| A | B |
|---|
| APOGEE | POINT OF THE MOON'S ORBIT FARTHEST FROM THE EARTH |
| ATMOSPHERE | ENVELOPE OF GASES SURROUNDING THE EARTH |
| AUTUMNAL EQUINOX | FIRST DAY OF AUTUMN |
| ECLIPSE | TOTAL OR PARTIAL BLOCKING OUT OF THE SUN OR MOON |
| EQUATOR | IMAGINARY LINE AROUND THE EARTH THAT DIVIDES THE EARTH INTO HEMISPHERES; PARALLEL HALFWAY BETWEEN THE NORTH AND SOUTH POLES |
| FULL MOON | PHASE OF THE MOON WHEN THE ENTIRE LIGHTED SIDE OF THE MOON IS VISIBLE |
| HEMISPHERE | NORTHERN OR SOUTHERN HALF OF THE EARTH |
| HIGHLANDS | MOUNTAINS OF THE MOON |
| HYDROSPHERE | PART OF THE EARTH'S SURFACE COVERED BY WATER |
| LOW TIDE | LOWEST LEVEL OF THE OCEAN THAT OCCURS BETWEEN THE TWO HIGH TIDES |
| LUNAR | REFERRING TO THE MOON |
| LUNAR ECLIPSE | BLOCKING OUT OF THE MOON WHEN THE MOON PASSES THROUGH THE EARTH'S SHADOW |
| MAGNETOSPHERE | MAGNETIC FIELD OF THE EARTH |
| MARIA | DARK, BROAD, SMOOTH LOWLAND AREA ON THE MOON |
| NEAP TIDE | LOWER HIGH TIDE THAN NORMAL THAT OCCURS DURING THE FIRST AND LAST QUARTER PHASES OF THE MOON |
| NEW MOON | PHASE OF THE MOON WHEN IT IS NOT VISIBLE IN THE SKY |
| PENUMBRA | OUTER AREA OF A SHADOW CAST BY ONE OBJECT IN SPACE ONTO ANOTHER OBJECT IN SPACE IN WHICH THE LIGHT IS ONLY PARTLY BLOCKED |
| PERIGEE | POINT OF THE MOON'S ORBIT CLOSEST TO THE EARTH |
| RILLE | LONG VALLEY ON THE MOON |
| SOLAR ECLIPSE | ECLIPSE OF THE SUN THAT OCCURS WHEN THE MOON IS DIRECTLY BETWEEN THE SUN AND THE EARTH |
| SPRING TIDE | HIGHER HIGH TIDE THAT OCCURS DURING THE FULL AND NEW MOON PHASES |
| SUMMER SOLSTICE | TIME OF YEAR WHEN THE NORTHERN HEMISPHERE HAS ITS LONGEST DAY AND THE SOUTHERN HEMISPHERE HAS ITS SHORTEST DAY |
| TIDE | RISE AND FALL OF THE OCEANS CAUSED BY THE MOON'S GRAVITATIONAL PULL ON THE EARTH |
| TOTAL ECLIPSE | TOTAL BLOCKING OUT OF THE MOON WHEN THE MOON PASSES THROUGH THE UMBRA OF THE EARTH'S SHADOW |
| UMBRA | INNER AREA OF A SHADOW CAST BY ONE OBJECT IN SPACE ONTO ANOTHER OBJECT IN SPACE IN WHICH THE LIGHT IS COMPLETELY BLOCKED OUT |
| VAN ALLEN RADIATION BELT | BAND OF HIGH RADIATION AROUND THE EARTH THAT CAPTURES PARTICLES GIVEN OFF BY THE SUN |
| VERNAL EQUINOX | FIRST DAY OF SPRING |
| WANING CRESCENT | PHASE OF THE MOON BETWEEN ONE-HALF AND NEW MOON WHEN THE LIGHTED AREA OF THE MOON APPEARS TO GROW SMALLER |
| WANING-GIBBOUS | PHASE OF THE MOON BETWEEN FULL AND ONE HALF WHEN THE LIGHTED AREA OF THE MOON APPEARS TO GROW SMALLER |
| WAXING-CRESCENT | PHASE OF THE MOON BETWEEN THE NEW MOON AND ON HALF MOON WHEN THE LIGHTED AREA OF THE MOON APPEARS TO GROW LARGER |
| WAXING GIBBOUS | PHASE OF THE MOON BETWEEN ONE HALF AND FULL WHEN THE LIGHTED AREA OF THE MOON APPEARS TO GROW LARGER |
| WINTER SOLSTICE | TIME OF THE YEAR WHEN THE NORTHERN HEMISPHERE HAS ITS SHORTEST DAY AND THE SOUTHERN HEMISPHERE HAS ITS LONGEST DAY |
| EQUINOX | DATE ON WHICH DAY AND NIGHT ARE OF EQUAL LENGTH |
| HIGH TIDE | BULGE IN THE OCEAN ON THE SIDE OF THE EARTH FACING THE MOON AND ON THE OPPOSITE SIDE |
