Astronomy Test #6 Crossword
                                                          
                                                          
                                                          
                                                          
                                                          
                                                          
                                                          
                                                          
                                                          
                                                          
                                                          
                                                          
                                                          
                                                          
                                                          
                                                          
                                                          
                                                          
                                                          
                                                          
                                                          
                                                          
                                                          
                                                          
                                                          
                                                          
                                                          
                                                          
                                                          
 
 
Down: 1) Ice could also form small particles outside the frost line. | Larger planetesimals and planets were able to form. | The gravity of these larger planets was able to draw in surrounding H and He gases. 2) Io (shown here): Active volcanoes all over | Europa: Possible subsurface ocean | Ganymede: Largest moon in solar system | Callisto: A large, cratered “ice ball”3) All four jovian planets have ring systems. | Others have ring particles that are smaller and darker than Saturn’s.5) Nearly identical in size to Earth; surface hidden by clouds | Hellish conditions due to an extreme greenhouse effect | Even hotter than Mercury: 470°C, day and night | No moon.6) Radiometric dating tells us that the oldest moon rocks are 4.4 billion years old. | The oldest meteorites are 4.55 billion years old. | Planets probably formed 4.5 billion years ago.7) Collisions between gas particles also reduce up and down motions.9) Leftover planetesimals bombarded other objects in the late stages of solar system formation.10) Elements that formed planets were made in stars and then recycled through interstellar space.12) According to the nebular theory, our solar system formed from a giant cloud of interstellar gas. (nebula = cloud)14) are very tiny compared to distances between them.15) The unusual moons of some planets may be captured planetesimals.17) Earth and Moon to scale | An oasis of life | The only surface liquid water in the solar system | A surprisingly large moon. 18) Similar to Uranus (except for axis tilt) | Many moons (including Triton)21) The spinning cloud flattens as it shrinks.22) Rings are NOT solid; they are made of countless small chunks of ice and rock, each orbiting like a tiny moon.28) Made of metal and rock; large iron core | Desolate, cratered; long, tall, steep cliffs, no moon | Very hot and very cold: 425°C (day), –170°C (night).32) Over 99.8% of solar system’s mass | 100 times bigger than Earth | Made mostly of Hydrogen and Helium gas (plasma). Across: 4) All large bodies in the solar system orbit in the same direction and in nearly the same plane. | Most also rotate in that direction. 8) Collisions between gas particles in a cloud gradually reduce random motions.10) Giant impacts might also explain the different rotation axes of some planets.11) We can see stars forming in other interstellar gas clouds, lending support to the nebular theory.13) Stars form in dark clouds of dusty gas in interstellar space. | The gas between the stars is called the interstellar medium. 16) Radiation and outflowing matter from the Sun—the solar wind— blew away the leftover gases.19) Much smaller than other planets | Icy, comet-like composition | Pluto’s moon Charon is similar in size to Pluto. 20) Much farther from Sun than inner planets | Mostly H/He; no solid surface | 300 times more massive than Earth | Many moons, rings. 23) ...then accreted into the Moon.24) Collisions between particles in the cloud caused it to flatten into a disk.25) As gravity causes the cloud to contract, it heats up. 26) There are many icy objects like Pluto on elliptical, inclined orbits beyond Neptune (Kuiper belt objects). | The largest ones are comparable in size to Earth’s Moon (Eris is bigger than Pluto). 27) Giant and gaseous like Jupiter | Spectacular rings | Many moons, including cloudy Titan | Cassini spacecraft currently studying it. 29) Inner parts of the disk are hotter than outer parts. 30) Many smaller objects collected into just a few large ones. | From planetesimals to planets! 31) Smaller than Jupiter/Saturn; much larger than Earth | Made of H/He gas and hydrogen compounds (H2O, NH3, CH4) | Extreme axis tilt | Moons and rings33) Leftovers from the accretion process. | Rocky asteroids inside frost line. | Icy comets outside frost line. 34) Terrestrial planets are rocky, relatively small, and close to the Sun. | Jovian planets are gaseous, larger, and farther from the Sun.35) Looks almost Earth-like, but don’t go without a spacesuit! | Looks almost Earth-like, but don’t go without a spacesuit! | Water flowed in the distant past; could there have been life? 2 moons, but perhaps captured small asteroids.36) Small particles of rock and metal were present inside the frost line. | Planetesmals of rock and metal built up as these particles collided. | Gravity eventually assembled these planetesimals into terrestrial planets.
 

 

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