Across
- 4. Theory Theory that explains planetary and stellar magnetic fields in terms of rotating, conducting material flowing in an object’s interior.
- 7. Layer of gas confined close to a planet’s surface by the force of gravity.
- 9. A zone of charged particles trapped by a planet’s magnetic field, lying above the atmosphere.
- 10. Force The variation in one body’s gravitational force from place to place across another body (for example, the variation of the Moon’s gravity across Earth).
- 12. Layer Layer of Earth’s atmosphere at an altitude of 20 to 50 km where incoming ultraviolet solar radiation is absorbed by oxygen, ozone, and nitrogen in the atmosphere.
- 15. Cycle Process by which surface rock on Earth is continuously redistributed and transformed from one type into another.
- 16. Layer of Earth that contains the liquid oceans and accounts for roughly 70 percent of Earth’s total surface area.
- 18. Allen Belt One of at least two doughnut-shaped regions of magnetically trapped, charged particles high above Earth’s atmosphere.
- 19. Rising and falling motion of terrestrial bodies of water, exhibiting daily, monthly, and yearly cycles. Ocean tides on Earth are caused by the competing gravitational pull of the Moon and Sun on different parts of Earth.
- 21. The central region of Earth, surrounded by the mantle. The central region of any planet or star.
- 22. The portion of Earth’s atmosphere from the surface to about 12 km.
- 23. The amount of time it takes for half of the initial amount of a radioactive substance to decay into something else.
- 25. Core The central part of Earth’s core, thought to be solid, and composed mainly of nickel and iron.
- 26. The portion of Earth’s atmosphere lying above the troposphere, extending up to an altitude of 40 to 50 km.
- 29. Core The outermost part of Earth’s core, thought to be liquid and composed mainly of nickel and iron.
- 30. Wave A wave that travels outward from the site of an earthquake through Earth.
Down
- 1. Layer of Earth just interior to the crust.
- 2. Churning motion resulting from the constant upwelling of warm fluid and the concurrent downward flow of cooler material to take its place.
- 3. Region of Earth’s atmosphere lying between the stratosphere and the ionosphere, 50 to 80 km above Earth’s surface.
- 4. Variation in the density and composition of a body, such as Earth, with low-density material on the surface and higher-density material in the core.
- 5. Effect The partial trapping of solar radiation by a planetary atmosphere, similar to the trapping of heat in a greenhouse.
- 6. Layer in Earth’s atmosphere above about 80 km where the atmosphere is significantly ionized and conducts electricity.
- 8. Bulge Elongation of Earth caused by the difference between the gravitational force on the side nearest the Moon and the force on the side farthest from the Moon. The long axis of the tidal bulge points toward the Moon. More generally, the deformation of any body produced by the tidal effect of a nearby gravitating object.
- 9. Ridge Place where two plates are moving apart, allowing fresh magma to well up.
- 11. Layer of Earth’s interior, just below the lithosphere, over which the surface plates slide.
- 13. The release of energy by rare, heavy elements when their nuclei decay into lighter nuclei.
- 14. Layer of Earth that contains the solid continents and the seafloor.
- 17. Zone Place where two plates meet and one slides under the other.
- 20. Gas Gas (such as carbon dioxide or water vapor) that efficiently absorbs infrared radiation.
- 24. Earth’s crust and a small portion of the upper mantle that make up Earth’s plates. This layer of Earth undergoes tectonic activity.
- 27. Event that occurs when atmospheric molecules are excited by incoming charged particles from the solar wind, then emit energy as they fall back to their ground states. Aurorae generally occur at high latitudes, near the north and south magnetic poles.
- 28. Tectonics The motions of regions of Earth’s lithosphere, which drift with respect to one another. Also known as continental drift.