Astronomy Test #6 Chapter 10 Crossword
                                                         
                                                         
                                                         
                                                         
                                                         
                                                         
                                                         
                                                         
                                                         
                                                         
                                                         
                                                         
                                                         
                                                         
                                                         
                                                         
                                                         
                                                         
                                                         
                                                         
                                                         
                                                         
                                                         
                                                         
                                                         
                                                         
                                                         
                                                         
 
 
Down: 2) Nebular theory predicts that massive Jupiter-like planets should not form inside the frost line (at << 5 AU). | The discovery of “hot Jupiters” has forced a reexamination of nebular theory. | “Planetary migration” or gravitational encounters may explain “hot Jupiters.”3) Kepler (launched in 2008) have monitored about 100,000 stars for transit events for several years. | Later: Planned orbiting interferometers will obtain spectra and crude images of Earth-size planets.5) We cannot measure an exact mass for a planet without knowing the tilt of its orbit, because Doppler shift tells us only the velocity toward or away from us. | Doppler data give us lower limits on masses.7) There seem to be a much greater variety of planet types than we find in our solar system. | This includes gas giants with very different densities and water worlds.8) We can detect planets by measuring the change in a star’s position in the sky. | However, these tiny motions are very difficult to measure (~0.001 arcsecond).14) Measurements of stellar properties revealing the effects of orbiting planets Across: 1)  Some extrasolar planets have highly elliptical orbits. | Planets show huge diversity in size and density. | Some massive planets, called hot Jupiters, orbit very close to their stars.4) Doppler shifts of Sun-like star 51 Pegasi indirectly reveal planet with 4-day orbital period. | Short period means small orbital distance | First extrasolar planet to be discovered (1995) 6) Close gravitational encounters between two massive planets can eject one planet while flinging the other into a highly elliptical orbit. | Multiple close encounters with smaller planetesimals can also cause inward migration.9) Most of the detected planets have orbits smaller than Jupiter's. | Planets at greater distances are harder to detect with the current techniques.10) Measuring a star’s Doppler shift can tell us its motion toward and away from us. | Current techniques can measure motions as small as 1 m/s (walking speed!).11) Orbital period, distance, and shape | Planet mass, size, and density | Atmospheric properties 12) Special techniques for concentrating or eliminating bright starlight are enabling the direct detection of planets.13) A transit is when a planet crosses in front of a star (edge-on). | The resulting eclipse reduces the star’s apparent brightness and tells us the planet’s radius. | When there is no orbital tilt, an accurate measurement of planet mass can be obtained.15) Measurements of stellar properties revealing the effects of orbiting planets 16) The Sun and Jupiter orbit around their common center of mass. | The Sun therefore wobbles around that center of mass with the same period as Jupiter.17) Sun’s motion around solar system’s center of mass depends on tugs from all the planets. | Astronomers who measured this motion around other stars could determine masses and orbits of all the planets. 18)  Observations of extrasolar planets have shown that the nebular theory was incomplete. | Effects like planet migration and gravitational encounters might be more important than previously thought. 19) A young planet’s motion can create waves in a planet- forming disk. | Models show that matter in these waves can tug on a planet, causing its orbit to migrate inward.20) A Sun-like star is about a billion times brighter than the light reflected from its planets.21) Planets are close to their stars, relative to the distance from us to the star. (This is like being in San Francisco and trying to see a pinhead 15 meters from a grapefruit in Washington, D.C.)22) More than one in ten stars examined so far have turned out to have planets. | The others may still have smaller (Earth- sized) planets that are hard to be detected using current techniques.
 

 

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