Names of Lunar Phases
The phases of the Moon have been given the following names, in sequential order:
| Phase | Northern Hemisphere | Southern Hemisphere | Visibility | Standard time of culmination (mid-phase) |
|---|---|---|---|---|
| New moon | Not visible, traditionally Moon's first visible crescent | after sunset | 12 noon | |
| Waxing crescent moon | Right 1–49% visible | Left 1–49% visible | afternoon and post-dusk | 3 pm |
| First quarter moon | Right 50% visible | Left 50% visible | afternoon and early night | 6 pm |
| Waxing gibbous moon | Right 51–99% visible | Left 51–99% visible | late afternoon and most of night | 9 pm |
| Full moon | Fully visible | Fully visible | sunset to sunrise (all night) | 12 midnight |
| Waning gibbous moon | Left 51–99% visible | Right 51–99% visible | most of night and early morning | 3 am |
| Third (last) quarter moon | Left 50% visible | Right 50% visible | late night and morning | 6 am |
| Waning crescent moon | Left 1–49% visible | Right 1–49% visible | pre-dawn and morning | 9 am |
| Dark moon | Not visible, traditionally Moon's last visible crescent | before sunrise | 12 noon | |
When the Sun and Moon are aligned on the same side of the Earth the Moon is "new", and the side of the Moon visible from Earth is not illuminated by the Sun. As the Moon waxes (the amount of illuminated surface as seen from Earth is increasing), the lunar phases progress from new moon, crescent moon, first-quarter moon, gibbous moon and full moon phases, before returning through the gibbous moon, third-quarter (or last quarter) moon, crescent moon and new moon phases. The terms old moon and new moon are interchangeable, although new moon is more common. Half moon is often used to mean the first- and third-quarter moons, while the term 'quarter' refers to the extent of the moon's cycle around the Earth, not its shape.
When a sphere is illuminated on one hemisphere and viewed from a different angle, the portion of the illuminated area that is visible will have a two-dimensional shape defined by the intersection of an ellipse and circle (where the major axis of the ellipse coincides with a diameter of the circle). If the half-ellipse is convex with respect to the half-circle, then the shape will be gibbous (bulging outwards), whereas if the half-ellipse is concave with respect to the half-circle, then the shape will be a crescent. When a crescent Moon occurs, the phenomenon of Earthshine may be apparent, where the night side of the Moon faintly reflects light from the Earth.
In the northern hemisphere, if the left side of the Moon is dark then the light part is growing, and the Moon is referred to as waxing (moving toward a full moon). If the right side of the Moon is dark then the light part is shrinking, and the Moon is referred to as waning (moving toward a new moon). Assuming that the viewer is in the northern hemisphere, the right portion of the Moon is the part that is always growing (i.e., if the right side is dark, the Moon is growing darker; if the right side is lit, the Moon is growing lighter). In the southern hemisphere the Moon is observed from a perspective inverted to that of the northern hemisphere, so the opposite sides appear to grow (wax) and shrink (wane).
Read more about this topic: Lunar Phase
Famous quotes containing the words names, lunar and/or phases:
“I introduced her to Elena, and in that life-quickening atmosphere of a big railway station where everything is something trembling on the brink of something else, thus to be clutched and cherished, the exchange of a few words was enough to enable two totally dissimilar women to start calling each other by their pet names the very next time they met.”
—Vladimir Nabokov (1899–1977)
“A bird half wakened in the lunar noon
Sang halfway through its little inborn tune.”
—Robert Frost (1874–1963)
“But parents can be understanding and accept the more difficult stages as necessary times of growth for the child. Parents can appreciate the fact that these phases are not easy for the child to live through either; rapid growth times are hard on a child. Perhaps it’s a small comfort to know that the harder-to-live-with stages do alternate with the calmer times,so parents can count on getting periodic breaks.”
—Saf Lerman (20th century)