Across
- 4. A date and time selected as a fixed reference.
- 6. A decrease in the wavelength of photons emitted by an approaching source of light.
- 7. Daily or during the day.
- 8. A localised concentration of dense material beneath the lunar surface.
- 9. A measure of how much a flattened sphere differs from a perfect sphere.
Down
- 1. A sudden, violent burning.
- 2. A small, dense, dark nebula.
- 3. Two stars revolving about each other.
- 5. An instrument for photographing the solar corona.