Dynamics of Celestial Orbits: Barycenters and Planetary Systems

Barycenter Environmental Science Name: _________________________________________ Period: ________ Date: _______________ Essential Question: How is the barycenter affected by the mass of the object? Instructions: Read the selection and answer the questions. Our solar system consists of the Sun and the many millions of celestial bodies, including large planets and microscopic dust particles, which orbit around it. As a unit, the solar system has a center of mass, its balancing point. At this point, the system would balance like a spinning plate atop a circus performer's balancing stick. This point, called the barycenter, is the exact point about which all the bodies in the solar system orbit. Since the Sun is vastly larger and heavier than all the other bodies combined, the solar system's barycenter is very close to the Sun—but not at the Sun's center. Thus, while all the other solar system bodies seem to orbit the Sun, they, including the Sun, are actually orbiting a point in space just beyond the Sun's outer layer. Did You Know that the Moon Doesn’t Orbit the Earth? Orbit means to move in a curved path around another something. In astronomy, celestial bodies are generally described as moving or orbiting some other celestial body. For example, the Moon is said to orbit or revolve around the Earth. The Earth doesn’t stays in position as the Moon circles it. Just like the planets orbiting the Sun, moons orbiting planets also comprise a system with a center of mass. For the Earth-Moon system, the barycenter is located 1,710 km below the surface of the Earth. This is because the Earth is far more massive than the Moon and it is this common center of mass around which the Earth and the Moon seem to go around. The International Astronomical Union (IAU) does not consider the Earth-Moon system as a double-planet system, since the center of mass does not lie between them but rather within the Earth. A Method to Locate Planets Astronomers are using the concept of the barycenter to locate new planets around stars outside our Solar System. The way this is done is that since a planet and its star orbit a common center and due to the star being more massive, the center of mass is located within the star itself. This actually causes the star to "wobble" in its path and it is this tell-tale signature of wobbling of stars that tells astronomers that a planet is causing the effect. Many extrasolar planets have been located around various stars in our own galaxy making the barycentric approach a useful and practical means of planet hunting. Did you read the selection on the first page? If YES! You can answer these questions. 1. What is our solar system made of? Our solar system is made of the Sun and many millions of celestial bodies, including large planets and microscopic _____________________________________________________________________________________ dust particles, which orbit around it _____________________________________________________________________________________ _____________________________________________________________________________________ 2. What is the barycenter? The barycenter is the center of mass of a system, around which all the bodies in the system orbit _____________________________________________________________________________________ _____________________________________________________________________________________ ____________________________________________________________________________________ 3. Where is the barycenter of the solar system? The barycenter of the solar system is very close to the Sun, but not at the Sun's center. _____________________________________________________________________________________ _____________________________________________________________________________________ 4. Why is the barycenter of the solar system either inside or very close to the Sun? The barycenter of the solar system is either inside or very close to the Sun because the Sun is vastly larger and _____________________________________________________________________________________ heavier than all the other bodies combined. _____________________________________________________________________________________ _____________________________________________________________________________________ 5. Does the moon orbit around earth? Explain. No, the Moon does not orbit around the Earth. Instead, both the Earth and the Moon orbit around their common _____________________________________________________________________________________ center of mass, which is located within the Earth. _____________________________________________________________________________________ _____________________________________________________________________________________ 6. Does the earth stay in position as the moon revolves around it? Read the whole selection first and then explain your answer. No, the Earth does not stay in a fixed position as the Moon revolves around it. Both the Earth and the Moon orbit _____________________________________________________________________________________ around their common center of mass, causing the Earth to also move. _____________________________________________________________________________________ _____________________________________________________________________________________ 7. Where is the barycenter of the earth and the moon? The barycenter of the Earth and the Moon is located 1,710 km below the surface of the Earth. _____________________________________________________________________________________ _____________________________________________________________________________________ ____________________________________________________________________________________ 8. Why is the barycenter of the earth and the moon found below the surface of earth? ( 1,710 km or 1062.54 miles below the surface of earth) The barycenter of the Earth and the Moon is found below the surface of the Earth because the Earth is far more _____________________________________________________________________________________ massive than the Moon, so the center of mass lies closer to the Earth. ____________________________________________________________________________________ 9. What does IAU stands for? IAU stands for the International Astronomical Union. _____________________________________________________________________________________ ____________________________________________________________________________________ 10. Why is the Earth-Moon System not considered as double planet system? The Earth-Moon system is not considered a double-planet system because the center of mass does not lie _____________________________________________________________________________________ between them but rather within the Earth _____________________________________________________________________________________ _____________________________________________________________________________________ 11. How do astronomers use the concept of barycenter to locate new planets around stars outside our Solar system? Astronomers use the concept of the barycenter to locate new planets around stars outside our solar system by _____________________________________________________________________________________ observing the "wobble" of stars caused by the gravitational pull of planets orbiting around them. _____________________________________________________________________________________ 12. What do wobbling stars tell astronomers? Wobbling stars tell astronomers that a planet is causing the effect, indicating the presence of extrasolar planets _____________________________________________________________________________________ around various stars in our galaxy. _____________________________________________________________________________________ _____________________________________________________________________________________