Astronomy Test 3

11 (112) Even though observations of the sky were likely no more important than the surrounding landscape for ancient cultures, we feel that we can potentially learn more by studying how people observed the sky and how it influenced them. Explain why. (HW)

Landscapes changed and we only have indirect knowledge of what they looked like in the past, but we can reconstruct the past sky using what we know now. Being able to "see" this sky gives us insight into how ancient cultures were set up and how advanced they were.

20 (121) Explain how and why Johannes Kepler resolved the heliocentric vs geocentric debate for most scientists of his time. Kepler's model was very similar to that of Copernicus, but Kepler's was widely accepted while that of Copernicus was not. Explain why.

Kepler discovered three laws, elliptical orbits, equal areas equal times, and orbital period is proportional to distance, which proved that they do not orbit the Earth. He was able to make accurate predictions of planetary positions and so the people believed his laws. His model was widely accepted because he had actual proof, where Copernicus' model was just a theory.

8 (109) What does the winged disk symbolize in Egyptian architecture? What evidence tells us that the Egyptians used measurements along the horizon to keep track of the dates? (HW)

The winged disk symbolizes the Sun and its daily journey. It was seen as a bird flying through the sky. There was pottery with two peaks with images of the eastern and western Sun on either side. There are many depictions of two mountains between which the Sun rises and these are explained in Egyptian texts.

15 (116) "The more complex and accurate a calendar is, the more advanced is the culture that constructed that calendar." Explain the logical flaw in this statement. (HW)

There is a very wide range of reasons explaining ancient cultures' calendars. They could base their days and years after an animal or a single astronomical observation. We too often assume that they completely understood the meaning behind each part of their calendars.

4 (105) What did the crossed sticks symbolize to Mesoamerican? What evidence supports this interpretation of the crossed sticks? (HW)

They symbolized astronomical sightlines from temples. Starts could be seen through the V created by the sticks and there were drawings showing ancient sky watchers looking out the temple door through this V. Star glyphs often sit in the middle of this V. The star symbols seem to designate the temples as observatories.

17 (118) Some astronomers attempt to reconstruct sightlines that connect buildings to points on the horizon, such as prominent notches silhouetted in a distant mountain range. Explain the potential problem of this approach, why it may lead to incorrect conclusions. (HW)top left page 9

This can be a problem because not all ancient manmade structures were made to observe points along the horizon. Also, there weren't usually obvious landscape features in the direction of the solstice. Astronomers can simply assume something has an astronomical alignment and then base their observations and opinions based on what they now see.

6 (107) Describe the cosmology of the Aztec. Specifically, what were their "ages" and how did they end? How will our current age end, according to the Aztec, and how do we know this from carvings like the Aztec calendar stone? (HW)

Tonatiuh, the present Sun, was fifth in a line of Suns and each time one fell, the next would take its place. Each new Sun represented a new age. There was 4-Jaguar, 4-Wind, 4-Water, and 4-Movement. The current age will end in an earthquake and is shown by the face of an earth-lord on depicted on the calendar stone. The design represents movement, the current age, or earthquake.

19 (120) Explain Tycho Brahe's role in the debate between the geocentric and heliocentric models of the solar system.

Tycho wanted to make accurate maps of stars and planetary motions. He was a careful observer who was the first to compile high accuracy records of planetary motion including the outer planets. This led to his discovery of the lack of parallax and his support of the heliocentric model.

18 (119) What is a hierophany? Briefly describe two examples of hierophanies in Archaeoastronomy. (HW)

A hierophany is the playing of shadows and light in a sacred place. An example is Newgrange where after sunrise around the winter solstice the interior of the tomb is lit by the sunlight. Kukulcan is another example because a serpent's body appears on the staircase on days close to the equinoxes.

30 (131) Explain why the lifetime of a Beryllium-8 nucleus is an anthropic coincidence. How would the Universe be different if the lifetime of Be-8 were longer? Explain. What if its lifetime were shorter? Explain.

Beryllium 8 is an anthropic coincidence because its lifetime, 10 nanoseconds, is just enough for it to bond with Helium and form Carbon while not being too long. This seems to be just right in order for life to exist. If the lifetime was longer there would be a burst of carbon and the star would explode and we couldn't live. If its lifetime were shorter, we also wouldn't exist because we wouldn't have enough Carbon in our atmosphere because He and Be couldn't bond.

9 (110) Two of the most easily recognizable constellations that are up in the sky at this time of year are Canis Major and Orion. Find the following information and star chart about these two constellations: *diagram

Canis Major: 30 degrees S, Apha=Sirius, Beta=Murzim, Canis Major is the larger of Orion's hunting dogs seen behind him in the sky chasing the rabbit Lepus. Orion: 40 degrees SW, Alpha=Betelgeuse, Beta=Rigel, Orion's dad was Neptune and his mother was a great huntress and Amazon Queen from whom he acquired his hunting skills. He became very arrogant because he was the greatest hunter in the world, but a small scorpion stung and killed him.

12 (113) Explain what ethnocentrism is and briefly describe an example where this approach has been used in the field of archaeoastronomy and why this approach is flawed. (HW)

Ethnocentrism is putting one's own culture above others. In astronomy one may take an ancient observation and apply it to their culture and knowledge now. This is flawed because a more accurate account would be to approach the observation as viewed from the original people. In Ethiopia, a man determined the days between planting and harvesting by tying a knot in a cord worn around the ankle for each day. People were not impressed with his conclusions because it was irrelevant to their lives.

24 (125) Explain why Newton's Laws of gravity helped to solidify the foundation of Kepler's heliocentric model of the solar system.

He reproduced Kepler's laws mathematically to prove their accuracy. Newton proved his laws by using the same rules of gravity and force that are known to work on Earth. People believed this more because they could look at actual evidence.

27 (128) Explain how Hubble determined the distances to the "spiral nebulae" that were thought to be in our own galaxy. Explain how Hubble's findings were further confirmation of the Copernican Principle.

Hubble used the true brightness of the spiral nebulae compared to the apparent brightness to calculate the distance. He used their pulsation period to determine their brightness when he discovered Cepheid variables. This confirmed the Copernican Principle because he realized there were galaxies millions of light years away from our own and that we aren't the only one let alone the center.

14 (115) Not all apparent astronomical alignments are real and/or intentional. After all, everything has to point *somewhere*. Explain two ways we can distinguish between accidental and intentional astronomical alignments by describing the two examples (from Scotland and Central America) from the reading. (HW)

In Scotland there were stone circles with orientation relating to the moon. This orientation was repeated in both England and another part of Scotland showing the recurrence of this alignment. In Central America there was historical evidence to back up the alignments. Inscriptions or books would explain the purpose of the ancient astronomical observatories.

26 (127) Explain what Messier objects are. A particular kind of Messier object (globular clusters) is found most often in the direction of the sky near the constellation Sagittarius. What does this tell us about our position within the Milky Way galaxy?

Messier objects are the brightest objects in the sky that were repeatedly reported as comets. These were later found to be other galaxies or clusters of stars. Because the globular clusters are in the direction of Sagittarius we know that we are in the "suburbs" on the outer right part of the Milky Way galaxy.

22 (123) Explain why the apple falls from the tree but the Moon remains "suspended" in the sky, as Newton explained it.

Newton's law of gravity states that it does not just work on Earth, and that the force making the apple fall from the tree is the same force that makes the moon stay in the sky. The moon is moving fast enough that it simply orbits the Earth.

13 (114) Briefly explain two potential problems with using first-hand accounts to understand the ancient practices of a particular society. (HW)

One problem is that some information is sacred and therefore withheld, possibly leaving out important details that could change the meaning. Also, the ethnographer could influence the worldview and then a later investigator may think that it was firsthand knowledge.

23 (124) Given the equation of orbital velocity, explain how it is related to Kepler's 2nd Law, the law of "equal areas, equal times".

Orbital velocity has to do with how far away the object is from the Sun. If a planet is closer to the Sun it moves faster so it would cover a wedge and time that would equal part of the orbit when it's further from the Sun. In a 60 day time period a planet would cover a thicker wedge between its orbit and the Sun than 60 days on the opposite side of the orbit where the planet moves much slower; the areas of the two "wedges" would still be the same.

3 (104) Explain what parallax is. Given the parallax equation, be able to explain how we can measure the distance to some astronomical object (like the Moon) without actually having to travel there.

Parallax is the way that planets or other objects look with regards to the distance and background. Equation p= baseline/distance to object. We can measure the distance to other objects because we can already determine the baseline.

5 (106) What was patolli, and how is its design related to the designs seen in the Codices (such as Fejervary-Meyer and Madrid)? (HW)

Patolli is a game played by Mesoamericans. The board's design was organized cosmologically and relates to the 260 day calendar and 52 year round as did the Codices. They were also both set up around crosses and arcs.

21 (122) What are Kepler's three laws of planetary motion?

Planets have elliptical orbits, equal areas equal times, orbital period is proportional to distance.

7 (108) Explain the evidence that indicates that the early Babylonians were careful observers of Venus and aware of its cyclical motion through the sky. What is the possible reason given in the text that Venus was represented in drawings and on stones as an eight-pointed star? (HW)

References were found in an early Sumerian city on clay tablets showing symbols of the star Inanna, which is their word for Venus. Tablets were found showing goal-years in a pattern that predicted Venus would appear at the same position in the sky every eight years. The eight points could represent Venus' eight-year cycle.

16 (117) Explain why solstices were observed by more cultures while equinoxes were rarely observed. (HW)

Solstices are tangible, it marks the extreme that the sun can rise or set. This makes a four part natural division used in many cultures. Equinoxes on the other hand, are just in between the solstices and this midpoint doesn't seem as significant to ancient people. Equinoxes didn't help set the time like solstices did.

25 (126) What is the Copernican Principle? How is the success of the heliocentric hypothesis over the geocentric hypothesis representative of the success of this principle?

The Copernican Principle basically states that we are not special in the way that we are not the center of everything. The success of the heliocentric model supports this principle because it proved that the Sun is in fact the center not the Earth.

29 (130) Explain what the anthropic principle is. Also, what is an anthropic coincidence?

The anthropic principle is the idea that life is special. Many coincidences seem to happen so that life can exist. Because so many things match up just right to allow life to exist it supports the idea of it being special.

28 (129) Explain the faint sun paradox. How has the Earth managed to resolve this "paradox"?

The faint sun paradox has to do with the fact that the sun was about 30% fainter a long time ago and yet the Earth's temperature was about the same as it is now. The greenhouse effect tends to offset the brightness of the sun by trapping more or less gas as needed to regulate the Earth's temperature.

10 (111) Explain how attempts to observe parallax shifts in stars were used as evidence in support of the geocentric model. How does the heliocentric model of the solar system explain the lack of parallax shifts in stars?

The geocentric model says that the Earth does not move, and with observing parallax shifts in stars they were thinking that the stars were so far away that it seemed like they were surrounding the Earth, as if it was at the center of the universe. The heliocentric model says that the sun is at the center of the universe, and the lack in the shift of stars meant to them that they were moving around the same thing the Earth was, or the Sun. If the heliocentric model was used the 2 observations would have to be made 6 months apart where the baseline would be huge, making the parallax angle too small to measure. This led them to believe the distance to the stars was very big and it was too big for many of the astronomers at the time to believe.

1 (102) Explain the difference between the geocentric and heliocentric models for the solar system. In the geocentric model, explain what causes retrograde motion *diagram

The geocentric model says that the universe revolves around the Earth while the heliocentric model suggests the universe revolves around the Sun. The heliocentric model also makes it look like the faster planets are making the slower planets seem to move backwards. The geocentric model uses a system of epicycles to explain retrograde motion, whereby the planets moved around small circular paths that in turn moved around larger circular orbits around the Earth.

2 (103) Although the heliocentric model seems simpler and more logical in terms of successfully explaining retrograde motion, it was still not favored over the geocentric model even by the time of the 16th century, after Copernicus and Galileo began to influence thinking. Explain two reasons why, aside from the parallax argument.

The geocentric model was still favored because it was just as inaccurate and complicated and there was no actual proof that this model was correct. Also, people couldn't feel the Earth moving so they thought it couldn't possibly be moving around the Sun.