| A | B |
|---|
| perihelion | the point in the orbit of a planet or comet at which it is nearest to the sun |
| chromospheres | a gaseous envelope surrounding a star. |
| electromagnetic | the phenomena associated with electric and magnetic fields and their interactions with each other |
| aphelion | the point in the orbit of a planet or a comet at which it is farthest from the sun. |
| insolation | exposure to the sun's rays, especially as a process of treatment. |
| ultraviolet | corresponding to light having wavelengths shorter than 4000 angstrom units |
| astronomical | extremely large; exceedingly great; enormous |
| ionization | to separate or change into ions |
| chronograph | a timepiece capable of measuring extremely brief intervals of time accurately, as a stopwatch |
| constant | invariable |
