Ancient Skywatching Study Guide PDF

Unit 1: Ancient Skywatching of the Sun Study Guide 1. Introduction to archaeoastronomy: a. List the cycles of the sky described in the lecture videos that have been obvious to skywatchers since ancient times. - The sun’s day/ night cycle Takes 24hrs to repeat Everyday fo...

Unit 1: Ancient Skywatching of the Sun Study Guide 1. Introduction to archaeoastronomy: a. List the cycles of the sky described in the lecture videos that have been obvious to skywatchers since ancient times. - The sun’s day/ night cycle Takes 24hrs to repeat Everyday for thousands of years the sun has rose in the east and set in the west - The day/ night cycle of the stars When the sun goes down the stars also rise in the east and set in the west - Every month annually the sun is changing its highest point - Lunar cycle or moon phases Every month the moon is not only changing its position from west to east in the span of 4 weeks it is also changing what it looks like as it does that. b. What is archaeoastronomy? - Archaeoastronomy is defined as the study of ancient sites and artifacts and their connections to the patterns in the day and night sky 2. Newgrange: a. What celestial event is Newgrange aligned to? What is special about this day of the year, and the days that follow it? Describe what happens at Newgrange on this day. Newgrange is aligned with the rising sun on the winter solstice. The winter solstice is a significant astronomical event with several special characteristics including: Its the day with the least amount of sunlight and the shortest day of the year, the sun is at its lowest position in the sky, and the sun sets at its most south-west point and rises at its most south-east point. On the days following the winter solstice many things also happen: the sun starts rising again, symbolizing rebirth, every day after the winter solstice, the sun’s path goes back up, the sun’s rising position gradually moves northward, and daylight hours begin to increase. On the winter solstice at newgrange the rising sun shines directly along the passage into the chamber for 17 minutes illuminating the chamber floor. The sunlight enters through a specially built opening called the roof box. This alignment is believed to have been intentional, connecting to celtic beliefs about life, death and rebirth. 3. The Sundagger of Chaco Canyon: a. What days and times of the year can the Sundagger be used to indicate? Describe what happens to the Sundagger on these days and times. - Winter solstice During this time, the sun casts a shadow that aligns with the spiral but is shorter and more confined Light goes through both cracks - Summer solstice (Longest day) On this day, the sunlight creates a sharp, elongated shadow that precisely aligns with the spiral At noon when the sun is the highest in the sky Sunlight goes through only one crack Leaves long dagger of light - Spring Equinox Two daggers appear, one on each of the swirly petroglyphs - Fall Equinox Similar to spring equinox, two daggers appear 4. Stonehenge: a. What celestial event is Stonehenge aligned to? Describe what happens at Stonehenge on this day, in the 21st century. Stonehenge is located at Salisbury, United Kingdom. Stonehenge is aligned with the summer solstice, which is the longest day of the year. On this day a significant celestial event occurs at stonehenge: On this day, the sun rises directly over the Heel Stone, creating a stunning sight as it appears to rise above the ancient stones. In the 21st century, the summer solstice at Stonehenge attracts large crowds, including druids, pagans, and tourists. Many people gather to celebrate the event with rituals, music, and dancing, embracing the spiritual significance of the solstice. The atmosphere is festive, with visitors often dressed in traditional attire. As the sun rises, many participate in ceremonies, marking the longest day of the year and the start of summer. b. Why do archaeoastronomers suspect that Stonehenge's Heel Stone had a missing partner stone? Some Archaeoastronomers believe that stonehenge’s heel stone originally had a partner stone, that when the original structure was built, they had two heel stone set in the direction of the rising sun so that when the sun came up on the summer solstice these two stones perfectly framed the sun. But as the years went on and all the stones were taken or even moved, one of these two heel stones was moved and no one knows where it is. They believe in this theory for the following reasons: - Due to the procession of the equinoxes the sun’s rising position has slightly changed over thousands of years. This shift makes it appear as if the sun was meant to rise directly above the remaining heel stone, rather than its original position beside it. Other lesser theories that were not include in the lecture so may not be on the test: - Alignment with the Sun: The Heel Stone is positioned to mark the sunrise on the summer solstice. The symmetry of the site suggests that a matching stone would enhance this alignment. - Stone Arrangement: The layout of the stones at Stonehenge indicates a deliberate design. The presence of one Heel Stone implies that the builders may have intended to create a symmetrical entrance, which would likely include a counterpart. - Historical Accounts: Some historical texts and archaeological studies reference a second stone in the alignment, leading researchers to believe that it might have existed. - Archaeological Evidence: Investigations in the area have uncovered potential remnants or disturbances in the ground where a second stone may have stood. 5. The Sun’s daily cycle: a. What causes the Sun to rise in the east and set in the west every day? The sun rises in the east and gets to the highest point (noon) and sets in the west. This is caused by the earth’s rotation not by the sun’s actual movement. The earth is is a sphere that spins around it north-south axis every 24 hours. The earth rotates counterclockwise, from west to east. This rotation makes it appear as if everything in the sky, including the sun, is moving from east to west. So while it looks like the sun is moving across the sky, it is actually earth’s rotation that creates this illusion. And this pattern repeats daily, with the sun rising in the east and setting in the west, and has been occurring for thousands of years. b. Describe the Sun’s height & approximate direction (N, E, S or W) in the sky at noon, sunset, midnight & sunrise, as seen from both the northern and southern hemisphere. The sun goes through a daily cycle that consists of it rising in the east, reaching its highest point at noon, and setting in the west. This apparent motion is caused by the earth’s rotation on its north-south axis every 24. |From the northern hemisphere the sun mostly appears in the southern half of the sky, so when looking north the sun appears to move from right to left (east to west). Front he southern hemisphere the sun mostly appears in the northern half of the sky, so the sun’s path is still east to west but occurs on the northern side of the sky. Key points: - The sun always rises in the east and sets in the west regardless of hemisphere - The sun’s position depends on your latitude, time of day,and time of year - This daily motion of the sun and starts across the sky ius called diurnal motion 6. The Sun’s annual cycle: a. What does the word "solstice" mean? How does it describe what happens to the Sun's rising and setting positions on the summer and winter solstices? The word solstice translates from the latin words “sol” = sun and “sistere” = ‘to stand still’. Solstice literally means “sun standing still”. It describes how the sun appears to pause in its journey north or south before reversing direction. - On the winter solstice the sun rises at its most south-east and sets at its most south-west position. The sun stands still and the day is very short ( It is the shortest day of the year). - On the summer solstice the sun has moved to its highest position in the sky (higest point north-east) and sets at its most north-west position. It “stands still” at its highest point before starting to move back down. b. Which day is the longest day of the year? Which day is the shortest day of the year? Describe the difference between the Sun’s path through the sky on these 2 days. Use this to explain the 2 reasons that summertime is warmer than Wintertime. The longest day of the year is when the sun is at its highest position in the sky. This is the summer solstice. The winter solstice is the shortest day of the year, when the sun is at its lowest position in the sky. The difference between the sun’s path on these two days is that, during the summer solstice, the sun's path is long and high, providing more daylight, while during the winter solstice, the path is short and low, resulting in less daylight. Two reason’s that summertime is warmer than wintertime: 1. Longer Daylight Hours: During the summer, the longer duration of sunlight, means the sun spends more time above the horizon and allows for more time for the Earth's surface to absorb heat, resulting in warmer temperatures. In contrast, shorter daylight hours in winter mean less time for warming. 2. More Direct Sunlight: The higher angle of the sun during summer leads to more concentrated sunlight hitting the Earth's surface, increasing warmth. In winter, the sun's low angle results in sunlight being spread over a larger area, reducing its intensity and warmth. c. What are the lengths of day time and night time on the equinoxes? On equinoxes the lengths of daytime and nighttime are equal. We get about 12 hours of day and 12 hours night. This leads to equal day and equal night which is called an equinox. Note: The word “equinox” comes from the latin word “aequinoctium” meaning “equal” and “nox” meaning ‘night’ Why this happens? Because the sun is rising exactly east and setting exactly west the sun spends about half the day above the horizon and half the day below the horizon so we get 12 hours of day and 12 hours of night, leading to equal day and night (equinox) d. On the two diagrams below, you should be able to determine: the hemisphere of the Earth (north or south) that each diagram represents which daily path of the Sun (A, B, or C) corresponds to the summer solstice, winter solstice & equinoxes, and the months in which they occur. the Sun’s rising, setting, & noon position on each path the direction the Sun is travelling on each of the daily pathways Let’s analyze the two diagrams to determine the hemisphere, solstice/equinox paths, and the Sun’s movement: 1. Identifying the Hemisphere: In both diagrams, the Sun follows different paths (A, B, and C) at various times of the year. The Sun moves higher in the sky during summer and lower in winter. Diagram 1: The Sun reaches its highest point (Path A) when it is farthest to the left, indicating northward sunrise. This suggests the diagram represents the Northern Hemisphere. Diagram 2: The highest point (Path A) aligns more towards the right, indicating southward sunrise, which matches the Southern Hemisphere. 2. Solstices, Equinoxes, and Paths (A, B, C): Path A (Highest Path): Summer Solstice: June 21 in the Northern Hemisphere (Diagram 1) December 21 in the Southern Hemisphere (Diagram 2) Sunrise: Earliest Sunset: Latest Sun's Noon Position: High in the sky Path B (Middle Path): Equinoxes: March 21 (Vernal) and September 23 (Autumnal) in both hemispheres Sunrise and Sunset: Due east and west, respectively Noon Position: Midway Path C (Lowest Path): Winter Solstice: December 21 in the Northern Hemisphere (Diagram 1) June 21 in the Southern Hemisphere (Diagram 2) Sunrise: Latest Sunset: Earliest Sun’s Noon Position: Low in the sky 3. Sun’s Movement and Direction: Diagram 1 (Northern Hemisphere): Summer Solstice (Path A): Sunrise: Northeast Sunset: Northwest Direction of Movement: Arcs from east to west through the southern sky Winter Solstice (Path C): Sunrise: Southeast Sunset: Southwest Equinoxes (Path B): Sunrise: Due east Sunset: Due west Diagram 2 (Southern Hemisphere): Summer Solstice (Path A): Sunrise: Southeast Sunset: Southwest Winter Solstice (Path C): Sunrise: Northeast Sunset: Northwest Equinoxes (Path B): Sunrise: Due east Sunset: Due west e. For each position in the diagram below, you should be able to determine: The solstice or equinox that each position of the Earth corresponds to, both in the northern and southern hemisphere The local time at the position of each observer 1. Solstices and Equinoxes at Each Position Top-left position (Northern Hemisphere tilted toward the Sun) Event: Summer Solstice in the Northern Hemisphere (June 21). Northern Hemisphere: Longest day of the year. Southern Hemisphere: Winter Solstice – shortest day of the year. Season: Northern Hemisphere: Summer Southern Hemisphere: Winter Top-right position (Earth’s tilt is neither toward nor away from the Sun) Event: Autumnal Equinox in the Northern Hemisphere (September 23). Both Hemispheres: Day and night are roughly equal (12 hours each). Season: Northern Hemisphere: Autumn (Fall) Southern Hemisphere: Spring Bottom-right position (Southern Hemisphere tilted toward the Sun) Event: Winter Solstice in the Northern Hemisphere (December 21). Northern Hemisphere: Shortest day of the year. Southern Hemisphere: Summer Solstice – longest day of the year. Season: Northern Hemisphere: Winter Southern Hemisphere: Summer Bottom-left position (Earth’s tilt is neutral) Event: Vernal Equinox in the Northern Hemisphere (March 21). Both Hemispheres: Day and night are equal (12 hours each). Season: Northern Hemisphere: Spring Southern Hemisphere: Autumn 2. Local Time at Each Position (Observer’s Perspective) Top-left: If the observer is on the equator, noon will occur when the Sun is directly overhead. On the Northern Hemisphere's summer solstice, observers at the North Pole experience 24 hours of daylight. Top-right (Autumnal Equinox): At all latitudes, day and night are nearly equal in duration (12 hours each). Local noon occurs when the Sun reaches its highest point in the sky. Bottom-right (Winter Solstice): In the Northern Hemisphere, the Sun rises later and sets earlier, resulting in shorter daylight hours. Observers at the North Pole experience 24 hours of darkness. Bottom-left (Vernal Equinox): Like the autumnal equinox, day and night are equal everywhere. Local noon will be at the Sun's peak, with 12 hours of daylight and 12 hours of night across the globe. 7. The cause of seasons: a. What causes the seasons? Describe the orientation of the Earth relative to the Sun on the solstices and equinoxes. The seasons are caused by the earth’s axial tilt and its orbit around the sun. The earth’s axis is tilted 23.5 degrees relative to its plane. This tilt remains fixed, always pointing at polaris (the north star) regardless of where the earth is around the sun. Because the earth is fixed and is always pointing at the same direction, as we go around the sun our view of the sun changes. This tilt means that different parts of the Earth receive varying amounts of sunlight throughout the year. As the Earth orbits the sun over the course of a year, the orientation of its tilt remains relatively constant in relation to the sun. This results in different hemispheres experiencing varying degrees of sunlight at different times: - Equinoxes Spring and Autumn (or Fall) occur during the equinoxes, when the tilt is such that both hemispheres receive roughly equal amounts of sunlight, leading to nearly equal day and night lengths. The earth is not tilted towards or away from the sun On the autumn equinox the sun will be hitting earth in such a way that its night time will perfectly hit where the north pole is and where the south pole is- directly chopping the earth in half along the axis - Summer solstice Sun is at its highest point Northern Hemisphere: The North Pole is tilted toward the Sun, resulting in the longest day of the year. Sunlight strikes this hemisphere more directly. Marks the beginning of summer in the northern hemisphere. The northern hemisphere gets more direct sunlight when the north pole is tilted towards the sun Southern Hemisphere: The South Pole is tilted away from the Sun, resulting in the shortest day of the year. - Winter solstice The sun is at its lowest point The north pole is tilted away from the sun Marks the beginning of winter int he northern hemisphere Northern Hemisphere: The North Pole is tilted away from the Sun, leading to the shortest day of the year with less direct sunlight. Southern Hemisphere: The South Pole is tilted toward the Sun, resulting in the longest day of the year. The changing orientation of the earth’s axis relative to the sun throughout its orbit causes the seasons by affecting the amount and directness of sunlight received in different hemispheres. b. Why does direct light feel warmer than indirect light? Direct sunlight feels warmer than indirect sunlight due to 2 main factors: 1. Concentration of light: Direct sunlight is more concentrated, focusing on the sun’s power in a smaller area. The concentration of energy results in more heat being absorbed by surfaces exposed to direct sunlight. 2. Path through atmosphere: Direct sunlight travels through less atmosphere, retaining more of its energy. Indirect sunlight, especially near the horizon, passes through more atmosphere (about 400km vs 100 km for overhead sunlight). As sunlight travels through more atmosphere, more of its energy is scattered, particularly blue light. According to the internet: Direct light feels warmer than indirect light due to several factors: Intensity of Light: Direct sunlight is more intense because it travels in straight lines and hits a surface more directly, concentrating energy in a smaller area. This means more energy is transferred to your skin or any surface it hits. Absorption: When light strikes a surface directly, that surface absorbs more energy. This absorbed energy is converted into heat, which raises the temperature of the surface and, in turn, warms the surrounding air. Scattering of Light: Indirect light, such as light that is reflected or scattered (like on a cloudy day or in shaded areas), has to travel further and is diffused across a larger area. This results in less intensity and energy reaching any given spot, making it feel cooler. Angle of Incidence: The angle at which sunlight strikes a surface also affects how much heat is absorbed. Direct sunlight typically strikes the surface at a more perpendicular angle, maximizing absorption, whereas indirect light strikes at a more oblique angle, leading to more reflection and less heat absorption. c. What season does the Southern Hemisphere experience during Northern summer, and why? During the northern hemisphere’s summer the southern hemisphere experiences winter. This occurs due to the earth’s axial tilt. The earth has a fixed axial tilt that remains constant as it orbits the sun. When the north pole is tilted towards the sun, it results in: - Summer in the northern hemisphere - Winter int he southern hemisphere This tilt causes differences in direct sunlight: - The northern hemisphere gets more direct sunlight when tilted towards the sun - The southern hemisphere receives less direct sunlight during this time As a result the seasons are opposite in the two hemispheres: - When its summer in the north, its winter in the south - The southern hemisphere gets colder weather when the northern hemisphere experiences warmer temperatures. 8. The Sun and latitude: a. What is the latitude of the equator? What is the latitude of the North and South Pole? - The equator has a latitude of 0° - The north pole has a latitude of 90° North - The south pole has a latitude of 90° South These latitudes represent key points on earth’s coordinate system: - The equator is the natural dividing line between the northern and southern hemisphere - The Poles represent the extreme northern and southern points on the planet - Latitude is measured in degrees north or south of the equator, with the poles being the maximum possible values b. Within what latitudes can an observer see the Sun directly overhead? How did these latitudes get their names? Latitudes where the sun can be directly overhead: - 23.5° North (Tropic of Cancer) (June summer solstice) - 23.5° South (Tropic of Capricorn) (December winter solstice) Origin of names: - Tropic of cancer: Named because on the summer solstice the sun appears to be in the direction of cancer - Tropic of capricorn: Named because on the winter solstice, the sun appears to be in the direction of the constellation Capricorn For locations between these latitudes, the sun can be directly overhead on specific days of the year. For locations outside of these latitudes (e.g., mid-latitudes like toronto), the sun is never directly overhead. c. What are polar nights and polar days? Within what latitudes do these occur? What happens to the number of polar days and nights as you get closer to one of Earth’s poles? Polar Days (Midnight Sun): - Polar days occur during the summer months in regions within the Arctic and Antarctic Circles. In these areas, the sun remains above the horizon for 24 hours, resulting in continuous daylight for an extended period. (In simple words it is periods of 24 hours of continuous sunlight). Polar Nights: - Polar nights occur during the winter months when the sun remains below the horizon for 24 hours, resulting in complete darkness or twilight conditions for an extended period. (Periods of 24 hours of continuous darkness) Latitudes Involved: - These phenomena occur within the arctic and antarctic circles. The arctic circle is a specific latitude created by the earth’s axial tilt. - Arctic Circle: Approximately 66.5° N latitude. - Antarctic Circle: Approximately 66.5° S latitude. Changes with Proximity to the Poles: As you get closer to either pole (North or South), the duration and frequency of polar days and nights increase: - At the Arctic and Antarctic Circles: You will experience one day of continuous daylight (polar day) and one night of continuous darkness (polar night) each year. - Closer to the Poles: As you approach the North Pole (90° N) or South Pole (90° S), the duration of polar days and nights lengthens. For example, at the North Pole, the sun is continuously above the horizon for six months during the summer (6 months of continuous daylight) and continuously below the horizon for six months during the winter (6 months of continuous night). - At the equator no polar days or nights In summary, the phenomenon of polar days and nights becomes more pronounced as you get closer to the poles, leading to extreme variations in daylight and darkness throughout the year. 9. The celestial sphere: a. Where is the zenith and what is its altitude? Where is the horizon and what is its Altitude? - Zenith is the point in the sky directly above an observer’s head. It is local to each individual, meaning everyone has a different zenith due to their physical location. The Zenith is 90° in altitude. - The horizon is the line where the Earth's surface and the sky appear to meet. It is the farthest point you can see in any direction from your viewpoint, and its position depends on your elevation above sea level. It has an altitude of 0°. It is 90° away from the zenith in any direction (N,S,E,W). - Altitude measures how high something is above the horizon. It ranges from 0° (horizon) to 90° (zenith) b. What is the altitude of the Sun when it is halfway up the sky? Does the Sun’s altitude and azimuth depend on the observer's location? Explain. When the Sun is halfway up the sky, it is at an altitude of 45 degrees. This position occurs when the Sun is at its zenith point between rising and setting, meaning it is halfway from the horizon to its highest point in the sky. Altitude and azimuth form a coordinate plane used to precisely point out things in the sky, downside is that it is specific to time as the objects in the sky move) Altitude is how high something is above the horizon Azimuth is the direction (Basic directions of N,S,E,W) Yes, the Sun’s altitude and azimuth do depend significantly on the observer's location for several reasons: - In the northern hemisphere, the sun mostly appears in the southern half of the sky while in the southern hemisphere, the sun is on the northern half of the sky. This shows that the location of the sun on the sky is dependant on where you are on the planet. Reasons according the the internet: - Latitude: The altitude of the Sun at solar noon varies by latitude. For example, at the equator, the Sun can be directly overhead (90 degrees) during the equinoxes, while at higher latitudes, the maximum altitude at noon will be lower.  - Time of Year: The Sun's position changes with the seasons due to the tilt of the Earth's axis. During summer in one hemisphere, the Sun will reach a higher altitude at noon compared to winter. - Time of Day: The azimuth (the compass direction from which the sunlight is coming) also changes throughout the day as the Earth rotates. At sunrise, the Sun has an azimuth near 90 degrees (east), and at sunset, it is around 270 degrees (west). 10. Describing lengths in the sky: a. What is the Sun’s altitude if you can fit 3 fists in between the horizon and the Sun’s position in the sky? One hand held at arms length is approx. 10° wide If you can fit 3 fists between the horizon nd the sun’s position, that would be equivalent to 3 x 10 = 30 degrees Therefore the sun’s altitude in this scenario would be approx. 30 degrees above the horizon. b. 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? - The moon’s angular length is 0.5 degrees - A finger held at arms length spans approx. 1 degree in the sky Therefore the moon would span half the width of your finger when held at arm’s length. This is because the moon’s 0.5-degree angular size is exactly half of the 1 degree span of a finger at arms length.  Unit 2: Ancient Skywatching and the Moon, Planets, and Stars: Study Guide 1. Introduction to Mayan Astronomy: a. What 2 features of the Pyramid of Kukulkan tell us that the Maya had deciphered the solar cycle? The Pyramid of Kukulkan, also known as El Castillo, at Chichen Itza showcases several features that indicate the Maya had a deep understanding of the solar cycle: - The Step Design: The pyramid consists of 91 steps on each of its four sides, totaling 364 steps, plus the top platform, which brings the total to 365. This design reflects the number of days in the solar year, demonstrating the Maya's knowledge of the solar calendar. - Shadow Play During the Equinoxes: During the spring and autumn equinoxes, the setting sun casts shadows on the northwest side of the pyramid that create the illusion of a serpent descending the steps. This phenomenon symbolizes the return of Kukulkan, the feathered serpent deity, highlighting the importance of solar events in their culture and calendar. Together, these features illustrate the Maya's advanced understanding of solar cycles and their significance in their astronomical and religious practices. b. What was El Caracol likely used for, and how do we know this? El Caracol, located at the Chichen Itza site, was likely used as an astronomical observatory. We know this because: The structure is unique because of its round shape and the windows that are aligned in all directions. These windows are thought to have been specifically designed to track celestial bodies, particularly Venus. The Mayans had a deep interest in Venus, and one of the windows points toward the northernmost setting position of Venus. The building's alignment with the planet’s cycle, which lasts 584 days, indicates a sophisticated understanding of the sky. This knowledge comes from the intentional design of the windows and the alignment of the structure with Venus' movement. 2. Mayan Record Keeping: a. Briefly describe the origin of the belief that the world was going to end on Dec 21, 2012. The belief that the world was going to end on December 21, 2012, originated from a misinterpretation of the Mayan Long Count calendar. This calendar, used by the Mayans, had multiple cycles, and one of them, called the 13th Baktun, was set to end on December 21, 2012. A baktun is a period of 144,000 days, and the completion of the 13th Baktun marked the end of a significant cycle in the Mayan calendar. However, the Mayans did not predict the end of the world; rather, it was simply the conclusion of that specific cycle, after which a new cycle would begin. The misunderstanding came from the idea that the end of the calendar implied the end of the world b. What physical proof do we have that the Maya tracked eclipses and the planet Venus? The physical proof that the Maya tracked eclipses and the planet Venus comes from their written records, particularly the Dresden Codex. This codex, made from durable bark paper, contains extensive astronomical information, including over 400 months’ worth of eclipse predictions (spanning 34 years) and 100 years of tracking Venus' cycle. The accuracy of these records, which are still valid today, shows the Maya's deep understanding of the sky. Additionally, structures like El Caracol were designed with alignments specifically to observe Venus, further confirming their tracking of the planet​ c. 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? The Mayan number system facilitated their ability to find patterns in their numeric records of sky events due to its complexity and flexibility. It was a highly advanced system, featuring a base-20 (vigesimal) structure that allowed for detailed and large-scale calculations. This system enabled them to record and track celestial events, such as the cycles of the moon, eclipses, and Venus' movements, over long periods. Their complex mathematics, supported by logograms (pictorial symbols), helped them accurately track and predict astronomical patterns, which they documented in their codices 3. The Moon’s Phases: a. What causes the Moon's phases? The Moon's phases are caused by the changing angles between the Earth, Moon, and Sun as the Moon orbits the Earth. As the Moon moves around Earth, the portion of the Moon illuminated by the Sun changes. We see different amounts of this illuminated portion, resulting in the phases. The entire cycle takes about 29.5 days, known as a lunation. When the Moon is between the Earth and Sun, we see the new moon (none of the illuminated side). As it moves, more of the illuminated side becomes visible, leading to phases like waxing crescent, first quarter, and full moon​ b. What is a lunation? A lunation is the period it takes for the Moon to complete one full cycle of its phases, from new moon to new moon. This cycle lasts approximately 29.5 days. During a lunation, the Moon goes through all its phases, including new moon, waxing crescent, first quarter, full moon, and waning phases​ c. State the 8 phases of the Moon, in order of appearance, starting from New Moon. New Moon – The Moon is between the Earth and Sun, and the side facing Earth is not illuminated, so it is invisible from Earth. Waxing Crescent – A small, crescent-shaped portion of the Moon's right side begins to be illuminated as it grows (waxing). First Quarter – Half of the Moon’s right side is illuminated and visible from Earth; it is one-quarter of the way through its cycle. Waxing Gibbous – More than half of the Moon’s right side is illuminated, continuing to grow toward full illumination. Full Moon – The entire side of the Moon facing Earth is fully illuminated by the Sun. Waning Gibbous – The illuminated portion begins to shrink (wane), with more than half of the left side still lit. Third Quarter (Last Quarter) – Half of the Moon’s left side is illuminated, marking three-quarters of the way through its cycle. Waning Crescent – A small crescent of the left side is illuminated as the Moon approaches the end of its cycle d. What is the difference between a waxing and waning moon? If we look at the moon on a given night, how can we tell if it is waxing or waning? - The difference between a waxing and waning moon lies in the amount of the Moon's illuminated portion visible from Earth. - A waxing moon occurs when the illuminated portion of the Moon is increasing, moving from New Moon to Full Moon. - A waning moon occurs when the illuminated portion is decreasing, moving from Full Moon back to New Moon. - To tell if the Moon is waxing or waning on a given night: If the right side of the Moon is illuminated, it is waxing (growing). If the left side of the Moon is illuminated, it is waning (shrinking)​ e. Why are crescent moons seen primarily during the day? Why are gibbous and full moons seen primarily at night? - Crescent moons are seen primarily during the day because they occur when the Moon is positioned relatively close to the Sun in the sky. During the waxing crescent phase, the Moon is following the Sun across the sky, meaning it is visible shortly after sunrise and before sunset. Similarly, during the waning crescent, it appears before the Sun rises. - Gibbous and full moons are seen primarily at night because they occur when the Moon is farther from the Sun in its orbit. During the full moon, the Moon is directly opposite the Sun, rising as the Sun sets and staying visible throughout the night. Gibbous moons (waxing or waning) are also visible mostly at night as they are closer to being opposite the Sun in the sky f. On the diagram below, you should be able to determine the moon’s phases at each of the 4 positions of Earth (A, B, C, D) A = 1st Quarter B = New Moon C = 3rd Quarter D = Full moon g. In the diagram above, what is the Earth’s phase at positions A and C, as seen from an astronaut on the Moon? Describe how the Earth would appear to an astronaut on the Moon at positions B and D. A= 3rd Quarter B= Full earth C= 1st Quarter D= New Earth 4. Solar and Lunar Eclipses: a. Why did many ancient civilizations believe that eclipses are bad omens as well as unpredictable? Many ancient civilizations believed that eclipses were bad omens and unpredictable due to their dramatic and sudden appearance, which could evoke fear and confusion. Eclipses involve the Moon or Earth blocking the Sun’s light, creating a striking visual phenomenon that might have been interpreted as a sign of the gods' anger or as a forewarning of significant events, such as disasters or conflicts. The unpredictable nature of eclipses contributed to this belief, as the ancient peoples lacked the scientific understanding and astronomical records that we have today. They could not accurately predict when eclipses would occur, leading to feelings of helplessness in the face of such powerful celestial events. This uncertainty, combined with the eclipse's ominous appearance, reinforced the idea that eclipses were connected to supernatural forces or portents of misfortune​ b. What is the cause of a solar eclipse? What is the Moon's phase when this Happens? A solar eclipse occurs when the Moon passes directly between the Earth and the Sun, casting a shadow on the Earth. This alignment blocks the Sun’s light from reaching certain areas on Earth. The Moon is in the New Moon phase during a solar eclipse, as it is positioned between the Earth and the Sun c. Describe the appearance of a total solar eclipse and a partial solar eclipse. During a total solar eclipse, the Moon completely covers the Sun from the perspective of an observer on Earth. This results in the darkest part of the Moon's shadow, known as the umbra, falling on the Earth. In this phase, the day turns into a temporary twilight, and the Sun's corona (the outer atmosphere) becomes visible around the dark disk of the Moon. The surroundings may also experience a noticeable drop in temperature, and the bright stars and planets may become visible in the sky. In contrast, during a partial solar eclipse, only a portion of the Sun is obscured by the Moon. Observers in the penumbra, the lighter part of the shadow, see a part of the Sun blocked, creating a crescent shape. The Sun's light is still present, but it appears diminished, and the eclipse's effects are less dramatic than in a total solar eclipse Difference in appearance between a total solar eclipse and a partial solar eclipse is: Total solar eclipse: - Seen from the umbra (Darkest part of the shadow) - The moon fully covers the sun (Sun is totally obscured) - No light from the sun reaches the ground Partial solar eclipse: - Seen from the penumbra (lightest part of the shadow) - The moon partially blocks the sun (Sun is partially blocked) - Some sunlight is still visible d. 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 - If an observer sees a total solar eclipse, they are standing within the umbra, the darkest part of the Moon's shadow. This is where the Moon completely covers the Sun. - If an observer sees a partial solar eclipse, they are standing within the penumbra, the lighter part of the Moon's shadow. In this case, only a portion of the Sun is obscured by the Moon. - If you are standing outside both the umbra and the penumbra during a solar eclipse, the Sun will appear normal, without any obscuration from the Moon. Note: Your location on earth determines which of these three possibilities you’ll experience during a solar eclipse: nothing, partial, or total. e. What is the cause of a lunar eclipse? What is the Moon's phase when this happens? Describe the appearance of a total lunar eclipse, a partial lunar eclipse and a penumbral lunar eclipse. A lunar eclipse occurs when the Earth passes between the Sun and the Moon, causing the Earth’s shadow to fall on the Moon. This can only happen when the Moon is in the Full Moon phase, as it is positioned opposite the Sun. - Total Lunar Eclipse: In a total lunar eclipse, the Moon passes completely into the Earth’s umbra (the darkest part of its shadow). During this phase, the Moon can take on a reddish color due to the light from the Sun being filtered through the Earth’s atmosphere, a phenomenon often referred to as a "Blood Moon." - Partial Lunar Eclipse: In a partial lunar eclipse, only a portion of the Moon enters the Earth’s umbra. As a result, part of the Moon will be darkened, while the remaining part stays illuminated by sunlight. - Penumbral Lunar Eclipse: In a penumbral lunar eclipse, the Moon passes through the Earth’s penumbra (the lighter part of its shadow). This type of eclipse is subtle and can be hard to observe, as the shading is very slight, causing only a small portion of the Moon to appear dimmer than usual​.  Appearance: During a lunar eclipse, an observer on the moon would see the sun disappearing, then completely blocked by the sun Visibility: Lunar eclipses are easier to see than solar eclipses because a larger geographic area of the earth is in the viewing area. To view a lunar eclipse you have to be on the night side of the earth and be able to see the moon. f. If a total lunar eclipse is seen, what is the Moon passing through? How about if a partial lunar eclipse is seen? How about if a penumbral lunar eclipse is seen? - If a total lunar eclipse is seen, the Moon is passing completely through the Earth’s umbra, the darkest part of its shadow. - If a partial lunar eclipse is seen, the Moon is only passing through a portion of the Earth’s umbra, meaning that only part of the Moon is darkened. - In the case of a penumbral lunar eclipse, the Moon is passing through the Earth’s penumbra, which is the lighter part of the shadow. This results in a subtle shading of the Moon, making it difficult to observe g. 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? If an observer on the night side of Earth witnesses a total lunar eclipse, not all observers on the night side will see a total lunar eclipse at the same time. This is because the visibility of the lunar eclipse can vary depending on the specific location of each observer. For example, those farther from the path of the Moon’s shadow might only see a partial eclipse or none at all. Additionally, geographical factors and local weather conditions can affect visibility, meaning that while some may witness the total lunar eclipse, others may not be able to see it simultaneously​. h. What are the criteria for a lunar eclipse and a solar eclipse?: Lunar eclipse: Moon must be full The earth must be in an eclipse season The observer must be on the earth’s night side Solar eclipse: The moon must be new The earth must be in a eclipse season The observer must be in the sun’s shadow (Umbra or penumbra) 5. The Eclipse Cycle and the Mayan Eclipse Records: a. Why don’t eclipses occur every New and Full moon? Eclipses don't occur every New and Full Moon because the orbits of the Earth, Moon, and Sun are not perfectly aligned. Specifically, the Moon’s orbit is tilted by about 5 degrees relative to Earth's orbit around the Sun (the ecliptic). This small tilt means that during most New and Full Moons, the Sun, Earth, and Moon are not in perfect alignment to cause an eclipse. For an eclipse to occur, the Moon must be in the right position during what is called an eclipse season. Eclipse seasons happen only twice a year, lasting about 31 to 38 days. During these periods, the Moon's orbit crosses the ecliptic plane, creating the potential for eclipses. If a New Moon occurs during an eclipse season, a solar eclipse may happen. If a Full Moon occurs, a lunar eclipse may take place​ b. What do we call the time period when eclipses can occur? On average, how many lunations 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? The time period when eclipses can occur is called an eclipse season. These seasons occur because the Moon’s orbit aligns with the Earth-Sun plane (the ecliptic), making it possible for the Sun, Earth, and Moon to align perfectly, resulting in eclipses​. - They happen twice a year, lasting 31-38 days each - There’s approximately 6 months between each eclipse season - During these periods, the moon’s orbit around the sun are coplanar, allowing for potential eclipses. Coplanar: When the two orbits make everything line up Number of Lunations Between Eclipse Seasons: On average, there are 5 = 177 days or 6 = 148 days lunations between eclipse seasons. A lunation is the time it takes for the Moon to complete one full cycle of phases, approximately 29.5 days. This means that an eclipse season recurs every 5 to 6 lunar cycles, depending on the starting position of the Moon in its orbit​. Why There Are Always at Least 1 or 2 Solar and Lunar Eclipses per Season: Each eclipse season typically yields at least one solar eclipse and one lunar eclipse. This is because: - A lunation (29.5 days) fits within the eclipse season (31-38 days) - When you enter a eclipse season, you’re guaranteed at least one eclipse - Each eclipse season typically yields 1-2 lunar eclipses and results in a minimum of 4 eclipses happening every year. - Solar eclipses occur during the New Moon phase when the Moon is positioned between the Earth and the Sun. - Lunar eclipses occur during the Full Moon phase when the Earth is between the Sun and the Moon. Since each eclipse season lasts about 31 to 38 days, there is usually enough time for both a New Moon and a Full Moon to occur. This ensures that at least one of each type of eclipse takes place. Occasionally, two solar or two lunar eclipses may happen in a single eclipse season if the timing aligns closely enough with the start and end of the season c. Why are lunar eclipses seen more frequently than solar eclipses? Lunar eclipses are seen more frequently than solar eclipses by individual observers for several key reasons: 1. Visibility from Half the Earth (Larger viewing area) - It is easier to see as a lunar eclipse because a larger geographic area of the earth is in the viewing area. For a lunar eclipse you just need to be on the night side of the earth and be able to see the moon. - In contrast, solar eclipses are visible only along a narrow path of totality on Earth. Observers outside this path may only see a partial eclipse or miss it entirely. 2. Duration and Frequency of Visibility - Lunar eclipses tend to last longer than solar eclipses. A total lunar eclipse can last for several hours, providing more opportunity for people to see it. - Solar eclipses are brief, with totality lasting just a few minutes at any given location. 3. Location Constraints - To see a solar eclipse, you need to be in the small area where the Moon’s shadow (umbra or penumbra) touches the Earth’s surface. The same solar eclipse might not be visible to other parts of the world. - Lunar eclipses, however, can be seen from a wide range of locations on Earth's night side, regardless of where the observer is positioned​. You don't have to be in a geographically significant location. You can observe a lunar eclipse from anywhere of the night side of the earth where the moon is visible. On average a person will see one solar eclipse every 5 years (total or partial) A lunar eclipse is seen approximately every 2 years d. On the diagram in question 3, you should be able to identify the position(s) (A, B, C and/or D) at which either a solar eclipse or lunar eclipse is possible Key Concepts of Eclipses: - Solar Eclipse: Occurs when the Moon is between the Earth and the Sun, casting a shadow on Earth. This only happens during a New Moon phase. Position in the Diagram: This occurs near Position B (New Moon). - Lunar Eclipse: Occurs when the Earth is between the Sun and the Moon, casting a shadow on the Moon. This only happens during a Full Moon phase.  Position in the Diagram: This occurs near Position D (Full Moon). Identifying Eclipse Positions from the Diagram: Position B (New Moon): Solar Eclipse Possible: The Moon aligns between the Earth and the Sun. If the alignment is perfect, a solar eclipse can occur. Position D (Full Moon): Lunar Eclipse Possible: The Earth aligns between the Sun and the Moon. If the alignment is exact, the Earth’s shadow covers the Moon, resulting in a lunar eclipse. Summary: Solar Eclipse Possible: Position B (New Moon) Lunar Eclipse Possible: Position D (Full Moon) e. 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 could occur. The Dresden Codex, an ancient Mayan manuscript, provides compelling evidence that the Maya had a profound understanding of the eclipse cycle and could predict eclipse dates with remarkable precision. It contains over 400 months (34 years) worth of eclipse predictions. Some pages contain 'eclipse warning tables' predicting eclipses over a period of 12,000 years. Here are the key pieces of evidence from the codex that demonstrate their knowledge: 1. Tracking the Eclipse Cycle with Lunations After observing eclipses for hundreds of years, they deciphered a repeating pattern and recorded it on pages 51-58 of the Dresden Codex The codex shows that the Maya tracked time between eclipse seasons using a system of lunations. They identified two key numbers: 177 days (approximately 6 lunations) 148 days (approximately 5 lunations) These numbers reflect the time intervals between consecutive eclipse seasons. The Maya observed that the interval could shift between 5 and 6 lunations, depending on the Moon's position at the start of the cycle​. 2. Long-Term Observations Recorded The codex demonstrates that the Maya collected data over hundreds of years. They identified repeating patterns in the Sun-Moon alignments that allowed them to predict when future eclipses would occur. At day 11,960 (18 years) of eclipse predictions, they realized that the 3 Tzolk'in dates repeat on the same days. This represented one of the most successful long term observing campaigns that led to true understanding of the cycle of the sky. 3. Prediction of Eclipses with Three-Day Accuracy The Dresden Codex contains columns of numbers and dates that correspond to eclipse predictions. These records pinpointed specific three-day windows within an eclipse season during which an eclipse was expected. If no eclipse occurred, the Maya believed it was due to their geographic location rather than a failure in prediction. 4. Eternal Prediction of Eclipses through Repetition The Maya discovered that the Tzolk’in calendar dates (part of their 260-day cycle) would align with eclipse seasons every 18 years (the Saros cycle). They understood that the same eclipse pattern would repeat infinitely over time, enabling them to forecast eclipses for eternity by following these cycles. 5. Religious and Symbolic Context of Eclipses In addition to scientific observations, the codex links eclipses to religious rituals and the behavior of gods, such as the Sun and Moon gods fighting. The Maya would conduct ceremonies to appease these gods during predicted eclipse periods, further indicating their confidence in the accuracy of their predictions. The Dresden Codex reflects the Mayan civilization’s sophisticated understanding of the eclipse cycle. Their meticulous recording of lunations, ability to identify repeating cycles, and three-day prediction windows demonstrate a system of knowledge that allowed them to forecast eclipses indefinitely. f. Why did the Maya believe that they had occasionally prevented an eclipse by worshiping the Sun and Moon god? The Maya believed that their rituals and ceremonies could prevent eclipses because they interpreted these celestial events as **conflicts between the Sun and Moon gods**. According to their worldview, an eclipse: symbolized a dangerous struggle or fight between these gods, which could result in disaster if not addressed properly through religious practices. Belief in Divine Intervention through Rituals: - The Maya performed **ceremonies and rituals** during the predicted three-day windows of potential eclipses, aiming to appease the Sun and Moon gods. - If no eclipse occurred during the expected time frame, the Maya interpreted this as **success in their rituals**, believing that their worship had prevented the celestial conflict from taking place. Geographic Limitation Misunderstood as Divine Influence: - The Mayans’ prediction system was highly accurate in identifying when an eclipse could occur, but eclipses are only visible from specific locations on Earth. If the eclipse occurred elsewhere and was not visible to them, the Maya would assume that their rituals had worked and averted the event. This belief in the effectiveness of their rituals reinforced the importance of conducting religious ceremonies at the right times, ensuring that the gods remained appeased to avoid cosmic disasters such as eclipses. 6. The Cycle of Planet Venus and the Mayan Venus Records: a. What 2 characteristics of the planet Venus caused the Mayans to identify it as a special kind of star? The Maya identified Venus as a special kind of star due to the following two key characteristics: 1. Exceptional Brightness: - Venus is the third-brightest object in the sky after the Sun and the Moon, making it highly noticeable. Its brilliance and steady glow, particularly during certain parts of its orbit, caught the attention of the Maya and led them to treat it as a significant celestial body tied to mythology and rituals. 2. Regular and Predictable Movements: - Venus follows a predictable cycle, appearing alternately as the morning star (before sunrise) and evening star (after sunset). This cycle, known as the synodic period of Venus, lasts approximately 584 days. The Maya meticulously tracked these movements and incorporated them into their calendar systems, treating Venus’s appearances as symbols of important events, such as warfare or religious ceremonies. c. 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? After Its Bright Heliacal Rise (~8 months): - Seen as:Morning star (visible just before sunrise in the eastern sky). - visible for 8 months - gets dimmer each day as it moves away from earth - Brightness: It gradually dims over this period because Venus moves farther away from Earth in its orbit, increasing the distance between the two planets. Why Does Venus Disappear? - After about 8 months, Venus reaches a point called superior conjunction, where it moves behind the Sun from Earth's perspective. During this phase, Venus is obscured by the Sun's light and becomes invisible for about 3 months. When Venus Reappears - Seen as:Evening star (visible just after sunset in the western sky). - visible for about 8 months - Brightness: Venus initially appears dim but gets brighter over the next 8 months as it approaches Earth in its orbit and reflects more sunlight. (Gets brighter each day as it approached earth) Second Disappearance Before the Next Heliacal Rise - Venus disappears again when it reaches an inferior conjunction—the point where it passes between the Earth and the Sun. During this phase, Venus is too close to the Sun to be visible. This marks the transition to its next heliacal rise when it re-emerges as a morning star. This 584-day synodic cycle of Venus—alternating between bright appearances as the morning and evening star, followed by periods of invisibility—made it an essential part of Mayan astronomical observations and rituals. Key points in the cycle: - Inferior Conjunction: Venus is between earth and sun, not visible - Superior conjunction: Venus is hidden behind the sun for about 3 months - Heliacal rise: first day venus becomes visible after conjunction - Maximum brightness: Occurs about a week before inferior conjunction d. Look up the date of the most recent heliacal rise of Venus, and use this to figure out Venus' current appearance. Is it visible or invisible? If it's visible, is it a morning or evening star? Is it getting brighter or dimmer? If it's invisible, why is This? Currently, Venus is visible in the evening sky as an evening star. After its superior conjunction in June 2024, when it passed behind the Sun, Venus re-emerged in July 2024 and will remain visible in the west after sunset through early 2025. It is now slowly ascending higher above the horizon each evening, becoming more prominent. Venus is getting brighter as it approaches Earth in its orbit, reflecting more sunlight toward us. Its brightness will peak near the end of February 2025, just before it begins to move closer to the Sun in our sky. Venus will continue in this role until March 23, 2025, when it reaches inferior conjunction, passing between Earth and the Sun, and becoming temporarily invisible due to the Sun's glare. After that, Venus will reappear as a morning star in late spring 2025, visible just before sunrise, marking the next phase of its synodic cycle. e. Describe the evidence in the Mayan Dresden codex that tells us that the Maya understood the Venus cycle and were able to predict, for eternity, the dates on which the appearances and disappearances of Venus would occur. The Dresden Codex, an ancient Mayan manuscript, contains detailed records demonstrating that the Maya had a profound understanding of the Venus cycle and could accurately predict the planet’s appearances and disappearances. This knowledge was embedded in their astronomical and calendrical systems, providing a basis for predictions that extended indefinitely into the future. Here's the key evidence: 1. 584-Day Synodic Venus Cycle - The Maya tracked the synodic period of Venus, which lasts approximately 584 days—the time it takes for Venus to complete one full cycle of its appearances as a morning and evening star. The codex records this cycle with incredible precision, showing the points where Venus would rise heliacally (first visible appearance) and set invisibly behind the Sun during conjunctions. 2. Mathematical Integration into Calendars - The Venus cycle was integrated into the Mayan Long Count calendar and the Tzolk’in ritual calendar. Every 104 years (or 65 Venus cycles), the same Venus events would align precisely with the calendar, demonstrating that the Maya recognized this repeating pattern. This allowed them to predict Venus's behavior across generations and for eternity. 3. Tracking Morning and Evening Star Transitions - The codex shows that the Maya carefully observed the shifts between Venus’s roles as the morning star and evening star. They noted the specific days of disappearance (during inferior and superior conjunctions) and reappearances, ensuring accurate forecasting of these celestial events for future rituals and agricultural activities. 4. Symbolic and Ritual Importance of Venus’s Movements - Venus was not only tracked for scientific purposes but was deeply embedded in Mayan mythology and religious practices. Its bright reappearance in the sky often symbolized significant events, such as the start of wars or important ceremonies. The predictions recorded in the codex provided precise windows for these events, giving the Maya confidence in the alignment of their celestial and ritual calendars. 7. Babylonian Astronomy: a. According to historians, what was it about climate conditions in the region of Ancient Babylon that motivated the Babylonians to study the sky? Historians suggest that the Babylonians' motivation to study the sky was driven by climate instability and unpredictable weather patterns in their region. In ancient Mesopotamia, reliable weather conditions were essential for agriculture, especially given the region’s reliance on seasonal rains and the flooding of rivers like the Tigris and Euphrates. However, irregular rainfall and droughts often disrupted planting cycles and food production​. This uncertainty pushed the Babylonians to develop long-term sky-watching practices. They believed that celestial events, such as the movements of stars and planets, could be used to predict future events on Earth, including agricultural seasons and weather changes. By closely observing celestial patterns, they hoped to anticipate changes that could impact harvests and water availability. Their efforts to correlate astronomical phenomena with earthly events reflect the early connection between astronomy and astrology, as they sought both scientific predictions and divine guidance through the stars to mitigate the risks posed by their environment b. Why are there so many ‘60s’ in our units for time and angle? The prevalence of the number 60 in our units for time and angle measurement can be traced back to ancient civilizations, particularly the Babylonians. Here's why it's so common: 1. Ancient Babylonian system: The Babylonians developed a base-60 numbering system]. 2. Advantages of base-60: - It allows for easy handling of fractions without dealing with decimals - The system was quick to write and easy to understand, using pictographs 3. Astronomical observations: This system facilitated long-term astronomical observations, as it provided a language and numbering system that was easily applicable. 4. Legacy: Our modern use of the base-60 system for time and degrees is inherited from this ancient system. The effectiveness and practicality of this system have led to its continued use in measuring time and angles today. 8. The Naming of the Visible Planets: a. For each of the 5 visible planets, what aspect of their appearance was used to choose the Babylonian/Greek god to name them for? The appearance of planets influenced their naming after Babylonian and Greek gods in several ways: Mercury: Named after messenger gods due to its quick movement in the sky - Babylonian: Nabu (god of wisdom and writing) - Greek: Hermes (messenger god) - Roman: Mercury (messenger god) Venus: Named after love goddesses due to its brightness - Babylonian: Ishtar - Greek: Aphrodite - Roman: Venus (goddess of love) Mars: Associated with war gods due to its red color - Babylonian: Nergal (god of war) - Greek: Ares  - Roman: Mars (god of war) Jupiter: Named after king gods - Babylonian: Marduk - Greek: Zeus - Roman: Jupiter (king of the gods) Saturn: Associated with harvest/old age - Greek: Kronos - Roman: Saturn (god of harvest/old age) - Babylonian: Ninurta, farmer god. The Babylonians originally named these visible planets after their gods, and the names were later adapted by Greek and Roman cultures 9. Daily Cycle of the Stars: a. Why do the stars move across the sky throughout the night? The stars appear to move across the sky throughout the night due to the Earth's rotation. Here's why: - Earth's Rotation: The Earth is constantly spinning on its axis, which creates the illusion that the stars are moving. - Celestial Sphere Concept: We can imagine all celestial objects pasted on the inside of a giant sphere rotating around us, creating the day-night motion. - Star Trails: As the Earth spins, stars appear to trace pathways in the sky, resulting in what we call star trails. - Celestial Poles: Stars seem to rotate around the North Celestial Pole (in the Northern Hemisphere) or the South Celestial Pole (in the Southern Hemisphere). - Stationary Stars: Some stars near the celestial poles never rise or set, appearing to circle the pole continuously. This apparent motion of stars is actually a reflection of our planet's rotation, even though we don't feel like we're spinning. b. 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? When standing on Earth's North Pole, the center of rotation for the stars is the North Celestial Pole, which is directly overhead. This point is closely aligned with Polaris, also known as the North Star. As we move from the North Pole towards the equator: 1. The North Celestial Pole appears to move lower in the sky. 2. There's a direct relationship between your latitude and the height of the celestial pole in the sky. 3. At the equator, both the North and South Celestial Poles would be visible on the horizon. This change in the position of the celestial pole is due to Earth's curvature and our changing perspective as we move across different latitudes. c. 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? - When standing on the equator and facing north, the stars will appear to rotate around the North Celestial Pole. The North Star (Polaris) will be near the center of this rotation. From the equator, both celestial poles (north and south) are visible at the horizon, so the stars rise in the east and set in the west in a smooth arc across the sky. - When facing south at the equator, the stars will appear to rotate around the South Celestial Pole, which is located on the horizon as well. As you move south of the equator, the South Celestial Pole rises higher in the sky, and at the South Pole, it would be directly overhead d. What objects (if any) mark the North and South Celestial Poles? - North celestial pole is marked by polaris (the north star) - The south celestial pole is marked by nearby objects/constellations. The large and small magellanic clouds (dwarf galaxies orbiting our galaxy) form a triangle with the south celestial pole. e. In the Northern hemisphere, how can we use a star to determine our latitude on Earth? In the Northern Hemisphere, you can use Polaris (the North Star) to determine your latitude. The altitude of Polaris (its angle above the horizon) is approximately equal to your latitude. For example, if Polaris is 40 degrees above the horizon, you are at a latitude of about 40 degrees north. The relationship between the altitude of Polaris and latitude is direct and provides a simple way to navigate and locate your position 10. Annual Cycle of the Stars: a. Why do we see different stars and constellations at different times of the year? We see different stars and constellations at various times of the year because of Earth's annual orbit around the Sun. As Earth moves, the nighttime side of the planet faces different parts of the celestial sphere, revealing different stars and constellations. Essentially, during different seasons, we are looking at different sections of space, which changes the constellations that are visible in the night sky. This is why some constellations are associated with specific times of the year, such as Orion being visible in the winter​ b. How is it possible to use a star to determine when 1 year has elapsed? It is possible to use a star to determine when one year has elapsed by observing its heliacal rise. The heliacal rise occurs when a star, after being hidden by the Sun for a period, becomes visible again just before sunrise. This marks a specific moment in the Earth's orbit around the Sun. By tracking the position of a star, such as Sirius, and noting when it returns to the same position in the sky (for example, at its heliacal rise), you can measure the passage of one year, which corresponds to one complete orbit of the Earth around the Sun 11. Astronomy in Ancient Egypt: a. What was the primary motivation for studying the sky in Ancient Egypt? The primary motivation for studying the sky in Ancient Egypt was to predict the annual flooding of the Nile River, which was crucial for agriculture and survival. The Egyptians observed the heliacal rise of Sirius, the brightest star in the sky, which coincided with the flooding of the Nile. This predictable event helped them develop a calendar to time agricultural activities and plan for the floods, ensuring the prosperity of their civilization b. Why was the star Sirius used to mark the beginning of a new year? The star Sirius was used to mark the beginning of a new year in Ancient Egypt because its heliacal rise—the first time it became visible in the pre-dawn sky after being hidden by the Sun—coincided with the annual flooding of the Nile River. This flooding was a critical event for Egyptian agriculture, as it provided the water and fertile soil necessary for crops. The reappearance of Sirius served as a reliable natural signal, helping Egyptians track the yearly cycle and mark the start of their new year c. Why did the Ancient Egyptians divide the day into 24 hours? The Ancient Egyptians divided the day into 24 hours as part of their system for tracking time, which was closely tied to their observations of the sky. They based their division of time on the movement of the stars. Specifically, they used 12 stars or star groups, known as decans, that rose consecutively during the night. Each decan represented a segment of time, and the night was divided into 12 hours. They mirrored this by dividing the daylight hours into another 12 segments, making a total of 24 hours for a full day. This system became the foundation for the 24-hour day we use today​ 12. Origin of the Modern Calendar: a. 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? We add a leap day every four years to account for the fact that a solar year (the time it takes for Earth to complete one orbit around the Sun) is not exactly 365 days, but about 365.24 days. Without this adjustment, our calendar would gradually fall out of sync with the seasons over time. By adding an extra day every four years, we correct this slight difference. This rule was incorporated into our calendar by Julius Caesar when he introduced the Julian calendar in 45 BCE. He learned this rule from the astronomer Sosigenes of Alexandria, who was part of the Egyptian court of Cleopatra. The Egyptians already had a well-developed understanding of the calendar, and Sosigenes advised Caesar on the leap day adjustment to keep the civic calendar aligned with the solar year b. Why do we now use the Gregorian calendar instead of the Julian calendar? We use the Gregorian calendar instead of the Julian calendar because the Julian system, while effective, was not perfectly accurate. The Julian calendar assumed a year was 365.25 days, but a solar year is actually about 365.2425 days. This small difference of 11 minutes per year caused the calendar to drift out of alignment with the seasons over centuries. By the 16th century, this drift had accumulated to about 10 days, which was particularly problematic for determining the date of Easter. To fix this, Pope Gregory XIII introduced the Gregorian calendar in 1582. The Gregorian reform made two key changes: Adjusting the leap year rule: Years divisible by 100 are not leap years unless they are also divisible by 400 (e.g., 1600 and 2000 were leap years, but 1700, 1800, and 1900 were not). Realigning the calendar with the equinox by skipping 10 days, ensuring the dates would match the seasons more closely going forward. This calendar was more accurate over the long term, and it is the one we use today​ 13. The Zodiac: a. Where are the zodiac constellations? Why were they significant to the Babylonian astrologers? The zodiac constellations lie along the ecliptic, the path the Sun, Moon, and planets appear to follow across the sky throughout the year​. These constellations were important to Babylonian astrologers because they tracked the movements of celestial bodies believed to be associated with divine figures. By mapping the pathway of these gods (such as the Sun and planets), Babylonians thought they could predict future events and influence their lives. The Sun's path was especially significant, as it symbolized the changing seasons and cycles of life b. Why can we not see our astrological constellation in the month we were born? The reason is due to the precession of the equinoxes, a slow shift in Earth's rotational axis that causes the constellations to move gradually over time. Thousands of years ago, the zodiac signs aligned with the constellations visible during specific months. However, the precession has shifted the positions of these constellations by about one month from where they were when the zodiac system was first created​. For instance, people born under Taurus now find the Taurus constellation appearing in June, not during their birth month. c. Why have our zodiac signs changed since their original definitions by the Ancient Greeks? Our zodiac signs have changed over time due to the procession of the equinoxes. This astronomical phenomenon takes approximately 26,000 years to complete a full cycle and causes the positions of the constellations to drift over time. The zodiac signs we use today are based on the positions of the Sun in those constellations 2,000 years ago. As a result, the constellations no longer match the astrological signs assigned to them during ancient Greek times, leading to the discrepancy between traditional zodiac dates and the actual constellations in the sky today