

A

The Southern Hemisphere tilts away from the Sun, receiving angled rays, while the Northern Hemisphere tilts toward the Sun, causing summer there

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44
Q

What is the latitude of the equator?

A

0 degrees

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45
Q

What is the latitude of the North and South pole?

A

90 degrees North and 90 degrees South

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46
Q

Within what latitudes can an observer see the Sun directly overhead? How did these latitudes get their names?

A

23.5 degrees
Capricorn and Cancer
They got their names from the Greek/ Babylonian constellations

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47
Q

What are polar nights?

A

Polar nights occur in the northernmost and southernmost parts of the planet when there is night for more than 24 continuous hours

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48
Q

What are polar days?

A

Polar days occur when the sun stays above the horizon for more than 24 continuous hours

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49
Q

What happens to the number of polar days and nights as you get closer to one of Earth’s poles?

A

The close to the North Pole the longer the night which means more polar nights

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50
Q

Where is the zenith and what is its altitude?

A

the point in the sky directly above the observer
90 degrees

51
Q

Where is the horizon and what is its altitude?

A

the circle that divides a person’s visible sky from the invisible sky
0 degrees altitude

52
Q

What is the altitude of the Sun when it is halfway up the sky?

A

The sun’s altitude is 45 degrees when it is halfway up the sky

53
Q

What is the Sun’s altitude if you can fit 3 fists in between the horizon and the Sun’s position in the sky?

A

The sun’s altitude is 30 degree

54
Q

Given that the Moon’s angular length is 0.5°, what fraction of the width of your finger would span the length of the Moon?

A

It would be ½ of the width of finger

55
Q

Does the Sun’s
altitude and azimuth depend on the observer’s location?

A

Yes because an object’s altitude and azimuth angles shift as you move to a different spot on the Earth’s surface

56
Q

What 2 features of the Pyramid of Kukulkan tell us that the Maya had deciphered
the solar cycle?

A
  1. The pyramid has four staircases with 91 steps each, plus a top step, adding up to 365 steps, representing the days in a year
  2. During the equinoxes, the pyramid creates a shadow pattern resembling a serpent, which aligns with the serpent head at the base, symbolizing their awareness of the sun’s position at different times of the year
57
Q

What was El Caracol likely used for, and how do we know this?

A

a round building that was used like an observatory and to get a view of the entire horizon. The windows in the observation room aligned to the N-most and S-most setting positions of planet Venus

58
Q

Briefly describe the origin of the belief that the world was going to end on Dec 21, 2012

A

The Mayan’s long calendar was finite, ending with the 13th baktun, which marked the completion of a cycle. On Dec 21st, the count reached 13.0.0.0.0, signifying the end of one cycle
it covered a 5,000 year period, ending on December 21, 2012

59
Q

What physical proof do we have that the Maya tracked eclipses and the planet
Venus?

A

The Dresden Codex was the Mayans bark book that contains 30 year’s worth of tracking of Venus and 100 years of predictions of eclipses

60
Q

What was it about the Mayan number system that facilitated their ability to find patterns in their numeric records of the events in the sky?

A

They used dots and lines, a simple and visual way to represent numbers, making it easy to perform calculations and track astronomical cycles.

61
Q

What causes the Moon’s phases?

A

our view of the sunlit side visible to us (the side facing the sun), which changes the moon’s appearance for us on Earth.

62
Q

What is a lunation?

A

One complete cycle of the moon phases (29.5 days)

62
Q

State the 8 phases of the Moon, in order of appearance, starting from New Moon

A
  1. Full moon – directly whole sunlit side facing us
  2. Waning gibbous – moon sunlit side (on left side) is decreasing from a full circle
  3. 3rd quarter phrase (Quarter moon) - ½ lit up and ½ is not, we are only seeing ¼ of the moon.
  4. Waning crescent – ¾ of circle of moon facing us is dark, ¼ is lit up by sun on the left
  5. New moon - (about 15 days after full moon) – the moon is completely dark to us, the unlit portion is facing earth.
  6. Waxing crescent – lit portion starting to increase towards a full moon, lit up on the right side (based on our relative position on earth).
  7. 1st quarter moon (Quarter moon) – seen after a new moon, sunlit portion lit up on the right.
  8. Waxing gibbous – sunlit portion increasing towards full on right side of moon towards full moon.
63
Q

What is the difference between a waxing and waning moon?

A

Waning= decreasing sunlit side visible to us, from the full moon towards the new moon
Waxing= increasing sunlit side visible to us from the new moon towards the full moon

64
Q

If we look at the moon on a given night, how can we tell if it is waxing or waning?

A

If the lit up portion is on the right side of us, it is waxing moon. If it is on the left, it is waning moon.

65
Q

Why are crescent moons seen primarily during the day? Why are gibbous and full moons seen primarily at night?

A

Crescent moons are seen near the sun and mostly during the day. As the moon approaches the new phase, it’s more visible in daylight. Quarter moons are visible half in the day, half at night. As the moon nears full, it becomes more visible at night, with a full moon appearing only at night.

66
Q

Why did many ancient civilizations believe that eclipses are bad omens as well as unpredictable?

A

Eclipses are unpredictable due to their long cycles (18 years) and are seen as bad omens because they feel unnatural. A lunar eclipse turns the moon red, and a solar eclipse causes sudden darkness, disrupting the natural light, which is vital for life, making the experience unsettling.

67
Q

What is the cause of a solar eclipse? What is the Moon’s phase when this happens?

A

A solar eclipse happens when a new moon casts its shadow on Earth. A moon must be in its new phase, and the shadow must reach the Earth’s surface

68
Q

Describe the appearance of a total solar eclipse and a partial solar eclipse.

A

In a total solar eclipse, the moon completely covers the sun, leaving only a ring of light visible.
In a partial solar eclipse, the sun appears partially covered, with the extent depending on your proximity to the umbra (the moon’s shadow).

69
Q

If an observer sees a total solar eclipse, where is this observer standing? Where is an observer standing if they see a partial solar eclipse? What will the Sun look like if you are standing outside the umbra and penumbra during a solar eclipse.

A

Total: umbra
Partial: penumbra
If standing outside the umbra and penumbra during a solar eclipse: nothing

70
Q

What is the cause of a lunar eclipse? What is the Moon’s phase when this happens?

A

Occurs when a full moon enters Earth’s shadow and the moon has to be full

71
Q

Describe the appearance of a total lunar eclipse

A

the moon turns red as it is fully covered by the Earths shadow

72
Q

Describe the appearance of a penumbral lunar eclipse

A

causes only a faint dimming, making it barely noticeable.

73
Q

Describe the appearance of a partial lunar eclipse

A

shows part of the moon in shadow, with its appearance depending on the extent of coverage

74
Q

If a total lunar eclipse is seen, what is the Moon passing through?

A

the moon is passing through the Earth’s umbra

75
Q

If a partial lunar eclipse is seen, what is the Moon passing through?

A

the moon is passing partially through the umbra, but not completely, so it spends a lot of time in the penumbra.

76
Q

If a penumbral eclipse is seen, what is the Moon passing through?

A

the moon is passing through the penumbra

77
Q

If an observer on the night side of Earth witnesses a total lunar eclipse, will all observers on the night side of Earth see a total lunar eclipse at the same time?

A

Yes, they will because Earth is casting the shadow on the moon and everyone will be able to see this on the night side since it is not location dependent, you just need to be in the night

78
Q

Why don’t eclipses occur every New and Full moon?

A

The moon’s orbit is tilted by 5 degrees, so during most new and full moons, it’s either slightly above or below Earth’s shadow. Eclipses only happen when the new moon aligns directly with the sun or the full moon aligns with Earth.

79
Q

What do we call the time period when eclipses can occur? On average, how many lunation’s are there between these time periods? Why are there always at least 1 (or 2) solar eclipses and 1 (or 2) lunar eclipses during these time periods?

A

An eclipse season
6 lunation’s between the eclipse seasons
There are 29.5 days in a lunation period whereas there are 31-38 days in an eclipse season. Hence, eclipses may occur at least twice a year.

80
Q

Why are lunar eclipses seen more frequently than solar eclipses?

A

It is because to see a solar eclipse, one must be within the umbra or penumbra. However, to see a lunar eclipse, you only need to be on the night side of the Earth

81
Q

Describe the evidence in the Mayan Dresden codex that tells us that the Maya understood the eclipse cycle and were able to predict, for eternity, the dates on which eclipses would occur.

A

The numbers 177 and 148, found at the bottom of all 8 pages, represent the approximate time between eclipse seasons, calculated from lunations
The Mayan were able to predict when multiple eclipses would occur, using Tzolk’in dates to accurately forecast eclipses. They recorded cumulative days since eclipse observations, reaching up to 11,960 days before the table repeated.

82
Q

Why did the Maya believe that they had occasionally prevented an eclipse by worshiping the Sun and Moon God?

A

If the Maya didn’t witness an eclipse on Tzolk’in dates, they believed their prayers had appeased the Sun and Moon gods, as they thought eclipses happened when the gods were angry or fighting.

83
Q

What 2 characteristics of the planet Venus caused the Mayans to identify it as a special kind of star?

A

It was the brightest ‘star’ on the night sky visible to the Mayans. It was also a ‘wandering’ star in that it changed its position against the background stars.

84
Q

What is a heliacal rise of Venus, and how does Venus appear when this occurs? According to Mayan legend, why was this event an important day of Mayan worship?

A

Heliacal rise of Venus is when it reappears in our morning sky, is at its brightest, and rises with the sun. It was important because the Mayan’s depicted god Kukulkan as the planet Venus.

85
Q

When is Venus seen (morning or evening) during the ~8-month period after its bright heliacal rise? Is it getting brighter or dimmer, and why? Why does it disappear after this period? When it finally reappears, is it a morning or evening star? For the next ~8 months, is it getting brighter or dimmer? Why does it disappear again after this period, before its next heliacal rise?

A

Can be seen in the morning. Gets dimmer because Venus gets further away from earth in its orbit. After this period, Venus is hidden behind the Sun (hence it disappears). Reappears as an evening star.Gets brighter then. It disappears for a week after because of inferior conjunction (venus’ dark side faces the Earth).

86
Q

Describe the evidence in the Mayan Dresden codex that tells us that the Mayans understood the Venus cycle and were able to predict, for eternity, the dates on which the appearances and disappearances of Venus would occur.

A

The Dresden Codex details Venus’s cycle, noting 236 days for its helical rise and 90 days for its disappearance. Row 4 of the Tzolk’in dates contains the exact dates of this cycle.

87
Q

According to historians, what was it about climate conditions in the region of Ancient Babylon that motivated the Babylonians to study the sky?

A

The region of Babylon did not have a reliable source of rainfall, which made it harder to grow crops. Hence, babylonians studied the sky in hopes that they could predict the weather.

88
Q

Why are there so many ’60s’ in our units for time and angle?

A

Babylonians used a base 60 in their numeric system as 60 has many factors, and has less fractions. We inherited that from the babylonians and that is evident in how we measure time and a full circle.

89
Q

For Mercury what aspect of their appearance was used to choose the Babylonian/Greek god to name it?

A

speedy scribe/messenger god; due to fast motion
o Babylonian – Nabu, god of wisdom and writing
o Greek/Roman - Mercury/Hermes, messenger god

90
Q
A
91
Q

For Venus what aspect of their appearance was used to choose the Babylonian/Greek god to name it?

A

Goddess of love/beauty; due to its brightness (closest planet to Earth)
o Babylonian – Ishtar, goddess of love
o Greek/Roman- Aphrodite, goddess of love

92
Q

For Mars what aspect of their appearance was used to choose the Babylonian/Greek god to name it?

A

God of war/bloodshed; due to its red colour (soil compose of iron + oxygen/water = rust)
o Roman - Mars, god of war.
o Greek - Aries, god of war.
o Babylonian - Nergal, god of war.

93
Q

For Jupiter what aspect of their appearance was used to choose the Babylonian/Greek god to name it?

A

2nd brightest in the sky, Father of the Gods; due to its brightness and majestic (slow/stately) motion (biggest in size)
o Babylonian – Marduk, the supreme god
o Greek/Roman – Zeus/Jupiter, King of gods

94
Q

For Saturn what aspect of their appearance was used to choose the Babylonian/Greek god to name it?

A

God of old age; due to its faintness and slow motion (nearly as big as Jupiter and much further away, double the distance of Jupiter to us)
o Babylonian – Ninurta, farmer god
o Greek/Roman – Kronos/Saturn, good of old age/god of harvest

95
Q

Why do the stars move across the sky throughout the night?

A

As the earth spins, the stars appear to rotate around the North Celestial Pole. From the southern hemisphere, the stars appear to rotate around the South Celestial Pole.

96
Q

Suppose we are standing on Earth’s North pole, what are the stars moving around, and where in the sky is their centre of rotation? What happens to this point if we travel toward the equator?

A

The stars are moving around the North Celestial Pole (NCP) Centre of rotation is Polaris - the north star if you’re in the northern hemisphere, NCP gets lower and lower to the sky if we travel towards the equator.

97
Q

When standing on the equator, how will the stars appear to move if we face north? How about if we face south? What will happen to the centre of the Southern stars’ rotation if we travel south of the equator?

A

When standing at the equator the stars appear to be towards the horizon and setting west. For the south it will be the same image as the north but upside as things are flipped. If you travel south of the equator everything will start to rise higher in the sky.

98
Q

What objects (if any) mark the North and South Celestial Poles?

A

The north pole has Polaris known as the north star and sits almost where the north pole sits in space. The south pole does not have a star that sits by the south pole, to find the south celestial pole, but they use magellan cloud to find the south celestial pole.

99
Q

In the Northern hemisphere, how can we use a star to determine our latitude on Earth?

A

An observer’s latitude corresponds to the altitude of the visible celestial pole; as latitude increases, the celestial pole appears higher in the sky. Polaris’s altitude equals your latitude. You can estimate your latitude by extending your fist at arm’s length, where each fist stacked represents 10 degrees.

100
Q

Why do we see different stars and constellations at different times of the year?

A

We see different constellations and stars at different times of the year due to the earth’s annual orbit around the Sun.

101
Q

How is it possible to use a star to determine when 1 year has elapsed?

A

When a star/constellation returns to its normal position, we know that1 year has elapsed, or 365.24 days.

102
Q

What was the primary motivation for studying the sky in Ancient Egypt?

A

The primary reason the ancient Egyptians studied the sky was to predict when the Nile river was going to flood.

103
Q

Why was the star Sirius used to mark the beginning of a new year?

A

Sirius heliacal rise was marked as the beginning of the new year because as a coincidence it aligned with the annual flooding of the Nile river. The ancient Egyptian saw Sirius above the horizon before sunrise before the flooding would happen.

104
Q

Why did the Ancient Egyptians divide the day into 24 hours?

A

The ancient Egyptians divided the day into 24 hours, observing 12 constellations that rose at night and set before sunrise, along with 12 that rose during the day and set at sunset. This cycle of rising and setting defined their 24-hour clock.

105
Q

Why do we add a leap day every 4 years? Who incorporated this rule into our calendar, and from what civilization did he learn this rule?

A

We add a leap year every 4 years to add up to 365 days for the year. Pope Gregory X111 incorporated this rule because too much time was being added.

106
Q

Why do we now use the Gregorian calendar instead of the Julian calendar?

A

We use the Gregorian calendar instead because there was too much time in the Julian calendar. Also, the Gregorian calendar would stop a leap year or a leap day from happening and would keep things on track.

107
Q

Where are the zodiac constellations?

A

Capricorn(us), Aquarius, Pisces, Aries, Taurus, Gemini, Cancer, Leo,Virgo, Libra, Scorpio(us), Ophiuchus, Sagittarius.

108
Q

Why were Zodiac constellations significant to the Babylonian astrologers?

A

The zodiac constellations were important to the Babylonians because their gods were believed to travel through them. The grouping of stars was significant to their beliefs, as associating the sun, moon, and planets with these gods influenced how they lived and understood the world.

109
Q

Why can we not see our astrological constellation in the month we were born?

A

During your birth month, the Sun’s position in the sky aligns with your zodiac constellation, making it invisible due to the Sun’s brightness

110
Q

Why have our zodiac signs changed since their original definitions by the Ancient Greeks?

A

Due to the procession of the equinox, the zodiac constellation rotates in the sky and will align again in 26,000 years.

111
Q

According to historians, what was it about the ancient Greek empire that made it possible for theories about natural science, and astronomy in articular, to progress further than in other ancient civilizations

A

It progressed because of the region’s fragmented geography and decentralized rule. They had more ability and time to think and intellectual freedom. They established higher places for learning and argued to understand the universe.

112
Q

What does a geocentric cosmology refer to?

A

refers to all celestial bodies orbiting around the fixed Earth at the centre.

113
Q

What does a heliocentric cosmology refer to?

A

refers to all celestial bodies including Earth revolving around the Sun at the centre

114
Q

How would geocentric cosmology explain the daily cycle of the Sun and the stars?

A

Geocentric cosmology explains how the Sun revolves around the Earth once a day and stars orbit the Earth once every year.

115
Q

How would heliocentric cosmology explain the daily cycle of the Sun and the stars?

A

Heliocentric cosmology explains how the Earth revolvesaround the Sun, and stars or all celestial bodies revolve around the Sun annually.

116
Q

Why is Thales called one of the “original scientists”? According to legend, what celestial event did Thales successfully predict in order to prove his philosophy?

A

Thales sought explanations for natural phenomena that did not involve the gods and took a scientific approach. Thales successfully predicted the eclipse in order to prove his philosophy.

117
Q

Describe (very generally) the features of Anaximander’s cosmology and how it explained some of the cycles of the sky.

A

Anaximander’s cosmology pictured Earth as a floating cylinder in space, surrounded by rings with the sun and moon orbiting around it. He explained day and night by the sun and moon’s movement, and a cylinder of stars also moved around the Earth.

118
Q

What was Pythagoras proposing when he called the Universe a “cosmos”?

A

he was proposing that the universe follows comprehensible mathematical laws & all cycles of nature could be predicted by mathematical equations. It was a harmonies system and ordered system.

119
Q

What did Pythagoras propose about the shape of planetary orbits? What did he propose about the shape of the Earth?

A

Pythagoras proposed that all planetary orbits including Earth were perfectly circular and believed that circle was the purest geometric shape.

120
Q

Describe 3 observations that support the Pythagorean hypothesis about the shape of the Earth.

A

1) Ships gradually disappear on the horizon bottom first.

2) Earth’s shadow on the eclipsed moon is always round.

3) When you travel North or South, the constellations rise and set more rapidly than they would have if the earth was flat

121
Q

What did Philolaus believe about the Earth? What did this belief explain about the sky?

A

He believed that the earth rotates once a day around a central fire that’s not the sun. This belief explained the daily motion of celestial bodies in the sky.

122
Q

What did Herakleides believe about the Earth, and what caused him to propose a different theory than Philolaus’?

A

Herakleides believed that there is no evidence of “central fire”, the earth spins once a day around its own axis which would explain the daily motion of the sky.

123
Q

What did Herakleides believe about the motion of Mercury and Venus, and why?

A

Herakleides believed that Mercury and Venus orbited around the sun; he used this explanation as an answer as to why their motion and brightness changes.

124
Q

What two measurements are Aristarchus famous for?

A

Aristarchus was famous for methods of measuring the distance and size of the moon and Sun.

125
Q
A

NATS 1745 HISTORY OF ASTRONOMY (2 decks)

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