Earth Science Unit 6: Astronomy Period: Date: Elliptical Orbits

Transcription

1 Earth Science Name: Unit 6: Astronomy Period: Date: Lab # 5 Elliptical Orbits Objective: To compare the shape of the earth s orbit (eccentricity) with the orbits of and with a circle. other planets Focus Focus d L distance between foci Length of major axis Procedure: Materials: Loop of String Board 2 Push-pins White Drawing Paper Colored Pencils 1. On a plain sheet of white paper, lightly draw a straight line down the middle of the paper (lengthwise). 2. Near the center of this line, draw two (2) dots 3 cm apart. 3. Place the paper on the board and put a thumbtack in each dot (focus) Loop the string around the thumbtacks and draw the ellipse by placing your pencil inside the loop as shown below. 6. Label this ellipse #1 7. Draw a SUN around one (1) of the dots. 8. Measure the distance between the foci (thumbtacks) and record this on your report sheet under d. 9. Measure the length of the major axis L and record this on the report sheet. 10. Remove only one (1) of the tacks and slide it away from the other by an additional 2.0 cm and using a different color pencil, draw a second ellipse. Label this ellipse #2 and measure and record d and L. 11. Place a dot in the exact center of the first (original) two (2) foci. Using only one (1) thumbtack, loop the string around the tack and draw a circle. Elliptical Orbits Lab 9/5/2013 1

2 12. Write the formula for eccentricity (E) found in your notes on page Calculate the eccentricity for each of the figures you drew. Round all answers to the nearest You must show all your work!!! Ellipse #1 Ellipse #2 Circle Questions and Conclusions: 1. What happens to the shape of an ellipse as its eccentricity approaches 1.0? 2. What happens to the shape of an ellipse as its eccentricity approaches zero? 3. What is the minimum eccentricity that an ellipse can have? 4. What is the name of the geometric figure which has the minimum eccentricity? 5. Which of the 2 ellipses you drew, not including the circle, was the most eccentric (OVAL)? 6. Which of the 2 ellipses you drew, not including the circle, was the least eccentric (CIRCLE)? 7. How does the numerical value of E change as the shape of the ellipse approaches a straight line? [Answer in complete sentences] 8. Where is the sun located on a diagram of Earth s orbit? [Answer in complete sentences] Elliptical Orbits Lab 9/5/2013 2

3 9. The following is a list of eccentricities for the planets of our solar system: Planet Eccentricity Planet Eccentricity Mercury Jupiter Venus Saturn Earth Uranus Mars Neptune Which planet has the most circular orbit? 11. Which planet has the most eccentric orbit? 12. Would the orbit of Earth look more eccentric or circular when viewed from space? 13. The diagram to the right shows a planet's orbit around the Sun. At which location is the planet's orbital velocity greatest? 14. The actual shape of the Earth's orbit around the Sun is best described as A) a slightly eccentric ellipse B) an oblate spheroid C) a perfect circle D) a very eccentric ellipse 15. Planet A has a greater mean distance from the Sun than planet B. On the basis of this fact, which further comparison can be correctly made between the two planets? A) Planet A's day is longer. B) Planet A's revolution period is longer. C) Planet A is larger. D) Planet A's speed of rotation is greater. 16. Other than Jupiter, identify one Jovian (GAS GIANT) planet in our solar system. 17. Obtain a calendar for 2013 and count the number of days between the Spring (Vernal) Equinox and the Fall (Autumnal) Equinox. Now count the number of days from the Fall Equinox to the Spring Equinox. Are they the same? Explain. Elliptical Orbits Lab 9/5/2013 3

4 18. Below is a diagram which shows the Earth s orbit and the partial orbit of a comet. Earth s orbit Orbit of Comet sun Not drawn to scale Compared with the Earth s orbit would you describe the comet s orbit as being more or less eccentric than that of the Earth? Part B: Period of Revolution Directions: Answer the following questions based on your knowledge of orbital velocities and Kepler s Second Law. Base your answers to questions 1 and 2 on the diagram below, which shows Earth s orbit and the orbit of a comet within our solar system. 1. Explain how this comet s orbit illustrates the heliocentric model of our solar system. 2. Explain why the time required for one revolution of the comet is more than the time required for one revolution of Earth. Elliptical Orbits Lab 9/5/2013 4

5 Base your answers to questions 3 through 5 on the diagram below, which represents a model of Earth s orbit. Earth is closest to the Sun at one point in its orbit (perihelion) and farthest from the Sun at another point in its orbit (aphelion). The Sun and point B represent the foci of this orbit. 3. Explain why Earth s orbit is considered to be elliptical. 4. Describe the change that takes place in the gravitational attraction between Earth and the Sun as Earth moves from perihelion to aphelion and back to perihelion during one year. 5. Describe how the shape of Earth s orbit would differ if the Sun and focus B were farther apart. Elliptical Orbits Lab 9/5/2013 5