Chapter 27

3. The Moon's shadow falls on the Earth.
4. Valley-like structures on the Moon's maria.
8. Trails of ejecta extending from a lunar impact crater.
9. Light is bent, or refracted, as it passes through an objective lens, and an eyepiece lens then magnifies the resulting image.
13. A curved primary mirror collects light and reflects it to a secondary mirror, which then directs the light to an eyepiece or camera.
15. The Moon's orbital and rotational periods are equal, so the same side always faces Earth.
18. The point where the Moon is farthest from Earth in its orbit.
19. The process that links several telescopes so they act as one large telescope, producing more detailed images as the distance between the individual telescopes increases.

1. The percentage of incoming sunlight a surface reflects.
2. The plane of Earth's orbit around the Sun.
5. Earth's shadow falls on the Moon.
6. Twice a year when the Sun is farthest from the celestial equator, changing daylight hours.
7. Dark smooth plains on the Moon from ancient volcanic eruptions.
10. All types of electromagnetic radiation arranged according to wavelength and frequency.
11. Loose rock and dust on the Moon's surface.
12. A depression on a surface formed by a meteorite impact.
14. Material blasted from an impact and falling back to the lunar surface.
16. The point where the Moon is closest to Earth in its orbit.
17. Heavily cratered, mountainous regions on the Moon.
20. Twice a year when day and night are nearly equal length.