The entire illuminated portion of the moon is on the back side of the moon, the half that we cannot see.Īt a full moon, the earth, moon, and sun are in approximate alignment, just as the new moon, but the moon is on the opposite side of the earth, so the entire sunlit part of the moon is facing us. The three objects are in approximate alignment (why "approximate" is explained below). It's probably easiest to understand the moon cycle in this order: new moon and full moon, first quarter and third quarter, and the phases in between.Īs shown in the above diagram, the new moon occurs when the moon is positioned between the earth and sun. If you'd like to examine the phases of the moon more closely, via computer software, you may be interested in this moon phases calendar software. So the basic explanation is that the lunar phases are created by changing angles (relative positions) of the earth, the moon and the sun, as the moon orbits the earth. Finally, please realize this diagram is only meant to demonstrate how the phases work the small inner moons in the diagram do not show the fact that the same side of the moon always faces Earth. Also note that the shadowed part of the moon is invisible to the naked eye in the diagram above, it is only shown for clarification purposes. At certain times we see both the sunlit portion and the shadowed portion - and that creates the various moon phase shapes we are all familiar with. Of course that is perfectly logical, but you need to visualize it in order to understand the phases. One important thing to notice is that exactly one half of the moon is always illuminated by the sun. When you do this, you'll "see" that the illuminated portion is on your left, just as you see in the large image. For the waning gibbous, third quarter, and waning crescent phases you have to mentally turn yourself upside down when imagining the line of sight. The large moon image shows what you would see at that point in the cycle. The dotted line from the earth to the moon represents your line of sight when looking at the moon. The moon phase name is shown alongside the image. The moon is shown at 8 key stages during its revolution around the earth. The earth, of course, is at the center of the diagram. Sunlight is shown coming in from the right. The illustration may look a little complex at first, but it's easy to explain.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |