related to the song:
'Dance of the Planets'
Using real data from two new planetary systems discovered around neighboring stars in 1995 and 1996, students will compare the orbit paths that each travels as they revolve around a central star. They will compare and contrast their results to the data obtained from our own solar system, analyze each orbit path, and compare their size, shape, and eccentricity.
In your journal, draw your prediction of how our solar system is arranged as the planets orbit the Sun. Be sure to include the number of planets and their names, the order in which they are arranged, and how large you think the distances between the planets are.
You will be working with other NASA scientists to gather data pertaining to the distances each planet is from the Sun. Your team will consist of four members. Each individual in the group will have a specific responsibility based on the following jobs.
How did the solar system form? Do other stars in our neighborhood of the galaxy have planets orbiting them? In order to understand these fundamental questions (Where did we come from? Are we alone in the Universe?), we must learn everything we can about our solar system. One area we can study is the organization of the planets that make up our solar system.
The distances between planets and the planets' distances from the Sun vary considerably throughout the solar system. In this activity, you'll make a scale model of the solar system and use it to discover how the planets are arranged in the solar system.
Paper (3 in. x 36 in.)
Solar System Data Table
The following steps (procedures) are to be followed in conducting this activity.
Remember when you read to perform a task:
Take a close look at the portrait you have drawn. The four planets closest to the Sun (Mercury, Venus, Earth, Mars) are known as the inner (or terrestrial) planets. The five planets furthest from the Sun are known as the outer planets (Jupiter, Saturn, Uranus, Neptune, and Pluto). Four of these (Jupiter, Saturn, Uranus, Neptune) are gas giants. Pluto is smaller than many of Jupiter's and Saturn's satellites, and the Earth's own Moon).
Question 1a: Explain how a scaled distance is determined. Question 1b: On your model, observe the four planets closest to the Sun, then the five farthest away. How do the distances from one inner planet to the others compare to the distances from one outer planet to the others? Question 1c: The force of gravity is stronger at shorter distances. As the gravitational force increases, a planet's orbital speed increases. Knowing this, which planet's period of revolution is shortest? Explain. Question 1d: The surface of each planet receives its heat energy from the Sun. Therefore, would you predict that the surface temperature of Pluto would be greater or less than the surface temperature of Mars? Why? Question 1e: What force keeps the Earth and other planets in their orbital paths as they revolve around the Sun? Explain.
Question 1f: In addition to scale distances, what other information would you need to construct an exact scale model of the solar system? Question 1g: Refer back to the drawing you made during the engagement activity. Describe how your predicted distances between the planets and the planets' distances from the Sun differ from the scaled model you made. How would you have to change your first model in order for your drawing to represent a more accurate picture of the scaled model of the solar system?
You and your team of NASA scientists have been asked to investigate two new planetary systems discovered around neighboring stars. These systems were actually discovered in 1995 and 1996 from real data. You are asked to investigate the orbit that each travels as they revolve around the central star. Compare your results to the data obtained from our own solar system. Analyze each orbit path and compare their size (distance from the central star), and shape (eccentricity) to complete the following activities.
In all cases, use the information found in the data chart to scale the distances appropriately. Since the Sun (or star) is always at one focus of the elliptical orbit of planets around it, make sure one pin stays at the center of each poster board. Label each ellipse as you draw it. Use different colored pencils to represent each ellipse and construct a color key. The scale for each planetary system is 1 AU = 2.0 cm. Record this information on each of your solar system orbit maps.
|Earth||0.1 cm||5.9 cm|
|Jupiter||1.4 cm||30.4 cm|
|16 Cygni||3.2 cm||8.2 cm|
|Lalande A||0.2 cm||14.8 cm|
|Lalande B||0.2 cm||58.2 cm|
Question 2a: Compare and contrast the shape and size of Earth's orbit to that of Jupiter's.
Add the following information to the data chart below by measuring the length of the major axis (L) of each planetary orbit in cm.
|Constructed Ellipse||Pin Separation
d in cm
L in cm
Length in AU
Question 2b: What is the eccentricity of each of the constructed ellipses? Eccentricity can be calculated by dividing d/L = e. Add the eccentricities to the data chart above. Question 2c: Calculate the major axis for each orbit in Astronomical Units (AU). The distance in AU can be formulated by dividing distance in centimeters by 2.0 cm to convert cm to AU.
Question 2d: Compare the 16 Cygni planetary system to the planets in our own solar system. Using the Solar System data table, find the solar system planet whose distance from the Sun (in AU) is closest to the distance of 16 Cygni's planet from its star. How does the eccentricity of 16 Cygni's planet compare to Earth's orbital eccentricity? Question 2e: Compare the distances of Lalande A and Lalande B to their star with the distances within our solar system. Do you see any similarities between the planetary distances in the Lalande system and those in the Solar System? Which planet in our solar system has an eccentricity closest to that of Lalande A? Question 2f: A circle is just a special case of an ellipse with an eccentricity of 0.0. In this case, the foci are on top of each other; the distance between them is zero and they reside at the center of the circle. Which of the planets outside our solar system orbits on an ellipse that is closest to circular? Question 2g: What do you think the surface temperatures would be like on these planets? Assume their stars are about as energetic as our Sun.
How can the information obtained from the activities (scaled portrait, mapping orbits, calculating eccentricity, and determining distances of planets from their stars) help scientists compare new planetary systems to that of our own solar system? Scientists think life may evolve on planets with similar distances and eccentricities as Earth's orbit. Discuss this possibility in this article.
Before you write:
Think about how the information collected can be compared to what we already know about our own solar system.
Marcy, Geoffrey W. and R. Paul Butler. "Giant Planets Orbiting Faraway Stars". Scientific American: Magnificent Cosmos: 9(1):10-15. Spring 1998.
Naeye, Robert. "The Strange New Planetary Zoo". Astronomy 25(4):42-49. April 1997.
Naeye, Robert. "2 New Solar Systems". Astronomy 24(4):50-55. April 1996.
MacRobert, Alan M. and Joshua Roth. "The Planet of 51 Pegasi". Sky & Telescope 91(1):38-40. January 1996.