Assignment
NATs 1745: Midterm Exam Review - Chapters 1-2
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University:
York University -
Course:
NATs 1745 | History of Astronomy Academic year:
2023
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Views:
261
Pages:
7
Author:
Nick T.
EXAM REVIEW Chapters 1-2
Chapter 1:
efine archaeoastronomy and list the cycles of the sky that have always been easily
D
observable and predictable.
rchaeoastronomy:The study of ancient sites and howpeople in the past have understood
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the phenomenon in the sky and its cycles.
Easily observable cycles of the sky include:
● Mid-Summer
● Spring and Fall Equinox
● Mid-Winter
escribe the ancient sites discussed in this lesson, their relationship with the Sun,
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and how their solar alignment appears to visitors of the site.
. N
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ewgrange
- Large stone tomb comprised of a Roofbox that is aligned with the winter solstice
sunrise
- On this day a beam of sunlight hits the Roofbox and illuminates the floor
- This civilization believed in some form of reincarnation- Rebirth
. S
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undagger of Chaco Canyon
- Through the canyon are rock formations (One called Fajada Butte)
- The summer solstice is the only day of the year when the ‘dagger of light’ perfectly
cuts through the spiral carving
- Theorized to be a sun shrine to worship the sun on these special days
. S
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tonehedge
- Ring of stones
- On the summer solstice, while inside the stone structure, the sun will rise the heel
stone.
- Stonehenge was likely used for ancient rituals tied to the sun rising/setting behind
specific stones.
escribe the daily cycle of the Sun’s path in the sky and explain its cause. Given the
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time of day and the Sun’s direction (N, SE, etc), identify the location of an observer on
Earth relative to the Sun as well as the observer’s hemisphere.
The Sun’s path in the sky:
Due to Earth's 24-hour eastward spin, the Sun moves westward across the sky.
● Rising east, setting west
-hemisphere:The Sun is mostly seen in the southernsky, reaching due south (exact
N
south) at noon.
S-hemisphere: The Sun is mostly seen in the northernsky, reaching due north (exact
north) at noon. Timezones:defined by the Sun's position in the sky relative to your location.
escribe the annual cycle of the Sun’s path in the sky and explain its cause, including
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the meaning of the solstices and the equinoxes and the Earth’s orientation on those
special days. Use this understanding to:
● m
ake predictions about the Sun’s location in the sky at a given time of day and
time of year
● d
escribe how to design a site with an alignment to the solstices & equinoxes
(ie, how would you identify the directions of the rising & setting sun on those
days?)
quinox:Latin for Equal Night
E
Solstice:Solar Standstill (Sun reached its furthestpoint north and south)
On the Northern Hemisphere:
all & Spring Equinox: sunrise is due E, sunset isdue W; equal day & night
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Winter Solstice: Sun rises and sets at its southernmostpoints; travels a short, low arc
On the S-hemisphere:The sun's daily path arcs towardN rather than S
rediction:Identifying the Sun's rising/setting positionson the solstices simply requires
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finding its N-most & S-most positions
esigned site:Make a notch in the ground that pointsto each sunrise position.Observe the
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sun rising and setting for 365 days in one spot. After you would see the S-easternmost notch
point to the winter solstice sunrise and the N-easternmost notch point to the summer solstice
sunrise. Then the notch that is marked in the middle will mark the Fall/Spring Equinox.
xplain why Earth experiences seasonal changes, including why this experience
E
changes depending on the observer’s hemisphere. Use this understanding to make
predictions about seasonal conditions on a planet with a different tilt than Earth’s
S
●
easons change due to Earth's 23.5° tilt.
● Winter occurswhen the hemisphere is tilted away fromthe sun.Summer occurs
when the hemisphere is tilted towards the sun.
efine the meaning of latitude and the special reference latitudes that have a
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connection with the Sun. Describe how the Sun’s path in the sky varies with latitude
and use this to explain the meaning of polar days and polar nights. Use this
understanding to make predictions about where polar days, polar nights, and the
tropics would be experienced on a planet with a different tilt than Earth’s.
Latitude (L):a location's angle N or S of Earth'sequator
● The lower your latitude, the higher the Sun's daily paths and therefore the warmer the
temperature ● P
olar daysandpolar nightsonly occur within Arctic& Antarctic Circle; the higher the
latitude, the more polar days/nights
efine the reference points and lines on the celestial sphere and describe the location
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of an object in the sky using its altitude and azimuth. Use this understanding to
explain why altitude and azimuth are relative coordinates.
elestial Sphere:our view of the sky projected ontoan imaginary sphere to describe the
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positions of celestial bodies.
Reference points - specific to each observer
orizon:the circle around an observer that separatesthe visible and invisible hemispheres
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of the sky.
** Zenith:the point in the sky directly above theobserver.**
To describe the location of a celestial body in the sky is by using the:
. a
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ltitude:the object's angle upward from the horizon
2. azimuth:the object's direction along the horizon
- Since they are angles up and along the horizon they are relative coordinates
Express angular sizes and distances in the sky using your hands and fingers.
Angular unitsare used to measure objects in the sky
_________________________________________________________________________
Chapter 2:
For the two ancient civilizations discussed in this lesson:
● explain their general motivations for tracking the sky (ie, what their
astronomical records used for)
● describe their astronomical sites and/or record-keeping artifacts discussed in
this lesson and what each was used for
● identify the main feature of each of their written number systems that
facilitated their ability to identify the celestial cycles . T
1
he Mayan Civilization
● They tracked/predicted sky cycles to seek favour from the gods associated with
celestial bodies. (Worship)
● The Pyramid of Kukulclan
- 365 steps (Shows the awareness of the Sun’s annual cycle)
- Annual patterns of light and shade track the time of year
● El Caracol (Observatory):Tracked Venus cycles insky
● D
resden Codex (Bark Book):containing historical eventsand tables of celestial
cycles
ayan Numbers:Were visually represented, making iteasy to add and subtract large
M
numbers. Allowed Maya to identify patterns in the intervals between celestial events.
. T
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he Babylonian Civilization
● Babylonians tracked celestial cycles because they believed the sky foretold the
future.
● Ruins on walls containing tablets:were used to tracknightly sky logs and data
abylonian numbers:Their number system used the baseof 60 which has a lot of factors.
B
This allowed them to record information easily. (We adopted units multiple of 60)
xplain the origin of the misconception that the Maya predicted the end of the world
E
on Dec 21, 2021.
● M
ayan calendar notation ended on December 21, 2012, raising mistaken fears that
this heralded the end of time
● In truth, Mayan records describe this date as the last date of one calendar cycle, as
opposed to the last date of all time
Define lunation, state its length, and explain the cause of the Moon’s phase changes.
Lunation:one complete cycle of moon phases (29.5days)
● The moon phases are due to our changing view of the moon's sunlight side
The more of the moon
●
that is illuminated, the more of a
nighttime moon it is.
● Same the the other way Explain why solar and lunar eclipses were a common fear among ancient civilizations
● In ancient times, eclipses were seen as bad s due to the diminishing appearance of
the Sun/Moon & perceived unpredictability.
escribe the cause and appearance of solar and lunar eclipses, including the different
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types of each eclipse (penumbral, partial, etc.) and the orientation of the Sun, Moon,
and Earth during each type. Apply this knowledge to identify whether the appearance
of each type of eclipse is location-depended or not, and explain why lunar eclipses
are witnessed more often the solar eclipses
olar eclipse:occurs when the New Moon casts itsshadow on Earth
S
- total:seen from parts of Earth in the Moon's primaryshadow (umbra)
- partial:seen from parts of Earth in the Moon'ssecondary shadow (penumbra)
(location-depended)- depends if you are in the moon umbra or not
unar eclipse:occurs when a Full Moon passes throughEarth's shadow
L
- penumbral:Moon passes through Earth's penumbra
- partial:part of the Moon passes through Earth'sumbra
- total:entire Moon passes through Earth's umbra
(Not location-depended) - We all see the same moon
efine an eclipse season, state its length and average frequency, and explain the
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cause of its cycle.
● E
clipses can only occur when the Moon is New/Full and the Earth-Moon-Sun are
coplanar
● Due to the tilt of the Moon's orbit, coplanarity only occurs 2-3 times per year and lasts
31-38 days (eclipses seasons)
ow the Mayan eclipse tables were used, and why the Maya believed they
H
occasionally prevented an eclipse.
T
●
he tables were used to record dates of eclipses to then predict future eclipses.
● Whenever an eclipse was not seen on their predicted dates the Maya believed that
the sun and the moon gods were satisfied by their sacrifices. (Eclipses are not seen
every 6-5 lunations.)
Why is it sometimes possible for 2 eclipses to occur in the same eclipse season
● If an eclipse season starts on a new or full moon you will get either 2 lunar or solar
eclipses.
xplain the importance of the planet Venus to the Maya, and why it is so easily
E
recognizable in the night sky. ● A
war hero named Kukucan mysteriously disappeared into the mountains. The planet
Venus rose at the same spot in the mountains where he disappeared. They believed
Venus embodied Kukucan
● Next to the Moon, Venus is the brightest object in the night sky
Define heliacal rise and describe the cycle of Venus, including its length and how the
planet’s time of visibility, as well as its appearance, changes throughout its cycle.
Apply this knowledge to explain how the Mayan Venus records were used.
eliacal Rise:The first visible rising of a celestialobject in the morning sky after conjunction
H
with the Sun.
The cycle of Venus: Is a 584 day cycle
. Inferior Conjunction:Venus's dark side faces Earth.(invisible)
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2. Helical Rise:After a week venus reappears as a morningstar. (The first appearance
is brightest)
3. Moving further away from Earth, gradually getting dimmer
4. After about 8 monthsSuperior Conjunctiontakes place.Venus is hidden by the
sun.
5. After 3 months of Superior Conjunction, Venus reappears as an evening star. (The
first appearance is dimmest)
6. Over the next 8 months, Venus will be seen after sunset, getting brighter gradually.
(getting closer to Earth)
7. Then when it reaches its brightest points it disappears and the cycle repeats.
Mayan Venus records contained:
● Kukuclan defined as Venus
● The # of days and dates between Venus appearance and disappearance
or each of the visible planets, describe the key feature(s) of their appearance which
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led to their chosen name.
.
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2.
3.
4.
5.
ercury:speedy scribe/messenger god; due to fastmotion
M
Venus:goddess of love/beauty; due to its brightness
Mars: god of war/bloodshed, due to its red color
Jupiter:father of the gods; due to its brightnessand majestic motion
Saturn: god of old age; due to its faintness and slowmotion
escribe the daily cycle of the stars, and how the stars’ paths change depending on
D
the direction the observer is looking as well as the observer’s latitude. Apply this
knowledge to explain how, in the Northern hemisphere, we can use a star to
determine our latitude on Earth.
● A
s Earth spins daily, the stars appear to rotate around
the North and South Celestial Poles
● They always rise east and set west ● A
n observer's latitude is given by the altitude of the visible celestial pole (the higher
the latitude, the higher the Pole
Explain why we see different stars and constellations at different times of the year.
● Due to Earth's annual orbit, the visible stars/constellations change each night
xplain the significance of the star Sirius to the Ancient Egyptians, and how this star
E
was used as a calendar
● The heliacal rise of Sirius (the brightest star in the sky) coincided with Nile's annual
flood and was therefore used to mark the New Year
xplain the origin of the following calendrical elements:
E
- the 24-hour day
● Egyptians tracked time at night using 12 constellations when used at roughly equal
intervals, which led to a 24-hour day
- the 60-minute hour and the 60-second minute
● Babylonian Number system of a base of 60.
- the leap day
● Ptolemy IllI added another leap day every 4 years
- the Julian calendar
● The Julian calendar was created to address inconsistencies in tracking time,
introducing a leap day every four years to better match the solar year.
- the Gregorian calendar
● The Gregorian calendar was then developed to refine leap-year’s 11.5 min error.
tate the location of the zodiac constellations and explain their significance to the
S
Babylonian astrologers:
odiac constellations are located along the ecliptic(the path of the Sun, and planets);
Z
used for making astrological predictions
xplain the astronomical meaning of your zodiac sign and why our zodiac signs have
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changed since their original definitions by the Ancient Greeks.
Y
●
our zodiac sign is the Sun's constellation in the month you were born
● Sun's monthly constellations have shifted since the zodiac signs were assigned
~3000 years ago (due to precession of the equinoxes)
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