Pre and post-visit activities - Navigating by the stars

Transcription

1 Pre and post-visit activities - Navigating by the stars Vocabulary List Adult Education at Scienceworks Pre-visit Activity 1: What is longitude and latitude? Activity 2: Using the Southern Cross to find South Activity 3: Measuring your latitude using hand-spans Activity 4: Measuring your latitude using a quadrant Post-visit Activity 5: Space spin-offs (Certificate I & II) Activity 6: Where on Earth are you? (Certificate II) These activities are designed to familiarise Certificate I and II students with the concepts and vocabulary they will encounter when they visit Scienceworks to see the Guiding Lights planetarium show, and to reinforce and extend their knowledge afterwards. You may need to modify or extend some of the ideas presented to best suit the needs of your students or student groups. Students should become familiar with the following words and their meanings, particularly those used in the planetarium show synopsis and on-site activities, before they visit Scienceworks. Navigating by the stars

2 Vocabulary list - Navigating by the stars Words Activities Words Activities Adult Education at Scienceworks Navigating by the stars accurate, accuracy, accurately adapted celestial charted complementary (techniques) connect, connection demonstrates (to) determine device earthbound effect, effected instruments invent, invention launch objects navigate, navigating, navigation orbit, orbiting to orient (themselves) predict relatively recent times satellites solution sophisticated splendour straightforward unprecedented utilized (utilised) chronometer cross-staff GPS (Global Positioning System) kamal latitude longitude quadrant sextant Show Synopsis Scientific terminology coordinate (terrestrial coordinate system) devised horizontal, horizontally international convention parallel prime meridian reference lines sphere, spherical terrestrial / celestial vertical, vertically altitude arc axis constellation hemisphere intersection right angle Activity 1 Activity 2 angular distance Activity 3 brass heavenly body locate secure tabulated value accurate chronometer illustrating influenced or affected instruments invent, invention latitude navigational system revolution, revolutionised spin-off Activity 4 On-site & Postvisit

3 Activity 1: What is longitude and latitude? Background information Due to the enthusiasm of our great explorers about 500 years ago, the demand for accurate maps and charts increased. It was only about a century ago that an international convention devised a terrestrial coordinate system using the lines of longitude and latitude. There are two main (imaginary) reference lines that divide the Earth vertically and horizontally and are marked 0 degrees. The equator is one of them and divides the Earth into two equal halves. The equator marks 0 degrees latitude and the lines of latitude run parallel to one another, measuring the distance, north or south from the equator. The North Pole lies at a latitude of 90 degrees North and the South Pole lies at a latitude of 90 degrees South. Recognised latitude lines: The Tropic of Cancer The Tropic of Capricorn The Arctic Circle Antarctic Circle 23.5 degrees N 23.5 degrees S 66.5 degrees N 66.5 degrees S The Tropic of Cancer and the Tropic of Capricorn mark the furthest points north and south of the equator where the Sun's rays fall vertically. The Arctic Circle and the Antarctic Circle mark the furthest points north or south of the equator where the Sun appears above the horizon each day of the year. Inside the Antarctic and Arctic Circles, the Sun does not appear above the horizon for the winter months and never drops below the horizon during the summer months. The other 0 degree (imaginary) reference line is the line that runs vertically through the North Pole, the South Pole and Greenwich in England. This line is called the prime meridian. The prime meridian was chosen to go through Greenwich because Greenwich Observatory played a major part in determining longitude at sea. Imaginary lines that run from the North Pole to the South Pole divide the Earth into sections. These imaginary lines are called lines of longitude or meridians and are measured east or west of the Prime Meridian. 3

4 Using this coordinate system, one can locate any place on Earth with accuracy. Some examples: The latitude and longitude for: a) Melbourne 38 degrees S, 145 degrees E b) Los Angeles (USA) 34 degrees N, degrees W c) Kenya 1 degree N, 38 degrees E d) Paris 48 degrees N, 2.20 degrees E What you need Spherical object eg. foam ball, blown up balloon Texta Earth globe String Sticky-tape What to do Use an Earth globe to help you do the following activity. 1 Mark in the North and South Pole on your spherical object. 2 Mark and label the equator half way around your spherical object as best as you can either using a texta or sticking a piece of string horizontally around the diameter. 3 Add lines of latitude 30 degrees S, 30 degrees N, 60 degrees S and 60 degrees N. (The lines of latitude are measured from the equator. Use the diagram on page 9 as a reference. ) 4 Mark in and label The Tropic of Cancer (23.5 degrees N) and the Tropic of Capricorn (23.5 degrees S). 5 Mark in and label the Arctic Circle (66.5 degrees N) and the Antarctic Circle (66.5 degrees S). 6 Mark and label the prime meridian that passes vertically through the North and South Pole. (The lines of longitude are measured from the prime meridian, which passes through Greenwich, England.) 7 Mark in lines of longitude 45 degrees E, 90 degrees E and 135 degrees E, 45 degrees W, 90 degrees W, 135 degrees W. 8 Find out the longitude and latitude of three different places you would like to visit and mark the (approximate) positions using the scale on your model. 4

5 Activity 2: Using the Southern Cross to find South Background information One of the things that that makes finding stars and constellations difficult is that the stars seem to move slowly across the sky during the night, rising in the East and setting in the West, just like the Sun during the day. From Southern Australia, if you watched the stars for a few hours they would move like this (if you are facing South): East SCP West Horizen Some stars travel in a large arc across the sky, then disappear below the horizon. Other stars never 'set' below the horizon but trace a circle in the sky. At the centre of these circles is a point called the South Celestial Pole. This part of the sky is directly above the South Pole of the Earth. That is, if you stood at the South Pole, the South Celestial Pole would be directly overhead. During summer at the South Pole the Sun circles the sky and never sets meaning it is daytime continuously. During winter the Sun never rises and it is constantly night. In the Northern Hemisphere, a star called Polaris or the Pole Star marks the North Celestial Pole. There is no star near the South Celestial Pole, so instead southerners must use the Southern Cross to find South. Once you are familiar with finding the Southern Cross, it can be used to find the direction of south, at any time of night, at any time of year because the Southern Cross never sets in our night sky, when viewed from the Southern part of Australia. 5

6 What to do To find South: 1 Find the Southern Cross. 2 Draw an imaginary line through the long axis of the Southern Cross beginning with the star that marks the top of the cross (note: during summer the Southern Cross is low in the sky and therefore upside-down). 3 Extend the line four and a half times the length of the cross. 4 This will bring you to the point in the sky called the South Celestial Pole. 5 From this point, drop a line vertically down to the horizon. This gives you the direction of true South. (Compasses find magnetic north/south, not True North/South, so a compass will measure magnetic south to be 11 degrees west of True South in Victoria.) Alternative method of finding South: This method involves using the two bright Pointer stars - Alpha Centauri and Beta- Centauri - that lie near the Southern Cross in the constellation of Centaurus. After step 2 above, draw a perpendicular bisector between the two Pointers, that is, a line starting at the mid-point between the two Pointers and coming out at right angles. This line should cross the line you drew in step 2. The intersection of these two lines is close to the South Celestial Pole. SCP S SCP S 6

7 Activity 3: Measuring your latitude using hand-spans Background information Latitude is the angular distance of a location north or south of the equator. The latitude for Melbourne is about 38 degrees. The latitude of a location can be determined using the stars, by measuring a height of a Celestial Pole above the horizon. In the Southern Hemisphere we use the South Celestial Pole. If you are unfamiliar with using the Southern Cross to find the South Celestial Pole, refer to Activity 4 in this education kit. In the Northern Hemisphere, the North Celestial Pole is used to measure latitude. The North Celestial Pole is marked by the star Polaris. The distance measured from the horizon to Polaris in degrees is equal to the latitude of a location in the Northern Hemisphere. You can make approximate angular measurements using your fingers and hands at arms length which then allows you to find the positions of particular stars and constellations, and even measure your latitude. Measuring large angles: Outstretch one arm so that it is parallel with the horizon. This arm will act as your baseline. Hold your other arm straight up beside your head. Both arms are now at right angles. A 45 degree angle can be made by moving your upright arm to half the 90 degree angle. With practice you can even divide the 90 degree angle into thirds and measure a 30 degree angle. Measuring smaller angles: One finger width at arms length covers about two degrees of sky and can be used to measure small distances between stars. Half a hand-span (at arms length) is the distance across the knuckles of one hand. It covers about 10 degrees across the sky. A whole hand-span is an outstretched open hand. It measures 20 degrees across the sky. Australian latitudes Melbourne Sydney Brisbane Adelaide Perth Hobart Darwin Canberra ~ 38 degrees ~ 34 degrees ~ 28 degrees ~ 35 degrees ~ 32 degrees ~ 43 degrees ~ 12 degrees ~ 35 degrees 7

8 What you need Clear night What to do 1 On a clear night, find the Southern Cross and use it to find the approximate position of the South Celestial Pole. (Refer back to Activity 2) 2 Measure your latitude by measuring the distance between the horizon and the South Celestial Pole using hand-spans and finger width measurements as accurately as you can. 3 Discuss how accurate the measurements are. Compare measurements with other students. Who had the closest value to the tabulated value? Find out why. Question 1 If you were standing at the a) South Pole what would your latitude be? b) North Pole c) equator 8

9 Activity 4: Measuring your latitude using a quadrant Background information A quadrant is a very simple instrument that was used to determine the altitude of a heavenly body. It was made out of wood or brass and came into widespread use around It takes its name from its shape which is a quarter of a circle. A cord with a small weight or plumb bob made of lead or brass hangs down from the right angle which establishes a vertical line of reference. The quadrant is held at an angle so that the altitude of a heavenly body could be found from a simple reading on the scale. The following activity shows you how to make and use a simple quadrant. What you need A4 cardboard Glue Scissors Worksheet Measuring your latitude using a Quadrant String 25cm Sticky tape Weight or washer Straw cut in half What to do 1 Stick the worksheet onto the piece of cardboard. 2 Cut around the dark outline. 3 Poke a hole through the point marked X. 4 Insert the string from the graduated side of the quadrant and stick the string behind the quadrant using sticky-tape so that it is secure. 5 Tie the small weight onto the other end of the string. 6 Stick a straw with glue or sticky tape so that it lines up with the dotted line. How to use the quadrant to measure your latitude: Note: It is advisable to practise using the quadrant to measure the altitude of various objects (eg. top of a building or church) during the daytime before using it to measure latitude. 7 Go outside on a clear night and find the Southern Cross. Use the Southern Cross to locate the South Celestial Pole as accurately as possible. (Refer to Activity 2) 8 Start with holding the quadrant so that the weight hangs down along the zero line on the scale and the straw lines up with the horizon at eye level. 9 Then look through the straw and locate the South Celestial Pole. Since the quadrant is no longer horizontal, the string will move. 10 Hold the string in place against the quadrant. 11 Read the number of degrees between 0 degrees and 90 degrees. You now have an approximate measurement of your latitude. Repeat steps 8-11 three or four times so that an average value can be calculated. Compare the result to the tabulated value for your area. Optional 12 Use your quadrant and star map to check the altitude of given stars on a clear night. 9

10 front 70 x0 Measuring your latitude using a quadrant Worksheet x0 glue straw along dotted line glue straw along dotted line front 10

11 Activity 5: Space spin-offs Certificate I and II Background information A space spin-off is an invention originally developed for the space program but then was adapted to useful things we use every day. What you need Research facilities What to do Research another two space spin-offs that you make use of in your life and answer the following questions for each one: Questions 1. What was the object originally invented for? 2. What is the use of this object in every day life? 3. How did this object go from being a space related object to an object people use every day? 4. Get into groups of four and share your information with the group. 5. Make a list of space spin -offs researched by your group members. 6. Produce a poster illustrating all the spin-offs in your list and display in the classroom. 11

12 Activity 6: Where on Earth are you? Certificate II Background information A space spin-off is an invention originally developed for the space program but then was adapted to useful things we use every day. An example of a space spin-off is a ball point pen. It was originally invented for people in space so they could write up-side-down. What you need Research facilities What to do 1. Research the GPS (Global Positioning System). Find out how this system revolutionised navigation 2. How has this invention influenced or affected your life directly or indirectly? 3. Research the history of navigation and draw a simple time-line that outlines the major developments in the history of navigation. 4. Research the reasons for and against spending so much money on space research and exploration and then prepare a debate. 12