6th Grade Astronomy. Third Edition: by Adam Chantry (Based on previous works by Ted Williams & Dr. Gerald Mallon)

Transcription

1 6th Grade Astronomy Third Edition: by Adam Chantry (Based on previous works by Ted Williams & Dr. Gerald Mallon) Methacton School District 2017

2 Scale Solar System Model Hike Approximate Scale 1:5.768Billion **Fill in the Scale Time for light to travel from sun as we walk. Body Real Diameter in Km Scale Diameter in mm Average distance from Sun in KM Scale Average distance from Sun in meters Time for light to travel from sun Scale Time for light to travel from sun Sun 1,391, NA NA NA NA Mercury 4, ,950, min. Venus 12, ,110, min. Earth 12, ,570, min. Mars 6, ,840, min. Jupiter 142, ,140, min. Saturn 116, ,427,000, hr min. Uranus 46, ,870,300, hrs min. Neptune 45, ,499,900, hrs. 6 min. Pluto 2, ,913,000,000 1, hrs. 30 min. Alpha Centauri (Nearest Star) 1,531, ,320,000,000,000 7,003, years Speed of Light = 299,792,458 m/s Scale Speed of Light= approximately 52 m/s What is the difference between a model and a scale model? Why is it important to know the scale of a model? Why is it hard to have scale models of our solar system in text books? 1

3 Day One Vocabulary Match the words at the bottom of the page to the definitions in the chart. A drawing which has been reduced or enlarged from its original size, to a specified scale A group of related parts that move or work together. The place where someone or something is in relation to other people or things. 299,792,458 meters per second (186,000 miles per second) The distance light travels in one year. 9 trillion meters (6 trillion miles) Speed of Light, Scale Model, System, Orientation, Light Year Use the space below to draw a sketch of our solar system. 2

4 Planet Information Terrestrial Planets: Planets that are composed primarily of silicate rocks and/or metals. Mercury Venus Earth Mars Size (Diameter in miles) 3,032 mi (4,879 km) 7,520.8 mi (12,104km) 7,917.8 mi (12,742km) 4,212 mi (6,779km) Avg. Distance from Sun million mi (0.39 AU) 67.2 million mi (0.723 AU) 93 million mi (1 AU) million mi (1.524 AU) Rotation Period (Earth Time) 58d 15hr 30m 166d 18hr 24hr 1d 0hr 40m Orbital Period (Year in Earth Time) 88d (0.24y) 225d (0.62y) d (1.0y) 687d (1.88y) Density g/ cm g/ cm g/ cm g/ cm 3 Avg. Surface Temperature to to to to 70 Moons 0 (none) 0 (none) 1- The Moon (Luna) 2,158 mi diameter 2 - Phobos (14mi diameter) Demos (8mi diameter) Other Interesting Facts 3

5 Planet Information Jovian Planets: Jovian means Like Jupiter. These four planets are primarily made of gas and ice. They are also referred to as the Gas Giants. Jupiter Saturn Uranus Neptune Size (Diameter in miles) 86,881.4 mi (139,822km) 72,367.4 mi (116,464km) 31,518 mi (50,724km) 30,599 mi (49,244km) Avg. Distance from Sun million mi (5.2 AU) million mi (9.6 AU) Billion mi (19.2 AU) Billion mi (30.1 AU) Rotation Period (Earth Time) Orbital Period (Year in Earth Time) 9h 48m 10h 14m 17h 14m 19h 6m 12 years 29 years 83 years 165 years Density 1.33 g/ cm g/ cm g/ cm g/cm 3 Avg. Surface Temperature Moons 67 (That we know of) 53 (That we know of) 27 (That we know of) 13 (That we know of) Rings Rings Rings Rings Other Interesting Facts 4

6 Planet Information Dwarf Planets: celestial bodies resembling small planets but lack technical criteria required to be planets. Pluto Ceres Size (Diameter in miles) 1,475 mi 590 mi Distance from the Sun Rotation Period (Day in Earth Time) Orbital Period (Year in Earth Time) 3.67 Billion mi (40 AU) ( Billion Miles) 6d 9h 36m 248y 257 Million mi (2.77 AU) 9h 4y 221d Density ( g/ cm 3 ) 1.86 g/cm g/ cm 3 Avg. Surface Temperature Moons 5 Moons 0 (none) Other Interesting Facts 5

7 Graphing Activity In the space below: Graph the relationship of the distance of the object from the Sun and the orbital period. Be sure to give your graph a title and determine the correct scale for the x and y axises. 6

8 Apparent or Real When it come to life, thing are not always as they appear. This is true for life on Earth and definitely true for the study of the universe. Stars appear to be tiny dots of light in the sky. The sky appears to move slowly around us. The sun appears to rise in the east and set in the west. The true nature of these thing turns out to be quite different from what our eyes show us. To get used to the fact that we can not always believe our eyes, look at the images on this page and see if you can tell the difference between what is apparent and what is real. -Dr. Gerald Mallon What do you see in the above picture? How many triangles can you find? 7

9 How many circle do you see? Are these rows and columns straight or bent? 1 Astronomy vs astrology? What s the difference between astrology and astronomy? The words are similar and can be confused, but are very different things though a closer look at the history of the words reveals that this hasn t always been the case. The difference between astronomy and astrology Let s clear this up first. Astronomy is the branch of science which deals with celestial objects, space, and the physical universe as a whole. If you re thinking about the academic study, stargazers, telescopes, and the like, then the word you need is astronomy. Supernovae are among the most spectacular phenomena known to astronomy. An inquiry into the effect of light pollution on astronomy was published last year. She wrote her doctoral thesis in the field of astronomy. Astrology, on the other hand, is the study of the movements and relative positions of celestial bodies interpreted as having an influence on human affairs and the natural world. If you are writing about people using stars or planets to predict favourable or unfavourable events happening to humans, then astrology is the correct word. The planets, signs, houses and aspects are the nuts and bolts of astrology. In astrology Mars represents the compelling force of action and initiative. It is unlikely that he ever practised astrology in the sense of drawing up charts and interpreting them. Etymology and changing use Ancient observers of the heavens developed elaborate systems of explanation based on the movements of the sun, moon, and planets through the constellations of the zodiac, for predicting events and for casting horoscopes as well as using the sun, moon, stars, and planets astronomically to form the basis of timekeeping and navigation. By 1700 astrology had lost intellectual credibility in the West, but continued to have popular appeal. While astronomy remains an academic pursuit, astrology is now widely considered a pseudoscience. This distinction has certainly not always been present. Both words relate to astron, the Greek for star. Astronomy ultimately comes from the Greek astronomos astronomer, or more literally someone who classifies the stars, while astrology means study of stars, but the words have sometimes been used more or less interchangeably though that is no longer the case, and they now have entirely distinct meanings. In its earliest uses in English, astrology was used to mean the practical application of the (medieval) art or science of astronomy that is, astronomy was theoretical and astrology was practical. Astrology originally included the calculation of natural phenomena and meteorological events (such as the measurement of time and the times of tides and eclipses) that are now considered the domain of astronomy. This was termed natural astrology, while judicial astrology covered much the 1 "Astronomy vs astrology? OxfordWords blog." 30 Mar. 2016, Accessed 29 Dec

10 same ground that astrology does today: the supposed art of foretelling or counselling in human affairs by interpretation of the motions of the planets and stars. In modern English, the division between astrology and astronomy is fixed, and it s worth making sure you know which is which before you use either of them. The Apparent night Sky Draw the apparent shape of the night sky. Add stars to the night sky. Draw them as an astronomer might: by drawing discs ( NOT ). The brighter the star, the larger the disc. Label the HORIZON Label the ZENITH Based on your observations in the planetarium: Are there more dim stars or bright stars in the night sky? How many stars can you SEE with your unaided eyes in the night sky? What is the APPARENT shape of the sky? 9

11 Apparent Skies Around the World Label the Equator Draw the APPARENT shape of William s and Caroline s skies. What CONSTELLATION can William see? Can Caroline see the same constellations as William? Explain why or why not What CONSTELLATION can Caroline see? Why do you think The North Star is called The Pole Star? 10

12 Day Two Vocabulary Match the words at the bottom of the page to the definitions in the chart. a constellation that is only above the horizon (thus visible) for part of the year. A group of constellations that never set below the horizon from the viewer's perspective. a group of stars forming a recognizable pattern that is traditionally named after its apparent form or identified with a mythological figure. Modern astronomers divide the sky into eighty-eight constellations with defined boundaries. Any pattern of stars recognized in the Earth's night sky. It may be PART of an official constellation or it may be composed of stars from more than one constellation. These are NOT constellations. (Examples: Orion's Belt and The Big Dipper) The act or process of moving or turning around a central point. Objects in the sky appear to rise in the East and set in the West each day. This apparent daily motion is a reflection of the Earth's rotation about its axis. The study of the Universe and the changes that take place in and around all objects moving through space. The study of the movements and relative positions of celestial bodies interpreted as having an influence on human affairs and the natural world. Using the sky to predict the future. Seeming REAL or true, but not necessarily so. Actually existing as a thing or occurring in fact; NOT imagined or supposed. The point above the observer on the imaginary sphere against which celestial bodies appear to be projected The imaginary line where the earth or sea seems to meet the sky. A real or imaginary line on which something rotates. 11

13 Circumpolar Constellation, Asterism, Rotate,Axis, Daily Motion,Seasonal Constellation, Astronomy, Apparent, Real, Zenith,Astrology, Horizon, Celestial Equator, Constellation, Rotation and Revolution Draw the Apparent shape of Giovanni Cassini s and Isaac Newton s skies What is the time of day for Giovanni? What is the time of day for Isaac? How long will Giovanni have to wait for the Earth to ROTATE to get to where Isaac is? 12

14 How long will Isaac have to wait for the Earth to ROTATE around its access and get him back to the same position? How long will it take for the Earth to REVOLVE around the Sun and get to Point X? Seasons Observations (Eagleville 40 N Latitude) Azimuth: The angular distance measured clockwise from North on the horizon to the point at which a vertical line passes through an object intersects the horizon. Altitude: The angular distance above the observer's horizon of a celestial object. Data Table: Date Sunrise Position (NSEW) Degrees Azimuth Sunrise Noon Position (NSEW) Degrees Altitude at Noon Sunset Position (NSEW) Degrees Azimuth Sunset Observation Sketch: 13

15 Why do you think the Sun s path in the sky changes throughout the year? Reason for the Season Use the space below to draw a diagram/model (Not to Scale) that you believe could explain the Season Observations we made on the previous page. Use the lines below to write a detailed description of your model above 14

16 Reason for the Season Label each Earth with the following seasons beginnings for the NORTHERN hemisphere: Summer Solstice, Winter Solstice, Vernal (spring) Equinox, Autumnal (fall) Equinox Put the date for each Equinox and Solstice next to each Earth. When Earth is closest to the sun, what season is the northern hemisphere experiencing? The Earth s axis is tilted in relation to its orbit by how many degrees? How many days does it take for the Earth to go from one Winter Solstice to the next? 15

17 Explain why the Earth s north pole always point in the same direction no matter where it is in it s orbit? Predictions Around the Globe Make your prediction of the path of the sun from the given locations on the given date. (Hint: Sketch a model of the Sun/Earth system to help you make your prediction.) On the Equator 12/21 On the Tropic of Cancer (23.5 N Lat.) 6/21 16

18 2 What is the significance of the Tropic of Cancer, Tropic of Capricorn, Arctic Circle and Antarctic Circle? (Beginner) The Tropic of Cancer is the circle marking the latitude 23.5 degrees north, where the sun is directly overhead at noon on June 21, the beginning of summer in the northern hemisphere. The Tropic of Capricorn is the circle marking the latitude 23.5 degrees south where the sun is directly overhead at noon on December 21, the beginning of winter in the northern hemisphere. When the lines were named 2000 years ago, the Sun was in the constellation of Capricorn during the winter solstice and Cancer during the summer solstice (hence the names). Now due to the precession of the equinoxes the Sun is no longer in these constellations during these times, but the names remain. The equator is the circle where the Sun is directly overhead at noon on the equinoxes. The Arctic and Antarctic Circles are located at ±66.5 degrees latitude. Note that equals 90 degrees. This means that on December 21, when the Sun is directly over the Tropic of Capricorn at noon, it will NOT be visible from the Arctic Circle. So above the Arctic Circle, there is a period during the winter when the sun remains below the horizon. The same is true of the Antarctic Circle during Southern Hemisphere winter. On June 21st, when the sun is directly over the Tropic of Cancer at noon, it is not visible from below the Antarctic Circle. 2 "What is the significance of the Tropic of Cancer, Tropic of Capricorn..." 27 Jun. 2015, ircle-and-antarctic-circle-beginner. Accessed 29 Dec

19 Knowing what you know now about how latitude s relationship to the Sun and seasons, at what latitude would you like to live and why? Day Three/Four Vocabulary Match the words at the bottom of the page to the definitions in the chart. The path of an object around a particular point in space, for example the path the Moon takes around the Earth. Orbits are determined by gravity, and are often 'elliptical', the shape of an oval. Divisions of the year, defined by changes in weather and the position of Earth in its orbit around the Sun. The seasons occur because of the tilt in the Earth's axis with respect to the plane of Earth's orbit. A great circle of the celestial sphere passing through the celestial poles and the zenith. The angular distance above the observer's horizon of a celestial object. The angular distance measured clockwise from North on the horizon to the point at which a vertical line passes through an object intersects the horizon. The inclination angle of a planet's rotation axis in relation to its orbital plane. 18

20 The brightest star in the constellation Ursa Minor (not brightest in the night sky); at the end of the handle of the little dipper; the northern axis of the earth points toward it. Also Known As (AKA): North Star, pole star, polar star, polestar. Either of the two times each year (as in spring around March 21 and in fall around September 23) when the sun's center crosses the equator and day and night are everywhere of equal length. Either of the two times in the year, the summer solstice and the winter solstice, when the sun reaches its highest or lowest point in the sky at noon, marked by the longest and shortest days. When something is moving in a circle around another object, such as the way the Moon Circles the Earth, it is said to revolve around that object. The apparent motion of the Sun a little towards the East each day as seen with respect to the background stars. This daily eastward drift is <1 per day (there are 365 days in a year, but only 360 in a circle). Tilt,Orbit, Altitude, Azimuth, Polaris, Equinox, Solstice, Meridian,Revolve, Season, Annual Motion 3Why is the Solar System Flat? We all know that the Earth, the other planets and their moons all revolve around the Sun in elliptical orbits. However, have you ever stopped to wonder why these celestial objects move around the Sun in such a way that the Solar System appears to be lying on a plane, rather than going every which way? We have learned in our classes, and it is common knowledge, that nature prefers spherical orientations. From the tiniest drop of water in zero gravity to the shape of our planet, spheres are nature s favorite shape. Even the Sun, the largest object in our cosmic neighborhood, is also you guessed it a sphere! So why is it that all these planets, asteroids, meteors and moons chose to lie in a plane, endlessly circling in a two-dimensional dance? 3 "Why Is the Solar System Flat? - Universe Today." 30 Dec. 2015, Accessed 31 Dec

21 Think about Saturn s rings, which are also disc-like. Even the asteroid belt lies in a flat plane. This is not a strange exception of our Solar System either; other galaxies billions of light-years away are oriented in a similar way. The Milky Way, our home galaxy, is a group of nebulae, stars and rocks flatly suspended in space due to mutual gravitational attraction. The Origins of Our Solar System We can trace the origin of our solar system to a massive shapeless blob of matter floating through space about 4.6 billion years ago. The particles in this blob gradually began to move closer due to gravity, and whenever there are multiple particles and powerful gravitational forces, there are also (Continued on next page) collisions. These collisions and the subsequent trajectories of these particles are random, making them impossible to predict. Although these objects move randomly, the one thing that remains constant is a force called Angular Momentum. The Solar System is an isolated system in itself. The galaxy is also an isolated system, since the gravitational effect of other cosmic objects is negligible. In an isolated system, the total Angular Momentum has to be conserved. This physical quantity is constant around a fixed axis. This axis is a point in 2-dimensional space, and in our world, which exists in 3 dimensions, this axis turns out to be a line. The system rotates along a plane that is perpendicular to the axis. Therefore, whenever particles collide, they may move in any direction, but all the up and down motion cancels out, always following the rule that the total spin in that plane must be constant. Over time and after countless collisions, these particles lose their freedom in everything except 2-dimensional space, thereby aligning themselves in a plane. 20

22 This is extremely fortunate for us, since we needed all those particles to come together so that planets and stars could be born. Otherwise, the same result would have been achieved, but it would have taken much more time. Furthermore, in terms of cosmological events and fans of stargazing, we wouldn t experience eclipses nearly as often, due to the low probability of linear alignment between planets in a spherical system. Scientists have found many solar systems in the galaxy that are even more planar than ours, while some others have huge differences between their ideal and actual planes. This variation might be because they are relatively young or have had particularly violent histories. Our ancestors once believed that the world was flat; little did they know that the only flat thing about Earth is its larger position within the ocean of stars. In your own words, explain briefly (2-3 sentences) why the solar system is flat. 4 Why do the planets orbit the sun? (Beginner) Why do the planets rotate around the Sun? First, please note that "rotate" actually is used to describe an celestial body's spin, and "revolve" is used to describe its orbital motion. For example, the Earth completes one rotation about its axis about every 24 hours, but it completes one revolution around the Sun about every 365 days. Anyway, the basic reason why the planets revolve around, or orbit, the Sun, is that the gravity of the Sun keeps them in their orbits. Just as the Moon orbits the Earth because of the pull of Earth's gravity, the Earth orbits the Sun because of the pull of the Sun's gravity. Why, then, does it travel in an elliptical orbit around the Sun, rather than just getting pulled in all the way? This happens because the Earth has a velocity in the direction perpendicular to the force of 4 "Why do the planets orbit the sun? (Beginner) - Curious About..." 31 Jan. 2016, Accessed 31 Dec

23 the Sun's pull. If the Sun weren't there, the Earth would travel in a straight line. But the gravity of the Sun alters its course, causing it to travel around the Sun, in a shape very near to a circle. This is a little hard to visualize, so let me give you an example of how to visualize an object in orbit around the Earth, and it's analogous to what happens with the Earth and the Sun. Imagine Superman is standing on Mt. Everest holding a football. He throws it as hard as he can, which is incredibly hard because he's Superman. Just like if you threw a football, eventually it will fall back down and hit the ground. But because he threw it so hard, it goes past the horizon before it can fall. And because the Earth is curved, it just keeps on going, constantly "falling," but not hitting the ground because the ground curves away before it can. Eventually the football will come around and smack Superman in the back of the head, which of course won't hurt him at all because he's Superman. That is how orbits work, but objects like spaceships and moons are much farther from the Earth than the football that Superman threw. (We're ignoring air resistance with the football example; actual spacecraft must be well above most of a planet's atmosphere, or air resistance will cause them to spiral downward and eventually crash into the planet's surface.) This same situation can be applied to the Earth orbiting the Sun - except now Superman is standing on the Sun (which he can do because he's Superman) and he throws the Earth. The next question, then, is how did Earth get that velocity, since in real life there's no Superman throwing it. For that, you need to go way back to when the Solar System formed. Use the space below to list questions you have about gravity: Newton s Cannons Isaac Newton was a great scientist and mathematician who lived more than 300 years ago. He understood and wrote about many of the laws of motion that we see at work every day. To explain how one body can orbit another, he asked his readers to imagine a cannon on top of a very, VERY tall mountain. (Our cannon is on a very tall, imaginary lifter that goes up and down, but it is the same idea.) The cannon is loaded with gunpowder and fired. The cannonball follows a curve, falling faster and faster as a result of Earth's gravity, and hits the Earth at some distance away. What if we use more gunpowder? Here's what might happen: (Note that these amounts of gunpowder are just imaginary, not meant to be precise! Also, we are ignoring the fact that the air would cause drag on the cannonball and slow it 22

24 Amount of Gunpowder What Happens 2 bags of gunpowder: Cannonball goes faster and gets farther before gravity pulls it back to Earth. 3 bags of gunpowder: Cannonball is going so fast that it falls all the way around the world. It is in orbit! 4 bags of gunpowder: Cannonball orbits Earth again, but goes even higher at the peak of its arc. 5 bags of gunpowder: Cannonball is going so fast it completely escapes Earth's gravity and heads out into space, maybe to an asteroid or Mars or Jupiter! The same thing happens when the Space Shuttle or a satellite is launched into orbit. The rocket boosts the spacecraft up to the height of a "very tall mountain" and also gives the spacecraft its forward speed, like the gunpowder gives the cannonball. So the spacecraft just falls all the way around the Earth, never hitting the surface. The curve of the spacecraft's path is about the same as the curve of Earth's surface. So astronauts orbiting Earth aren't really weightless, they are just falling... and falling, and falling! How orbits work depends on basic laws of physics, as Newton described them. Newton s Cannons 23

25 Gravity and Orbits 24

26 Use the space below to draw a diagram/model (Not to Scale) that you believe could explain the Gravity observations and discussions we had in class. Links to models: Use the lines below to write a detailed description of your model above: Sun s Annual Motion Through The Zodiac 25

27 Label each Earth in the model with the dates of the Solstice or Equinox. What constellation would the Sun appear to be in during the Summer Solstice? What constellation would the Sun appear to be in during the Winter Solstice? What Constellation would the Sun appear to be in during the Spring (Vernal) Equinox? What constellation would the Sun appear to be in during the Fall (Autumnal) Equinox? 26

28 Sun Signs: Astronomical vs. Astrological Astrologers today are working with a dating scheme that has been outdated for over two millenia--and which was never particularly accurate to begin with. The traditional dates for the positions of the Zodiac constellations are simply incorrect. But modern astrologers don't actually observe the sky the way ancient astrologers did. They simply go by ancient charts based on the position of the Sun in the stars over 2000 years ago. As the following table indicates, the traditional dates for the Sun's position in the Zodiac are not only out of sync with the actual sky, but they are artificially separated into 30-degree segments to make each sign last an average of 30 days. As you can see in the right side of the table, the signs are anything but evenly distributed across the sky. You will also notice that there is in fact a thirteenth constellation--ophiuchus--which is ignored by traditional Astrology. TRADITIONAL ASTROLOGICAL DATES ACTUAL ASTRONOMICAL DATES TODAY (c C.E.) Constellation Date Span Days Constellation Date Span Days Aries 21 Mar - 19 Apr 30 Aries 19 Apr - 13 May 25 Taurus 20 Apr - 20 May 31 Taurus 14 May - 19 Jun 37 Gemini 21 May - 20 Jun 31 Gemini 20 Jun - 20 Jul 31 Cancer 21 Jun - 22 Jul 32 Cancer 21 Jul - 9 Aug 20 Leo 23 Jul - 22 Aug 31 Leo 10 Aug - 15 Sep 37 Virgo 23 Aug - 22 Sep 31 Virgo 16 Sep - 30 Oct 45 Libra 23 Sep - 22 Oct 30 Libra 31 Oct - 22 Nov 23 Scorpio 23 Oct - 21 Nov 30 Scorpius 23 Nov - 29 Nov 7 Ophiuchus 30 Nov - 17 Dec 18 Sagittarius 22 Nov - 21 Dec 30 Sagittarius 18 Dec - 18 Jan 32 Capricorn 22 Dec - 19 Jan 29 Capricornus 19 Jan - 15 Feb 28 Aquarius 20 Jan - 18 Feb 30 Aquarius 16 Feb - 3/ Pisces 19 Feb - 20 Mar Pisces 12 Mar - 18 Apr 38 27

29 Day Five/Six Vocabulary Match the words at the bottom of the page to the definitions in the chart. A force which tries to pull two objects toward each other. Anything which has mass has a gravitational pull. The more massive an object is, the stronger its gravitational pull is. Earth's gravity is what keeps you on the ground and what causes objects to fall. Gravity is what holds the planets in orbit around the Sun and what keeps the Moon in orbit around Earth. The closer you are to an object, the stronger its gravitational pull is. Gravity is what gives you weight. It is the force that pulls on all of the mass in your body. An imaginary sphere surrounding the Earth. Astronomers use it to help explain where objects are in the sky. Events that happen in a particular order, one following the other, and are often repeated. Seasons occur in a cyclical pattern. The path that the Sun, Moon, and planets follow in the sky. Cyclical Pattern, Celestial Sphere, Gravity, Ecliptic Path Use the space below to draw a model that helps you to understand why the sun appears to move through the constellations in the sky throughout the year. 28

30 The Moon Faces Earth Faces Away from Earth If you look up at the Moon night after night you will notice that it appears to change. It goes through all of its PHASES from NEW, to CRESCENT, to FULL, back to CRESCENT, and back to NEW. This CYCLICAL pattern repeats over and over. However, If you observe the features on the surface of the moon closely throughout this pattern, you will notice that these features never change. This means that there is an entire HEMISPHERE of the moon that we can not see from here on Earth. How can that happen? 29

31 Before Studying about the moon, please answer the following questions: 1) In the space below, draw a picture of the moon the way you last remember seeing it. Focus on the shape and anything you remember from the surface. 2) Explain in your own words why the Moon APPEARS to change its shape/phase: 30

32 The Moon s Phases The brightest object in our night sky is the moon: Earth s only natural satellite. With a pair of binoculars or a small telescope, you can see that the moon is covered with round craters, huge mountains (some over 6,000m high), and dry lava beds (dark areas called maria or seas). As you look at the moon, the features seem sharp because the moon has no atmosphere to distort your view. At any one time, half of the Moon s surface faces the sun and REFLECTS the Sun s light. The other half faces away from the Sun and is in darkness. (The side facing the Sun is always changing.) As the moon revolves around the Earth and the Earth revolves around the Sun, the relative positions of Earth, Moon, and Sun constantly changes. Because of these changes, we see different amounts of the Moon s surface being illuminated by the Sun during the month. The different shapes that the apparent moon (caused by the amount of the Moon s lit surface we see from Earth) are called PHASES. As the moon circles the Earth, it seems to change shape from day to day. Long ago, people discovered the pattern of its changes. They observed that this pattern was repeated, moon after moon, in about 29.5 days. This pattern was called a Moonth, but is now referred to as a month. Changes which occur regularly like this are called cyclical or are said to move in cycles. Because of the changing position of the moon around the Earth, the Moon s apparent shape constantly changes. Depending on how much of the lighted side of the moon that we see, the moon s shape will vary in appearance from a banana-like CRESCENT moon, to an orange slice-like QUARTER moon, and a ball-like FULL moon. This change occurs in regularly every 29.5 days. Below is the correct order of the phases of the Moon. The dotted circles represents the New Moon phase when the illuminated side of the Moon is not visible in the night sky. Notice how the cyclical pattern starts where it began with the New Moon. In order to practice getting the Moon s phases into the proper order, try the following activity. Draw each of the phases pictured above on a separate sheet of paper or index cards (or cut out the phases on the last page of this packet). Without looking at this sheet, try to get the pictures in the proper order. When finished, check your work with the diagram above. 31

33 Drawing the Phases Half of the sphere of the moon is always illuminated by the sun. As the Moon orbits around the Earth different amounts of the illuminated half are visible from the surface of the Earth. This causes the Moon s APPARENT change in shape to people on the Earth s surface. In the boxes below, draw the shape the moon would appear from earth. The write the phase name ON TOP of the box. Other than appearing to change shape in our night sky, what else does the Moon do for the Earth. In the space below list your ideas of how else the Moon may affect the Earth. 32

34 Eclipses: Solar and Lunar According to the diagram on the previous page the Moon gets in between the Sun and Earth once every 29.5 days. This should result in a SOLAR ECLIPSE. Also, the Earth gets in between the Sun and the Moon once every 29.5 days. This should result in a LUNAR ECLIPSE. Despite this observation we do not see eclipses every month. It is known that eclipses are fairly rare (Solar about 1 in 18 months and Lunar 2-4 per year). In the space below: explain why you think we do not see eclipses (lunar or solar) every month, then draw a diagram that illustrates you thinking. Illustration 33

35 Eclipses of the Sun and Moon An ECLIPSE is the blocking of something from sight. ECLIPSES of the Sun and Moon occur when the Earth, Moon, and Sun line up exactly. However, because the Moon s orbit is slightly tilted (about 5 )to the plane of the Earth s orbit, ECLIPSES do not happen very often. Usually, the Moon s shadow (caused by the Moon blocking the Sun s light) is either above or below the Earth and a Solar Eclipse does not occur. Solar Eclipses only occur about every 18 months or twice in 3 years. Similarly, the Earth s shadow (caused by the Earth blocking the Sun s light to the Moon) is either above or below the Moon and a Lunar Eclipse does not occur. Lunar Eclipses only occur 2 to 4 times a year. Below are diagrams showing the positions of the Earth, Sun, and Moon for both SOLAR and LUNAR ECLIPSES. A Solar Eclipse is when the sun is blocked from sight on Earth. Solar Eclipses can be Total, Partial, or Annular. A Lunar Eclipse is when the Moon moves into the Earth s shadow and does not reflect as much light as usual, making it darker or even a red color. Lunar Eclipses can be Preumbral, Partial, or Total. 34

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37 Before learning about tides, take a few minutes to write down the things you know about tides and why you think they happen. Think about how often the occur, where they occur, what time of day they occur, and anything else you may know. Us the space below to draw a diagram and the lines to write you response. 36

38 Tides What are Tides? If you have ever built a sandcastle on the beach just to have it destroyed a few hours later by the ocean, you have experienced tides. There are many factors, such as topography and latitude, that contribute to how much the tides rise and fall. But what causes the tides in the first place? TIDES are the cyclical rise and fall of the level of the ocean that occur about every 12 hours. Every day there are two HIGH TIDES and two LOW TIDES. The reason for the cyclical pattern of the tides is due to the gravitational interaction between the Earth, Moon, and Sun. Gravity is a very complicated force that you need to know A LITTLE about to understand tides. Anything with mass pulls on every other objects with mass in the universe, even you! The more mass an object has the more force it can pull on other objects with. The Earth is much more massive than you are (about a quintillion or 18 zeros) and has much more force. That is why things are not always falling towards you. Mass is not the only thing that determines how much force (or gravity) an object can pull with. Distance between objects plays a big role too. The further away an object is the force it can pull with goes down exponentially. If you go 2times further from and object its force drops by 4time 2 3 (2 )and if you go 3times further from and object the force drops by 8times(2 ). 4times away force 4 drops by 16times (2 ) and so on (you do not need to know this math you just need to know that further away=a lot less force ). The moon is close to the Earth compared to other things in space. The Earth pulls on the Moon to hold it in orbit and the Moon pulls back on the Earth. Most of the Earth is rock and metal which does not react to the pull (imagine squeezing a rock). However, that water that cover 71% of the Earth s surface does react to the pull (imagine squeezing a water balloon). This causes a bulge of water on the side of the Earth closest to the Moon. As the Earth rotates some parts of the Earth are in this bulge of water and experience High tide. But, there is a also a bulge of water on the side of the Earth facing away from the Moon. A MISCONCEPTION is that this bulge is caused by the Sun, this is not the case. Since the Earth is nearly 8,000 miles thick (diameter) the water on the side opposite the moon feels less gravitational force which results in a bulge on that side too. The Sun has about 27 million times more mass than the moon but it is usually about 375 times further away than the moon. This means that the Sun only applies about 44% the force to the water that the Moon does; causing the water to rise and fall about half as much. The Sun does not cause the 2 High Tides and 2 Low Tides experienced on the Earth each day. However, it can make High Tides HIGHER or Low Tides Lower depending on how it is aligned with the Earth and the Moon. When the Sun, Earth, and Moon are in a line (syzygy) during New Moon and Full Moon High Tide is Higher and Low Tide is Lower. This is called a SPRING TIDE and happens about two time a month. When the Sun is not lined up with the Earth and Moon during First Quarter and Third Quarter Moon the High Tide is Lower and the Low Tide is Lower. This is called NEAP TIDE and happens about two times a month also. See the diagrams on the following page that help to illustrate these special tides. 37

39 Spring Tides occur two times in the lunar cycle when the Sun, Earth, and Moon are aligned; New Moon and Full Moon. In this orientation the Moon and Sun combine their gravitational pulling to make HIGHER High Tides. This pulls more water from the regions of the Earth not aligned with the Sun and the Moon and results in LOWER Low Tides. Neap Tides occur two time in the lunar cycle when the Sun, and Earth are aligned perpendicular (at a right angle) to the Earth and Moon alignment. In this orientation the Moon and Sun pull on the Earth s water at different angles making LOWER High Tides and HIGHER Low Tides. The High Tides are still on the side of the Earth facing the Moon and the direct opposite side. 38

40 Activity Sheet 39