NATS 1745 Exam chapter 1
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celestial event is Newgrange aligned to? Describe what happens at Newgrange on
- Newgrange’s roof box is aligned
- to the winter solstice sunrise.
- A beam of sunlight hits the roof-box and
- illuminates the floor, which will eventually illuminate the main chamber.
- As sun rises, a light of beam
- through roof-box
what happens to the Sundagger on the solstices and equinoxes.
- At the winter and summer
- solstice, and rise also at the equinoxes, sunlight shines between three giant
- rocks at the summit of Fajada Butte, throwing bright “sundaggers” onto an
- intricate set of spiral patterns carved on the rock behind
What celestial event is Stonehenge aligned
to? Describe what happens at Stonehenge on this day.
- Stonehenge is most likely an
- observatory for following the sun through the seasons. It is a monumental
- shrine to the sun. Stonehenge’s heel stone is aligned to the summer solstice
- sunrise. The sun rises just over the heel stone position of the monument on the
- summer solstice.
Why do archeoastronomers suspect that
Stonehenge's Heel Stone had a missing partner stone?
- The sun used to hit right next
- to the Heel Stone and that didn’t make sense
- Also it was the only stone that
- was by itself when all other stones in the Stonehenge were in pairs
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, then sets in the west.
. What is the local time for an observer
who is directly facing the opposite side of the sky from Sun?
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?
is the azimuth of the noon Sun in the northern hemisphere? How about the
- Northern Hemisphere its due
- Southern Hemisphere its due
- *The reason being is because
- the sun's daily arc in the Northern Hemisphere is shifted towards the south.
- The noon sun means that the sun is at its highest point in the sky and it also
- means our location is directly facing the sun's direction.That's why its due
- south. "Due" meaning exact.
- Apply that same concept to the
- Southern Hemisphere. The sun's daily arc is shifted towards the North. Once
- again, the noon sun is at its highest point in the sky and it also means the
- southern hemisphere's location is directly facing the sun's direction.That
- explain's due north for them
What does the word "solstice"
mean? How does it describe what happens to the Sun's rising and setting
positions on the solstices?
- The word means solar stand
- The sun itself never stands
- still but what we are referring to by the stand still is the rising and the
- setting position
- The sun rises at different
- location on the sky everyday
- When it stops shifting south
- the stoppage of the shifting
is the azimuth of sunrise and sunset on the Northern winter solstice? How about
the Northern summer solstice? How about the equinoxes?
- for the winter solstice, NE and
- summer solstice, its SE
- winter solstice: SE, SW. summer
- solstice: NE, NW. equinox: E, W
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
- On the midwinter solstice, the
- Sun rises behind the leftmost tower of the 13 that makes up the newly
- discovered solar observatory of Chankillo in Peru. During the next 6 months, it
- rises behind all the others in turn. In
- the S- hemisphere, the Sun’s daily arc point N- rather than S.
- Remember, dealing with South,
- which means Winter Solstice Sun is rising NE and Sun setting NW. one of them
- will be t NE . Sunrise -> points NE. Sunset -> points NW
- SE, and SW marked by furthest
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?
- Longest day of the year is the
- Summer Solstice
- It's because the sun travels
- its highest, longest arc which means it’ll be at its highest point in the sky
- and it'll spend the most amount of time above its horizon compared to other
- daily arcs that it travels throughout the year
- Shortest day of the year is the
- Winter Solstice
- the equinoxes : equal day and night
- A. Summer Solstice (June 22):
- Sun rises and sets at its northernmost position, traversing a long high arc
- (longest day, highest noon sun) b. 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). c. 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)
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 seasons are caused by the
- tilt of the Earth’s rotational axis away or toward the sun, as it travels
- through its year- long path around the sun.
- Earth is oriented more toward
- the sun
- winter ?, opposite end, thus
- less sun?
Within what latitudes can an observer see
the Sun directly overhead? How did these latitudes get their names?
- Only within the tropic of
- cancer and capricon
- Tropic Cancer because if you
- stay at this latitude, on the day of June solstice, and noon, the sun is in the
- cancer constellation when it hits the Zenith
- And tropic of capricorn, and
- the definition is similar -> if you stand there when sun hits top of sky in
- december solstice, noon sun is in capricorn constellation.
are polar nights and polar days? Within what latitudes do these occur?
- Polar nights -> 24 hours of
- darkens inside the polar circles
- Polar days - the midnight sun
- Polar days and Polar nights
- occur within 23.5 degrees from the poles in both the artic and antartic
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?
- It is a point in the sky that
- is directly above you
- The altitude of the zenith 90
- The altitude of the horizon is
- And a star half way up is 45
Does a star’s altitude and azimuth depend
on the observer’s location? How about right ascension and declination?
- Altitude depends on horizon so
- the altitude and azimuth does depend on observer’s location
- No the ascension and
- declination does not depend on a person’s location they are absolute
. 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?
- Matter of remembering
- definition of declination (What is the definition of declination)
- Right ascension is just one
- hour away from the line it is one hour away from the right ascension line that
- marks the summer equinox
- the celestial equator. the line
- of zero right ascension, which is marked by the Sun's position on the Spring
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?
- We are at the north pole
- The north celestial pole
- It is going to get lower and
- lower in the sky
- It is going to be pointing
- We are not going to be able to
- see it anymore
an observer sees Polaris at an altitude of 60 degrees, what is the observer’s
- Latitude is equal to the
- altitude of the polaris
celestial object did the Polynesians use as the basis of their calendar? What
does this object consist of? How did the Polynesians use this object to
identify the 1st half and 2nd half of their calendar year? In ancient times,
how was this object used in the Andes to determine when to plant?
- Pleides which are a group of
- stars in the sky in that area
- The first half started in
- December, when they saw the Pleiades rising as the Sun set
- The second half started in May
- or June, when the Pleiades were first visible in the morning sky
What did the Polynesian navigators memorize
in order to steer their canoes while at sea?
- What they memorized was the
- rising and setting stars
- They memorized a star compass.
- It divided the horizon up into 32 different directions, corresponding to the
- rising or setting of individual bright stars and the all- important Pleiades.
- Basically, they relied on the stars.
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