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Across 1. A device containing such a material, especially one used to extract impurities from air or water. 4. A bright trail or streak that appears in the sky when a meteoroid is heated to incandescence by friction with the earth's atmosphere. 5. A solid body, moving in space, that is smaller than an asteroid and at least as large as a speck of dust. 8. The use of a nuclear reactor either to produce electricity to power an engine (as in a nuclear submarine) or to directly heat a propellant (as in nuclear rockets) 9. Capable of luminescence under the action of cathode rays, X rays. 10. A stony or metallic mass of matter that has fallen to the earth's surface from outer space. 13. The gaseous mass or envelope surrounding a celestial body, especially the one surrounding the earth, and retained by the celestial body's gravitational field. 15. Marked by danger; perilous 16. The amount of space occupied by a three-dimensional object or region of space, expressed in cubic units. 19. A container for liquid with a wider base gradually narrowing to the top and marked with a graded scale. 21. The act or process of rendering something harmful or unsuitable. 24. Transmitting light but causing sufficient diffusion to prevent perception of distinct images. 27. The outer or the topmost bounddary of an object. 28. The ability of an object, such as a ship or aircraft to maintain equilibrium or resume its original, upright position after displacement, as by the sea or strong winds.

Down 2. The items listed in such a report or record. 3. The formations and "looks" (as in what one looks like) of someone/something. 4. Relating to the magnetic poles of the earth. 6. A state of separation between persons or groups. 7. The circumstances or conditions that surround one;surroundings 10. A unified body of matter with no specific shape. 11. Something foretold; a prophecy 12. The scientific study of the origin, history, and structure of the earth. 14. Energy transmitted as rays, waves, in the form of particles. 17. A structure or system designed to prevent the accidental release of radioactive materials from a reactor. 18. Rocks formed by the solidification of molten magma 20. An arm used to work and/ or substitute a normal, human arm. 22. The separation of an intellectual or material whole into its constituent parts for individual study. 23. A very hard mineral composed of silica, SiO2, found world wide in many diferent types of rocks, including sandstone and granite. 25. Scientific instrument consisting of displays and an input device that an operator can use to monitor and control a system (especially a computer system) 26. The mass per unit volume of a substance under specified conditions of pressure and temperature.