1. IMPACT CRATER Bowl-shaped depressions on the surface of the Moon that are formed by meteor and comets crashing into the Moon.

2. RAY Long trails of debris that radiate outward from a Moon crater.

3. REGOLITH Dust and small pieces of rock that cover the surface of the Moon.

4. SUMMER SOLSTICE The longest day of the year which happens when the Sun is as far north of the equator as possible, around June 21.

5. WINTER SOLSTICE The shortest day of the year which happens when the Sun is as far south of the equator as possible, around December 21.

6. AUTUMNAL EQUINOX The time in the fall when day and night are equal in length because the Sun is directly over the equator, around September 21.

7. VERNAL EQUINOX The time in the spring when day and night are equal in length because the Sun is directly over the equator, around March 21.

8. SYNCHRONOUS ROTATION When the orbit and rotational periods of the Moon (or any other orbiting body) are equal.

9. SOLAR ECLIPSE When the Moon passes between the Sun and the Earth and blocks out all or part of the Sun.

10. LUNAR ECLIPSE When the Earth passes between the Sun and the Moon and the Earth’s shadow falls on the Moon. Only happens during a full moon.