Project Fulcrum is supported by the National Science Foundation and the University of Nebraska, in partnership with Lincoln Public Schools

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1 A Guide to Space Project Fulcrum is supported by the National Science Foundation and the University of Nebraska, in partnership with Lincoln Public Schools Version 1.0 1/26/06 Project Fulcrum 1

2 1. Introduction 1.1. How to Use These Materials Philosophy. Project Fulcrum is based on the strategy shown in Figure The first aspect of planning a lesson is deciding what it is you want your students to know and/or be able to do. The second step is to determine what criteria you (or the CRTs) will use to evaluate whether they have learned the items you picked in the first step. The final step is to pick those activities, materials, etc. that will accomplish your goal and facilitate your evaluation of your students. Don t get in the habit of picking the activity first. Activities should serve your goals for your students, not vice-versa. What do you want students to know and be able to do? How will you know that they have learned what you wanted them to learn? What materials, activities, discussions, etc. will help them learn what you want them to learn? Figure 1.1: Lesson design philosophy Background Material. The background material in this section includes information on the basic concepts required to understand space, plus some additional materials on nature of science, technology and history Objectives. Each LPS objective is stated, and then the fundamental concepts that are necessary to master the objectives are discussed, with references to the appropriate background sections Key Concepts. Each objective has multiple smaller ideas, all of which are necessary to understand if students are to meet the objectives. These are presented as bullets, with the goal being to be as specific as possible Activities. The activities are not presented in a specific order. You should choose activities via the goals they address. You may plan different activities for different sets of students, depending on their needs and their sophistication. Do not assume that the order in which they are presented here necessarily is the order in which you should utilize them Work in Progress. This is a work in progress and is only a draft at this point. We welcome your input, ideas and other contributions Opportunities to Work with a Project Fulcrum Scientist Project Fulcrum scientists are graduate students pursuing advanced degrees in math, science or engineering. They will plan with you to identify hands-on activities and other resources that can help your students master the LPS objectives for the particular unit. Project Fulcrum scientists are not teachers: they are there to partner with you and help you achieve the goals you have for your students. Working with a Project Fulcrum scientist has many benefits An opportunity for your students to make contact with a working scientist and broaden their image of science and scientists; Content expertise, including innovative ways to demonstrate and experiment with concepts that sometimes are difficult to teach; Increased opportunities to use hands-on, inquiry-based experiences to help your students learn. Version 1.0 1/26/06 Project Fulcrum 2

3 One Lead Teacher is required for each school. Preference will be given to schools that have teachers interested in working with the Lead Teacher on the same unit. Lead Teachers from different schools will meet to share ideas and resources, forming a community of practice based around a specific content unit. The Lead Teacher has the following responsibilities: Attend a three-hour hands-on content workshop prior to the start of the unit. Attend a two-hour Project Fulcrum orientation meeting to learn how Project Fulcrum works Attend a two-hour planning meeting prior to starting the unit Complete a weekly journal during the time you are working on the unit Attend a two-hour meeting at the midpoint of the unit Attend a two-hour end-of-unit meeting Participate in pre- and post-surveys Write a final reflective essay on how the experience has affected the way you teach science Communicate with other teachers at the school who are participating. Lead teachers will be paid at the rate of $18/hr (with one hour allotted for each journal). All payments are made at the end of the quarter in which the unit is taught. 2. Objectives 2.1. Objective The student will be able to name and describe the parts of the solar system Key Concepts The Solar System is a grouping of nine known planets that orbit the Sun. The Sun is a star, just like the stars in the night sky Vocabulary Earth is the planet we live on and is the third planet from the Sun. The Earth is the only known planet that has an atmosphere that can support human life. Jupiter is the fifth planet from the Sun and the largest planet in the solar system. One thousand Earths could fit inside Jupiter if it was hollow. Jupiter has more mass than all of the other planets combined. Mars is the fourth planet from the Sun and is commonly called the red planet because of its red rocks, soil, and sky. The red color is due to the presence of iron oxide (aka: rust). Mars is the third smallest planet and is thought to be the best candidate for harboring life of any type. Mercury is the closest planet to the Sun and is the second smallest. The surface of Mercury is a lot like the Moon: It has has many craters from meteor impacts. Neptune is the eighth planet from the Sun and the fourth largest. Neptune looks blue due to the large amount of methane in the atmosphere. If Neptune were hollow, 60 Earths would fit inside of it. A Planet is body in space that doesn t give off light and only reflects light from stars. There are nine commonly accepted planets in our solar system that revolve around the Sun. Pluto is the furthest planet from the Sun on average and the smallest by far. Pluto is made up of mostly rock. A mission to Pluto called New Horizons was just launched in January 2006 and will reach Pluto in Pluto is the only one of the nine known planets we have not sent a space mission to explore. Version 1.0 1/26/06 Project Fulcrum 3

4 Saturn is the sixth planet from the Sun and is the second largest. Saturn is known for its rings, which are made up mostly of ice and a small amount of rock. The Solar System includes the Sun and nine known planets orbiting around the Sun. The Solar System also includes asteroid belts and comets. A Star is a body in space made up of gases at very, very high temperatures that provides its own illumination (in contrast to planets, which reflect light). Our Sun is an example of a star. The Sun is the star about which the nine known planets of our solar system orbit. It is the major source of the light and warmth for Earth. Uranus is the seventh planet in the solar system and is the third largest. Like Neptune, Uranus appears blue due to the methane in its atmosphere. Uranus has rings like those of Saturn, but the rings are not as pronounced. Venus is the second planet from the Sun, sixth largest, and is very close to the size of Earth. Venus is the most-visited planet by unmanned spacecraft from Earth. Scientists believe that Venus was once very much like Earth, but that the extreme heat from the Sun would have boiled away any water on the surface. Pictures (From the closest to furthest from the Sun, photos courtesy of NASA) The Sun as seen from the Skylab Space Station Mercury from Mariner 10 spacecraft Venus from Galileo spacecraft Earth showing Africa from space Version 1.0 1/26/06 Project Fulcrum 4

5 Mars from Viking Orbiter Jupiter from Hubble Space Telescope Saturn from Voyager II Uranus from Voyager II Neptune from Voyager II Pluto and its moon Charon from Hubble Space Telescope Version 1.0 1/26/06 Project Fulcrum 5

6 Figure 2.1: The orbits and positions of the planets. In order to fit them on one piece of paper, they are not drawn to scale. All the planets except Pluto orbit in the same plane. Pluto s orbit is canted with respect to the other planets Some Controversy: Is Pluto a Planet and Is There a Tenth Planet? You may have read in the newspapers that there are debates about whether Pluto is a planet and whether there are actually only nine planets. Right now, the solar system includes nine known planets (described above); however, this definition is in flux. Part of the problem is that astronomers don t really have an agreed-upon definition for what makes a planet a planet. In 2000, the Rose Center for Earth and Science at New York City's American Museum of Natural History (one of the most prestigious planetariums in the country) left Pluto out of its planet exhibit. Why? Many astronomers argue that Pluto should never have been classified as a planet. It is very small, its orbit is not in the same plane as the other planets orbits, and we are discovering that there are lots of objects of comparable size in the same region. Pluto occupies a part of the solar system called the Kuiper belt (Ky -per belt). The Kuiper Belt is a region in our outer solar system that contains many comets that have orbits of less than 200 years. The Kuiper belt lies beyond Neptune's orbit and may contain as many as 100 million Kuiper-belt comets. Objects in this belt are commonly referred to as Kuiper belt objects. Not the most glamorous name, but descriptive. In 1999 the International Astronomical Union (IAU), which is a professional society of astronomers, decided against making Pluto a minor planet or listing it as both a planet and a member of the Kuiper belt. The story gets even more complicated, however. In 2005, Scientists at Palomar Observatory (outside San Diego, CA), announced that they had discovered what they claim is a tenth planet, which they proposed calling Xena. Planet Xena has one moon, which the team is calling Gabrielle. Planet Xena, whose official name is 2003 UB313, is now at its aphelion the furthest distance from the Sun which is about 9 billion miles away from the Sun. This makes it about 100 times more distant than the Earth, and about three times more remote than Pluto. UB313 has a highly elliptical orbit that is inclined about 45 degrees from the main plane of our Solar Version 1.0 1/26/06 Project Fulcrum 6

7 System. (Pluto s orbital plane also is different than the other planets orbital planes.) The distance of closest approach will be about 3.5 billion miles and the orbital period is 557-years. For comparison, Pluto s mean distance from the Sun is about 3.6 billion miles and it orbits in just years. Most importantly, Xena is thought to be about one-and-a-half times larger than Pluto. If Pluto is a planet, surely Xena is a planet; however, there are a number of astronomers arguing that Pluto be dropped from the official list of planets. The controversy is not settled keep an eye on the newspaper for more information. This is a potentially good place to communicate to your students that science isn t done we constantly are learning new things and revising our models of objects like the solar system Activities Remembering the Order of the Planets: Have the entire class help create a mnemonic device for the initials of the planets from Mercury to Pluto, m.v.e.m.j.s.u.n.p. For example, Many Very Excited Martians Jump Super Umbrellas Near Pluto or My Very Eager Mother Just Sewed Us New Pajamas Resources General Information: (has an Educators and a Students section) Pluto and Xena b11a4dc&ei=5070 is a New York Times article about Pluto being or not being a planet has a table that lets students compare the characteristics of other planets with Pluto and decide for themselves whether Pluto is a planet or not. has a news story about planet Xena Objective The student will be able to describe the motion of objects in the sky such as sun, moon, and planets Key Concepts Planets move around the sun in a path called an ellipse. The motion of the planets is determined by gravitational interactions. The strongest interaction is between the Sun and the planets; however, planets also exert gravitational attraction to each other. Satellites stay in orbit about their planets because of the gravitational attraction of the planet. A constellation is a grouping of distant stars Vocabulary A Constellation is a formation of stars seen as a figure or design in the night sky; such as the Big Dipper (Ursa Major) or Little Dipper (Ursa Minor). For more information and a constellation list, the Hawaiian Astronomical Society has a helpful site at in the Deepsky Atlas section. Version 1.0 1/26/06 Project Fulcrum 7

8 An Ellipse is an oval-like shape that describes the path of the planets in the solar system as they travel around the Sun. Taurus Gravity is the force of attraction between Gemini Aries Cancer Pisces bodies in space and other objects. Planets with larger masses have a larger attractive force and the gravitational force gets Earth Leo Aquarius stronger as objects get closer to each other. The Moon is a small planet that revolves Sun around the Earth and reflects the light of Virgo Capricorn Libra Sagittarius Scorpio the Sun during the night. Neil Armstrong became the first person to step on the Moon on July 20 th, An Orbit is the path a body in space takes as it travels around another body in space. The Earth is in orbit around the Sun, and the Moon orbits the Earth. A Satellite is any body in space that orbits another body. The Moon is a satellite of the Earth. Satellite also refers to any object launched to orbit Earth or another body in space The Stars The stars in the night sky appear to move from night to night relative to a reference on Earth like a tree or the top of your house. Stars rise in the east and set in the west, like the Sun and Moon. Although the stars move relative to the Earth, they do not appear to move relative to one another. Groups of star are called constellations. Although you can think of constellations rising and setting, stars in different parts of the sky move at different rates (relative to the Earth they don t move relative to each other). Each hemisphere has one point that doesn t move. If there are no stars right at this point, the stars near the point move in a very small circle, moving once around the circle each day. The closer you are to a pole, the less motion you observe. The point in the Northern Hemisphere is approximately located by the North Star, Polaris. The circular motion can be observed by mounting a camera to take time-exposure pictures of the motion of these stars. (See for such a picture) Figure 2.2: Orion as seen from the Hubble Space Telescope. (The lines are drawn to help you see the constellation.) Version 1.0 1/26/06 Project Fulcrum 8

9 The Celestial Sphere. The Sun (along with the Moon and planets except for Pluto) moves across only a certain path in the sky. The stars are independent of the motions of the Sun and the planets and they maintain the same positions relative to each other. Because the stars do not appear to move relative to one another, it is convenient to picture them as being contained upon a giant sphere that surrounds the Earth. If you expanded the Earth until it reached the stars, the Earth s equator would be the celestial equator. Earth s North Pole would be the North Celestial Pole and Earth s South Pole would be the South Celestial Pole. If you stand in a flat area at night, you will see a one-half of the celestial sphere in the sky. You can think of the celestial sphere as the boundaries to the universe. The Babylonians used the stars to keep track of time and to navigate. They noticed that the sun moved only through a particular segment of the sky, called the ecliptic. They marked the ecliptic by using a set of stars that could be viewed as belonging to twelve constellations, most of which represented animals. The word zodiac means circle of animals and this band of twelve constellations is called the zodiac. The Sun appears to traverse the ecliptic once per year, spending approximately one month in each of the constellations of the zodiac. The ecliptic and the celestial equator intersect at two points, directly opposite one another. These points correspond to the equinoxes and when the Sun appears at these points, day and night are each about 12 hours long at all locations on Earth. 1 The Sun traces a path through the sky that is inclined by an angle of 23.5 degrees relative to the celestial equator. The Sun appears to move along the ecliptic at a rate of about 1 per day Planetary Motion Five planets can be observed with the naked eye: Mercury, Venus, Mars, Jupiter, and Saturn. Uranus, Neptune and Pluto are so far away that they require a telescope. Although planets look like stars in the night sky, they don t behave the same way as stars. Planets rise in the east and set in the west (like stars), but they drift a bit to the east relative to the stars. Stars move across the sky but maintain their positions relative to each other. The planets can have different positions relative to the fixed background of stars. This feature (along with the fact that star twinkle and planets don t) is what allows planets to be identified as distinct from stars. The Greek word planetes means wanderer, which arose from the unusual motions of the planets compared to the stars. ellipse foci b aphelion c a foci perihelion Figure 2.3: The quantities describing anfigure 2.4: The aphelion and perihelion ellipse: the semi-major axis, a, the semi-ominor axis, b, and the distance from one an elliptical orbit. foci to the origin, c. 1 See the applet at: Version 1.0 1/26/06 Project Fulcrum 9

10 Orbits. From the start of recorded history, people took note of where the planets were and how their positions changed each night. This enabled them to know that different planets travel at different speeds, because the time between Mercury appearing in the same position is much less than the time between Saturn appearing in the same position. The period is the time is takes a planet to make one complete circle around the Earth. Anatomy of an Ellipse If you place two points on a line and attach a string to each point, then draw a pencil line in all positions where the string is stretched fully, you get an ellipse. The sums of the distances from the foci to any point on the ellipse are constant. An ellipse has a semi-major axis (the longer of the two with the total length denoted by 2a) and a semi-minor axis (the shorter of the two). If c is the distance from the origin to either of the foci, the ratio c/a gives you the eccentricity, e. The quantities a and e completely define an ellipse. The smaller e is, the more circular the ellipse is. The Earth's orbit is very close to a circle, with e = Mars has an eccentricity of and Mercury has an eccentricity of Most other planets have an eccentricity comparable to the Earth s. Pluto has such a large eccentricity (0.248) that it actually becomes close to the Sun than Neptune during part of its orbit. The eccentricities of Earth and Mars are small enough that if you saw a scale drawing of an orbit on a sheet of paper, your eye would not be able to distinguish it from a circle. The orbit of Comet Halley, on the other hand, has e quite close to 1. Different positions along the orbit have been given names to make it easier to talk about them. The perihelion is the position when the planet closest to the Sun. The aphelion is the position when the planet is farthest from the Sun, as shown in Figure 2.4. (helios is Sun ). For satellites orbiting Earth (which also have an elliptical path), we speak of the perigee and the apogee. (geos is Earth in Latin.) Johannes Kepler found that the planets must move around the Sun with variable speed. A planet close to perihelion moves quickly; when it is close to aphelion, it moves more slowly. The area is proportional to the distance from the planet to the Sun and how far the planet travels in a particular time. Although the ellipse is a symmetric shape, the motion of the planet along the ellipse is not symmetric. One can make a loose analogy with a stone thrown upwards. It starts off with some speed, and slows as it rises. At the very top of its path, it comes to a stop and reverses direction. It them speeds up again. The motion of a planet about the Sun is similar Gravitational Interaction The reason the planets stay in orbit about the Sun, and the reason their paths are elliptical is because of the force of Gravity. All objects with mass have a gravitational attraction to each other. The gravitational attraction increases as the masses of the objects increase and also increases as the objects get closer to each other. The Sun has the largest mass of any object in our solar system, which is why the planets orbit about it. The gravitational law was discovered by Sir Isaac Newton Satellites Figure 2.5: The Moon as seen from Apollo 17. Satellites, such as the Moon, stay in orbit about their respective planets via the attraction of gravity. Version 1.0 1/26/06 Project Fulcrum 10

11 Activities 1. Print a sky map from in the Downloads section and pick the map for the appropriate month and year. Give these maps to the students to use with their parents at home. The maps show the different constellations and planets that should be visible along with the locations of visible planets in the night sky. This also can be used as a reference for the each month. 2. Print a Star Finder from spaceplace.nasa.gov under projects and have the students construct a Star Finder to experiment with at home. This website also has a lot of other science and space related games, projects, and information geared toward students Resources - This site has many links to interactive sky charts, a constellation index, and different space photos. It is a great site if you are curious or want more in-depth information. skyandtelescope.com/observing/ - This site has an interactive sky chart that can be customized to your location. The sky view can be rotated to see what is on the horizon and what is directly overhead Objective The student will be able to create a scale model of the solar system showing relative distance and size Key Concepts Students should understand that a scale drawing applies the same reduction ratio to whatever is being scaled. Students should be able to create a scale drawing of the planets sizes. Students should be able to create a scale drawing of the planets distances from the Sun. Student should be able to compare the planets dimensions or distances from the Sun using ratios Vocabulary Ratio The relation between to numbers expressed as 6 to 1, 6/1, or 6:1. This can be applied to scaled-down drawings with 1,000,000 kilometers to 1 inch, for example. Scale A proportion used to determine the relationship of a model to what it is representing. A scale of 1 inch on a map equals 4 miles on the Earth Activities 1. Toilet Paper Solar System Using the ratio of one sheet of standard toilet paper to 10 million miles, a scale model of the solar system can be created in the hallway. Using the following chart below, unroll your solar system and have a student stand at the location for each planet. (From Dr. Tim Slater, Montana State University, solar.physics.montana.edu/tslater) Version 1.0 1/26/06 Project Fulcrum 11

12 Celestial Object Number of Sheets from Sun # of Tissues from previous object # of Units (feet or yards) Sun Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune Pluto (avg. orbit) This could also be done with a piece of string or rope a little over 122 units long, with the units being either feet or yards depending on the space (see chart). Place a piece of tape in the planet s location so it can be wound up and reused next year. 2. Solar System Scale Model Using a long field or sidewalk, some stakes, and different sized balls to create a scale model of the solar system. Start with a Sun ball 11cm or about 4 inches in diameter at your starting point. Moving away from the Sun, mark and label the location of the planets. Place a ball of the correct size at each location as well. The table below shows the planet, distances from the Sun, and ball diameters. Set this activity up before hand and the walk the students from the Sun to Pluto. Planet Distance from Sun (yds) Approx. Planet Diameter (mm) Sun Mercury Venus Earth 13 1 Mars Jupiter Saturn Uranus Neptune Pluto Version 1.0 1/26/06 Project Fulcrum 12

13 2.4. Objective Students will be able to understand how the seasons and phases of moon are affected by the motion of the Earth and moon the moon are affected by the motion of the Earth and moon Key Concepts Understand how the days on Earth change because of rotation around a central axis Understand how it takes an entire revolution around the Sun for one year to pass on Earth. Understand how the angle of the Earth s axis and the revolution of the Earth around the Sun affect the seasons. Understand how the revolution of the Moon around the Earth changes the phases of the Moon Vocabulary Axis A straight line about which a body rotates or seems to rotate. The Earth s axis is slightly off from the North and South Poles and is tilted about 23.5 degrees. This accounts for the change in seasons as the Earth revolves around the Sun. Day - The length of time it takes a planet to rotate once about its axis. There are 24 hours in a day on Earth, but a day on Jupiter is less than 10 hours. Revolution The orbital path taken by the planets around the Sun. The Earth completes one revolution around the Sun in 1 year. Rotation The turning of a body around a central axis. The Earth completes one rotation around its axis in 24 hours. Year The length of time that it takes a planet to travel around the Sun. A year on Earth is 365 days, 5 hours, and 49 minutes; which is why an extra day is added every fourth calendar year. A year on Pluto is over 248 Earth years and a year on Mercury is only about 88 Earth days The Motion of the Sun. Figure 2.6: The Sun early in the morning (top), at noon The Day. Observations of the (middle) and E in the afternoon (bottom). behavior of the Sun over a long N S period of time show that some things do not change, even over the course W of many years. For example: E The Sun always rises from roughly the same direction (east) N S and sets in the opposite direction W (west) E In between rising and setting, the Sun follows a long arc. The N S Sun is furthest from the horizon W halfway between rising and setting. We call this position noon. We can use this periodic (regularly repeating) motion to define the day as the time from one noon to the next. The position of the Sun is different at different times of the day. A vertical pole placed into the ground casts a shadow. The shadow will be long in the morning and afternoon, and shortest when the shadow cast by the pole points south (or north) which happens at noon. Version 1.0 1/26/06 Project Fulcrum 13

14 Consider three different positions of the Sun, as shown in Figure 2.7. Remembering that shadow always points away from the Sun, we find that: In the morning, the Sun is in the east and the shadow points to the west. The shadow falls due north when the Sun it at its highest point. In the evening, the Sun is in the west, and the shadow is toward the east. The Week. The fact that there are seven days to the week is a result of there being seven stars/planets (The Sun, Moon, Mercury, Venus, Mars, Jupiter, and Saturn) visible to the naked eye. The days were named according to how long each took to move across the sky. Saturn s day became Saturday, Sun s day became Sunday, Moon s day became Monday. The remaining days are named after French, Italian, or German words for the remaining planets. The number seven acquired some of its mystique from there being seven known planets. The Seasons in Terms of the Position of the Sun as Seen from Earth. If you track the position of the Sun carefully for a year and use trees or telephone poles as references, you would notice that the Sun doesn t follow the same path every day. The path and the position of the Sun, change depending on the time of year. Figure 2.7 shows the different paths of the Sun at different times of the year. 2 The direction of the shadow when the Sun is directly overhead does NOT change day to day, but the directions of shadows at other times of the day do change. The Sun rises exactly in the east and sets exactly in N the west only twice each year. These special days are called equinoxes because the length of the day and the length of the night are approximately equal. The autumnal equinox in is the fall and the vernal equinox is in the spring. The positions of the sunrise and sunset move south as fall changes into winter. The steepness of the curve traced by the Sun does not change, nor does the rate at which the Sun moves along the path; however, the length of the curve becomes shorter. The Sun takes less time to travel the shorter path, which decreases the number of hours of sunlight during the winter months. The winter solstice, when the Sun takes the shortest path of the year through the sky, is around December 21, which is halfway between the equinox dates (typically September 23 and March 21). The winter solstice is the day with the fewest daylight hours. After the winter solstice, sunrise and sunset positions move northward, and days get longer as the path of the Sun gets longer. The summer solstice is the day when the Sun crosses the horizon at its most northerly position (usually around June 21). The summer solstice is the day of the year with the longest number of hours of sunlight. The process repeats every year. E Path in July W Path in December Figure 2.7: How the path the Sun takes through the sky changes with the seasons. S 2 You can see the path of the Sun as a function of day and month using the applet at or at Version 1.0 1/26/06 Project Fulcrum 14

15 The Seasons as Seen from Space. The year is divided into four parts by the two solstices and the two equinoxes. The solstices are the longest day and longest night, and the equinoxes are when night and day are equal. These define the starts of the seasons. The time between the spring equinox in 2003 (March 21) and the fall equinox in 2003 (September 22) is 184 days; however, the time between the fall equinox and the spring 2004 equinox (March 20) is 181 days. The equinox positions correspond to the Earth being on exactly opposite sides of its orbit. Why are there three days fewer in summer than there are in winter? The Earth moves a little faster in winter. The Earth is closest to the Sun (at perihelion) around January 4 and moving at its fastest speed. The half of the ellipse closest to the Sun is shorter as well, which gives rise to a difference of 3 days. Note that Earth is closest to the Sun at the winter solstice and furthest from the Sun at the summer solstice. The Earth rotates on an axis that is inclined 23 from the vertical toward the Sun, as shown schematically in Figure 2.8. The tilt of the Earth explains why days and nights vary in length, why seasons change and why climates vary with latitude. As the Earth orbits about the Sun, the Northern Hemisphere is oriented so that it is tilted toward the Sun in summer and away from the Sun in winter. Figure 2.9 shows the position of the Earth at different times of the year. axis 23 Figure 2.8: The Earth rotates on its axis. The beginning of a season is recognized from the length of the daylight period, the altitude of the Sun in the sky at noon, and the length of the shadow of a vertical stick at noon. On June 22 nd and Dec 22 nd, the Sun reaches its highest and lowest noon altitudes. In the summer, the North Pole is pointed toward the Sun, so there are more hours of daylight. The noon Sun is at its highest position of the year on the June 22 nd, and the shadow of a pole will be the shortest it will be all year. You can see from this picture why very northerly countries have periods during which the Sun does not set. Conversely, in the winter, the North Pole is pointed away from the Sun, so the hours of daylight are shorter, and on December 22 nd, the noon Sun is the lowest in the sky it will be all year. Version 1.0 1/26/06 Project Fulcrum 15

16 Autumnal Equinox Winter Solstice Summer Solstice 23 Because of the elliptical orbit, Earth is about 2.5 million kilometers closer to the Sun in January than its average orbit and about the same distance further away from the Sun in July. The Earth as a whole gets 6% more solar energy in January than in July. Clearly, the distance from the Sun is not as important as the effects of the tilted axis Hours and Minutes. The division of the day into 24 hours, the hour into 60 minutes and the minute into 60 seconds has a number of explanations. One possibility is that it is a result of the Babylonians using a base 60 number systems. 12 (the approximate number of daylight hours) would be 60/5. The Babylonians had a 360 (6*60) day year, which likely was a compromise between the 365 day solar year and the 354-day lunar year The Moon Phases of the Moon: Like the Sun, the Moon rises in the east and sets in the west. Unlike the Sun, the Moon takes on difference appearances different phases at different times of the month. Figure 2.10 shows the different phases of the Moon as seen from Earth. There are two crescent, gibbous, and half phases each month, but these phases are reflections of each other different. The amount of lighted area increases from the new Moon to the full Moon and decreases from the full Moon to the new Moon. The Moon is said to be waxing when changing from New Moon to Full Moon and waning when changing the Full Moon to New Moon. The phases are mirror images of each other. This chart is only good for the Vernal Equinox Figure 2.9: The seasons (drawing is not to scale). Remember that the Earth actually is closer to the Sun in the winter than it is in the Summer. New Moon Waxing Crescent First Quarter Waxing Gibbous Figure 2.10: Phases of the Moon. Version 1.0 1/26/06 Project Fulcrum 16 Full Moon Waning Gibbous Last Quarter Waning Crescent

17 Northern Hemisphere the effect is the opposite in the Southern Hemisphere The Month: The cycle of phases repeats itself about once every 29.5 days and this is how the month originally was defined. Many calendars were based on the phases of the Moon. The Metonic calendar (developed by an ancient Greek astronomer named Meton) is one of the mostused lunar calendars. Unfortunately, the lunar calendar is not commensurate with the solar calendar. This means that the number of complete cycles of the Moon does not evenly divide into the length of the year. The Metonic calendar is corrected seven months must be added every 19 years to keep the calendar in synchronization with the seasons. The year has a length of /19 months, which turns out to be nearly 365 days. The Hebrew calendar is based on the Metonic calendar, with each month beginning at or near the new Moon. The Moslem and Persian calendars are true lunar calendars and depend strictly on observation of the new Moon to begin a new month. This means that one year, summer might be in the equivalent of July, while 15 years later, summer would be in the equivalent of December. Figure 2.11 shows the phases in a different way. View the applet at phases/phases.html to see an animated version of this explanation Eclipses During an eclipse, a celestial object (like the Sun or the Moon) is blocked (as in the right picture of Figure 2.12). The blockage can be total, as shown in Figure 2.12 or partial. Solar eclipses are when the Sun is blocked and lunar eclipses are when the Moon is blocked. Total eclipses happen extremely rarely. A movie of a solar eclipse (a view of the Sun as seen from Earth) can be viewed at Figure 2.11: Phases of the Moon. The Sun is to the left. 3 The eclipses we see from Earth are the lunar eclipse, in which the Earth passes directly between the Sun and the full Moon such that the Earth s shadow falls on the Moon, and the solar eclipse, Lunar Eclipse: the Earth passes directly between the Sun and the Moon Sun Earth Moon Solar Eclipse: the Moon passes directly between the Sun and the Earth. Sun Moon Earth Figure 2.13: Lunar and solar eclipses. (Not to scale) Figure 2.12: A total eclipse of the Sun. 3 Version 1.0 1/26/06 Project Fulcrum 17

18 in which the Moon passes directly between the Sun and the Earth, as shown in Figure It takes about eight minutes for a solar eclipse to be completed and about 100 minutes for a lunar eclipse to be completed. In both, a shadow is cast that partially or fully obscures the Sun or Moon Precession In the second century BC, the Greek astronomer Hipparchus measured stars brightness and positions. The star catalogue he compiled was used for centuries. When he compared his observations with those made by astronomers over a century earlier, he found a systematic shift in the positions of the stars. The Earth is not a perfect sphere it is flattened, as if someone had squeezed the poles together (See Figure 2.14.) The equatorial diameter is 21 kilometers greater than the polar diameter. The squeezing wasn t perfectly symmetric either, so Earth actually is a lopsided spherical oblate. This lopsided shape is due to the rotation of the Earth about its axis, much like a piece of pizza dough flattens out when you spin it in the air. The flattened shape, the rotation of the Earth about its axis, and the orbiting of the Earth about the Sun combine to cause the Earth to precess that is, the axis about which the Earth rotates also moves, as shown in Figure Precession is much like the motion of a top - a top doesn t rotate with the axis standing straight up the axis actually moves around. A nice applet can be found at: Earth s' axis meets the celestial sphere at the North and South Celestial Poles. As the axis precesses, the locations of the poles change. The Earth s axis describes a cone. The axis will travel around this cone once every 25,800 years. The North Celestial Pole (NCP) is about 1 degree from Polaris. In 2100, the NCP will be the closest to Polaris at amount 27 arc-minutes. Two thousand years ago, Polaris was 12 from the NCP. (There is no bright star near the SCP at present) In 6,000 years the Earth's axis will point towards the star Alderamin in Cepheus, and in 12,000 years it will be near Vega in Lyra. NASA scientists studying the Indonesian earthquake of Dec. 26, 2004, have calculated that it slightly changed our planet's shape, shaved almost 3 microseconds from the length of the day, and shifted the North Pole. According to the latest calculations, the Dec. 26th earthquake shifted Earth's "mean North Pole" by about 2.5 centimeters in the direction of 145 degrees east longitude, more or less toward Guam in the Pacific Ocean. This shift is continuing a long-term seismic trend identified in previous studies. Equatorial diameter km Polar diameter km Figure 2.14: The equatorial bulge of the Earth. The degree of the bulge is exaggerated. Vega (future North Star) Polaris (current North Star) Figure 2.15: The precession of the Earth. Distances are not to scale. Version 1.0 1/26/06 Project Fulcrum 18

19 Activities 1. Moon Phases - Have the entire class sit in a circle around a single student who is holding a ball (the Moon) above his/her head. Give each student a piece of paper with a 6 inch circle in the center and the word Moon at the top. Turn the lights down (or off) and shine a flashlight (the Sun) at the ball in the center of the circle and stay in this position. Now have each student color in the dark part of the ball as they see it so there is a light part and a dark part of the appropriate size. Once everyone has finished their drawings, turn the lights on and have everyone turn the drawings toward the inside of the circle with the word Moon at the top. There should be a drawing that is all white directly in front of the person holding the flashlight with the moons getting more filled in you go around the circle to the halfway point where it will be all black. The white portions should get larger and larger until your back at the beginning. Make sure to also walk around the outside of the circle with the flashlight on the ball so each student can see the moon change phases. Note: Make sure that the flashlight isn t pointed directly into a student s eyes. 2. Earth s Seasons Mark an equator around a foam ball and then place a stick or pencil into the ball s South Pole. Have a student hold the ball at a slight angle (about 20 degrees) and walk around it with a flashlight. There are times when the upper half of the ball is getting more light and times when the lower half is getting more light, these are summer and winter, respectively, with spring and fall in between them. This could also be done with a globe tilted to about 20 degrees. Make sure to note that the Earth is really what rotates around the Sun. To make this more evident, one student could hold the Earth always tilted towards the front of the class and walk around another student with a flashlight always pointing at the Earth. It could also be pointed out that when it is summer in the Northern Hemisphere it is winter in the Southern Hemisphere and vice versa Resources Go to and click on Demonstration of Moon Phases. When the applet loads, select Both from the pull down menus, and click Animate. This may not be suitable for the students, but will give you a good idea of what is happening. Notes: The dark side of the Earth is the nighttime side with the point furthest from the Sun being Midnight; the closest point to the Sun is noon. This demo requires that Java be installed on the computer, if it is not already installed. This can be downloaded from java.sun.com for free. Also, the Moon Phase Activity in the In-Class Activites section of has another moon phase activity that uses the students heads as Earth and a styrofoam ball as the moon. There are also other space related activities available on this website. An applet at: shows a complete lunar calendar Objective The student will be able to develop an understanding of asteroids, meteoroids, and comets in our solar system as well as stars beyond our solar system Key Concepts Understand where asteroids and the asteroid belts are located. Be able to differentiate between comets, meteors, meteorites, meteoroids, and craters that can be formed when an impact occurs. Know that our galaxy is the Milky Way Understand the importance of the North Star Version 1.0 1/26/06 Project Fulcrum 19

20 Understand that a light year is a unit of distance and appreciate how large a distance it is Vocabulary Asteroid Any of the numerous small bodies in space that also revolve around the Sun. Most are located between Mars and Jupiter, and can be a few to several hundred kilometers across. Asteroid Belt The region between Mars and Jupiter where most asteroids are located. (See Figure 2.1.) Comet A body in space that is only observed in the part of its orbit that is relatively close to the Sun. They consist of a head followed by an elongated tail made of mostly vapor. Crater A bowl shaped depression typically formed during the impact of a meteoroid with a planet or moon. Galaxy Any of the large number of groupings consisting of stars, gas, and dust that make up the universe. Light-year The distance light travels in space in one Earth year; roughly 5.88 trillion miles. Meteor A bright tail or streak that is seen when a meteoroid burns up in the atmosphere, also called a shooting star. Meteorite A stony or metallic mass that has fallen to the Earth s surface from space. Meteoroid A solid body moving in space that is smaller than an asteroid but larger than a speck of dust. A meteoroid becomes a meteor if it burns up in the atmosphere or a meteorite if it falls to the Earth s surface. Milky Way The galaxy that contains the solar system, it can be seen at night as a wide band of faint light in the sky. North Star The northern axis of the Earth points towards it in the night sky. It can be found as the end of the handle on the Little Dipper constellation. Universe Everything that is contained in space; including all the planets, the stars, and the galaxies. Asteroids in an asteroid belt A comet traveling through space Version 1.0 1/26/06 Project Fulcrum 20

21 Meteor or shooting star burning up in the Earth s atmosphere Meteorite found on Earth Crater created by a meteorite hitting the Earth. This crater is 20 miles west of Winslow, AZ. The Milky Way Resources is a gallery of crater pictures. Version 1.0 1/26/06 Project Fulcrum 21

22 3. Nature and History of Science 3.1. Astrology Astrology vs. Astronomy. Astrology is the belief that events on Earth are influenced by the motions of the planets. Astrology started 4000 years ago in Babylonia and became part of the Greek culture when they conquered that part of the world. Eventually, people came to believe that the positions of the Sun, Moon, and planets at a person's birth were especially significant. This was one of the driving forces for developing models that could predict the positions of the planets and the stars. Astrologers focused on predicting the future of human events and astronomers focused on predicting the motion of the planets, Sun, and Moon. Many early astronomers, however, felt that being able to predict the motions of the planets Figure 3.1: The position of the Sun relative to the zodiac at two different times of the year. would allow them to more accurately predict people s futures. A number of famous astronomers in the past also were astrologers casting horoscopes was one way they supported themselves financially. Patrons were much more willing to pay for advice about the future than they were for scientific discovery. Tycho s interest in making more accurate measurements was initiated in part because of problems with his astrological calculations due to inaccurate observational tables. Although many ancient astronomers also were astrologers, modern astronomers do not believe that the motions of the planets affect the future Is Astrology a Science? Astrology assigns you a sign, according to the zodiac constellation the Sun was in at your birth. Figure 3.1 shows you one problem with this, which is that the Sun spends more time in large constellations like Scorpio and Virgo than in small constellations like Libra and Cancer. The signs, however, all cover 30 or 31 days. Astronomers like to point out that there actually is a 13 th constellation. The Sun spends about 10 days in the constellation of Scorpius, and then 20 days in Ophiuchus (the serpent holder). This constellation isn t included in astrology. Because of the Earth s precession, the Sun was probably in the constellation before your official sign because the spring equinox moves westward one degree every 72 years. Three thousand years ago, the Sun entered the house or constellation, of Virgo in August. Astrological forecasts today still assume that this is where the Sun is but it actually is in the house of Leo in August now. A horoscope includes the position of each planet relative to the zodiac and with respect to the person at the time of his/her birth. There are some standard rules for creating a horoscope, although many have not changed for thousands of years despite the dramatic improvements in Version 1.0 1/26/06 Project Fulcrum 22

23 our knowledge of how the planets and stars move. There also is a strong subjective component in how much emphasis an astrologer will give to each rule in developing the horoscope. Two astrologers can cast different horoscopes for the same person how do you decide which to believe? Activity: For one week, consult four different horoscopes (you may have to find them on the web make sure they are from different people and not just copies of syndicated horoscopes). Compare the horoscopes to each other, and compare them to what happens to you each of those days. The question of the mechanism by which the planets influence people is unknown. The only forces that exist between planets and people are electromagnetic and gravitational. We will calculate in the next unit that the gravitational force due to a doctor delivering a baby is greater than the force of gravity due to any of the planets. What types of tests could be done to check whether astrology has a scientific basis? For example, one might expect that leaders would share some astrological characteristics, but studies of the birthdates of presidents or governors, etc. show that they are randomly distributed between the signs. An episode of NOVA (on PBS) showed a researcher working with a group of college students all professing a belief in astrology. The researcher gave each person their own individual horoscope. Each person found some event in their day that fit their horoscope. The researcher then asked each person to give their horoscope to the person behind them. The students discovered that these new horoscopes also described some event in their day. The French researcher Michel Gaugelin sent a horoscope of a mass murderer to 150 people but told each one that the horoscope was prepared just for him or her. Over ninety percent of them said they could see themselves in that horoscope. The Australian researcher Geoffrey Dean substituted phrases in the horoscopes of 22 people that were opposite of the original phrases in the horoscopes. Ninety-five percent of time they said the horoscope readings applied to them just as well as to the people to whom the original phrases were given. Version 1.0 1/26/06 Project Fulcrum 23