HIST 3305 Lecture Notes - Lecture 4: Kukulkan, Mathematical Proof, Philolaus
NATS 1745: History of Astronomy- Exam Review
Chapter 1
1. What celestial event is New grange aligned to? Describe what happens at New
grange on this day.
New grange’s roofbox is aligned to the winter solstice sunrise. On the 21 of December
at sunrise, the hallway fills with a beam of light and is likely to reflect a belief in rebirth or
reincarnation.
2. Describe what happens to the Sundagger on the solstices and equinoxes.
At noon on the solstice and equinoxes, the sundagger exhibits 2 beams of sunlight,
which either bisect or frame the spirals depending on the equinox/ solstice
3. What celestial event is Stonehenge aligned to? Describe what happens at
Stonehenge on this day.
Stonehenge’s heel stone is aligned with the summer solstice, the sun rises behind the
heel stone perfectly, (due to the precision of the equinoxes
4. Why do archeoastronomers suspect that Stonehenge's Heel Stone had a
missing partner stone?
When Stonehenge was built the sun rose beside the heel stone, making us believe that
there were originally 2 heel stones to frame the sun
5. What causes the Sun to rise and set every day?
Due to Earth's 24-hour eastward-spin around its polar axis, the sun moves westward
across the sky, it rises in the east, reaches its highest point at noon, and then sets in the
west
6. What is the local time for an observer who is directly facing the opposite side
of the sky from Sun? What is the local time when the Sun is at its highest point in
the sky? What is the local time when the Sun is seen on the Eastern horizon?
What is the local time when the Sun is seen on the Western horizon?
- Local midnight
- Local noon for sun to be highest point
- Local sunrise
- Local sunset
7. What is the azimuth of the noon Sun in the northern hemisphere? How about
the southern hemisphere?
AZ in Northern = South
AZ in Southern = North
8. What does the word "solstice" mean? How does it describe what happens to
the Sun's rising and setting positions on the solstices?
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- The word solstice means - solar standstill
- The sun rising or setting position (the stop of that shift)
- Identifies the sun’s rising and setting positions on its northernmost and southernmost
positions.
9. What is the azimuth of sunrise and sunset on the Northern winter solstice?
How about the Northern summer solstice? How about the equinoxes?
Azimuth – direction along the horizon,
- Winter time - sun is mostly south, the winter solstice has to be SE for sunrise and SW
for the set
- Summer solstice (longer path), rising NE, setting NW
- Equinoxes (equal rise and setting) – rising E, setting W
10. Describe how the Thirteen Towers of Chankillo, Peru were used to track the
time of year. Given that this site is in the southern hemisphere, what is the
approximate azimuth (NE, SE, NW, SW) of the winter solstice marker? How about
the summer solstice marker?
Southern hemisphere
-Summer, rise SE, set SW
- Winter, rise NE, set NW
-13 tower s-the sun shifts through the notches and each interval between the towers
mark a month
- If you want to see sunrise you would have to cross to the E side of the hill
11. Which day is the longest day of the year, and why? Which day is the shortest
day of the year, and why? What are the lengths of daytime and nighttime on the
equinoxes?
- Summer Solstice (June 22): Sun rises and sets at its northernmost position, traversing
a long high arc (longest day, highest noon sun)
- Winter solstice (December 22): Sun rises and sets at its southernmost position,
traversing a short, low arc in the sky (shortest day of the year and lowest noon sun).
- Fall and Spring Equinox (Sept 23) (fall equinox) and (spring equinox) March 21): Sun
rises due E and sets due W, spending equal time above and below the horizon (equal
day and night)
12. What causes the seasons? Describe the orientation of the Earth relative to the
Sun during Northern summer. What season does the Southern hemisphere
experience at this time, and why?
- The seasonal changes is in the Sun's daily arc are due to Earth's 23.5 degrees tilt from
its orbit around the sun
- Northern Summer- the northern hemisphere is tilted towards the sun, the observer
sees the sun directly, it is higher in the sky and feels warmer because the light is more
concentrated
- Winter –the hemisphere is tilted away from the sun, sunlight hits indirectly (i.e. At an
angle), causing low arcs and less light per area, and less warmth
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13. Within what latitudes can an observer see the Sun directly overhead? How did
these latitudes get their names?
- Only within the Tropics can the sun be seen directly overhead (Tropic of Cancer) (N)
and Tropic of Capricorn (S) at noon.
- The Sun is in the Cancer constellation when the Sun is directly overhead (June
Solstice) in the Northern Hemisphere and the Sun is in the constellation of Capricorn
when the sun is directly overhead in the Southern hemisphere.
14. What are polar nights and polar days? Within what latitudes do these occur?
Polar nights – 24hrs of nighttime
Polar days – 24hrs of daylight
- They happen 23.5 degrees from the N/S poles
15. Where is the zenith? What is its altitude? What is the altitude of the horizon?
What is the altitude of a star that is halfway up the sky?
Where is the Zenith? - The point in the sky directly above you (1st question on the
exam), everybody has their own zenith it moves with you.
- The altitude of the Zenith - 90 degrees
- Altitude of horizon - 0 degrees
- Altitude of star half way up the sky - between 45 degrees
16. Does a star's altitude and azimuth depend on the observer's location? How
about right ascension and declination?
- Everybody has their own horizon, altitude and azimuth DOES depend on the
person's location
- Right ascension and declination (Longitude and latitude they are coordinates) DOES
NOT depend on your own location
17. If a star has a declination of 10 degrees north, what is the star 10 degrees
north from? If a star has a right ascension of 1h, what is the star 1h from?
- The star is 10 degrees North; it is 10 degrees north of the celestial equator
- The star is 1 hour away from the line that we call, the line of zero right ascension,
which marks the position at Spring Equinox
18. Where are we on Earth if we see the Northern constellations rotating around
our zenith? What is the name of the point that these stars rotate around? What
happens to this point if we walk south? Where is this point seen when we're at
the equator? Where is this point when we walk south of the equator?
- Northern Hemisphere
- North Celestial Pole
- The constellations would get lower
- The constellations would disappear into the horizon
- Southern Hemisphere
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Document Summary
Describe what happens at new grange on this day. New grange"s roofbox is aligned to the winter solstice sunrise. On the 21 of december at sunrise, the hallway fills with a beam of light and is likely to reflect a belief in rebirth or reincarnation: describe what happens to the sundagger on the solstices and equinoxes. Local noon for sun to be highest point. The word solstice means - solar standstill. The sun rising or setting position (the stop of that shift) Winter time - sun is mostly south, the winter solstice has to be se for sunrise and sw for the set. Summer solstice (longer path), rising ne, setting nw. Equinoxes (equal rise and setting) rising e, setting w: describe how the thirteen towers of chankillo, peru were used to track the time of year. 13 tower s-the sun shifts through the notches and each interval between the towers mark a month.
