1. The layer of gas and dust (100's of thousands of kilometers across) 
    surrounding a comet nucleus.
3. ____-8. A NASA spacecraft launched in October 1973, in order to study 
    the space around the Earth out to about the distance of the Moon.
6. The principal component particle of atomic nuclei, other than protons.
7. The abbreviation for bundles or clouds of electrically charged gas "thrown 
    out" from near the Sun's surface and lasting from several minutes to several 
    hours.
8. The name of our planet.
10. The large collection of stars in fairly tight gravitational connection with 
      each other.
11. The abbreviation for the amount of energy needed to move an electron 
      through a one volt electrical potential.

1. The atmosphere of the Sun that can be observed out to many times the 
    size of the Sun's main surface.
2. The abbreviation for a spacecraft launched on September 25, 1997.
3. The abbreviation for part of a worldwide program of scientific space studies.
4. A bundle of light energy thought of as a particle but not having real mass.
5. Very fast moving electrically charged particles believed to come mainly 
     from our galaxy.  (2 words)
6. The very high density central part of an atom consisting of protons and 
    neutrons.
9. The abbreviation for a 3-axis coordinate system, with Earth at its center.