1. A region around a magnetic planet formed by the motion of the solar 
   wind ramming into that magnetic field.
2. The ability to do work.
4. The boundary of number one across.
5. A very hot gas ball composed mostly of the element hydrogen.
6. A series of magnetic disturbances on a planet causing auroras (in 
   Earth's case) at lower latitudes.
9. An instrument that measures the strength of the magnetic field.
11. The abbreviation for the speed of light.
13. The elongated region of a planet's magnetosphere extending away 
    from the sun.
16. A spacecraft launched on September 25, 1997 to measure the composition 
    of the solar wind.
17. A spacecraft built by the European Space Community and launched in 
    December 1995.
18. The smallest particle into which an element can be broken.
20. A spacecraft that orbits another body; also a moon.
21. The process in which oppositely directed lines of force merge together 
    and tend to cancel each other out. (2 words)
27. The layer of gas and dust (100's of thousands of kilometers across)
    surrounding a comet nucleus.
28. The abbreviation for the amount of energy needed to move an electron 
    through a one volt electrical potential.
29. The abbreviation for a 3-axis coordinate system, with Earth at its center.
31. The study of the average motion, density, temperature, etc., of charged 
    particles that work together like a fluid which remains electrically 
    neutral as a whole.

1. The planet closest to the Sun. 
3. A Japanese spacecraft, with significant U.S. and U.K. contributions, 
   launched in 1991 that performs dynamic x-ray imaging of the Sun.
4. The natural satellites orbiting around planets.
5. With 19 down, a series of disturbances on a planet causing auroras 
   (in Earth's case) at lower latitudes.
7. The abbreviation for a unit of electrical current equivalent to about 
   6 X 1018 electrons per second.
8. ______ of light, which is 186,284 miles per second or 299,796 kilometer 
   per second.
10. The large collection of stars in fairly tight gravitational connection 
    with each other.
11. A process by which an atom or ion is raised to a higher energy state.
13. The fourth planet from the Sun.
14. A small, positively charged particle; one of the main particles of 
    the nucleus of an atom, which can also exist outside of a nucleus.
15. The process of emitting visible light after a gas has absorbed 
    ultraviolet light (or other short wavelength light).
19. With 5 down, a series of disturbances on a planet causing auroras 
    (in Earth's case) at lower latitudes.
22. The third planet from our Sun.
23. A fragile body of ice and dust in orbit around the Sun.
24. The regions in the magnetosphere of a planet where the magnetic field 
    lines of force have a geometrical shape like a funnel.
25. Space where there is very little or no matter.
26. The nearest star to our planet.
29. The abbreviation for a coordinate system useful for scientists who 
    study the Earth's magnetosphere and which depends on the direction 
    of the Earth's magnetic dipole.
30. The abbreviation for the mass of a thousand grams.