2012 sunrise, sunsets & moon phases

2012 Sunrise, Sunsets & Moon Phases

Samara, Guanacaste, Costa Rica ~ Pacific Ocean Coast
Latitude 9.8833 ▪ Longitude -85.5333 ▪ Altitude 3 feet
Lat (DMS) 9° 52' 60N ▪ Long (DMS) 85° 31' 60W ▪ Altitude 1 meter
Time zone (est) UTC-6

Moon Phases Calendar

Because Samara is near the equator ~ Sunrise at 5:30 am & Sunset at 5:30 pm, roughly, all year long.

Moon phases

Lunar phases are the result of seeing the illuminated half of the Moon from different viewing geometries; they are not caused by shadows of the Earth on the Moon that occur during a lunar eclipse. The Moon exhibits different phases as the relative geometry of the Sun, Earth, and Moon change, appearing as a full moon when the Sun and Moon are on opposite sides of the Earth, and as a new moon (also named dark moon, as it is not visible at night) when they are on the same side. The phases of full moon and new moon are examples of syzygies, which occur when the Earth, Moon, and Sun lie (approximately) in a straight line. The time between two full moons (and between successive occurrences of the same phase) is about 29.53 days (29 days, 12 hours, 44 minutes) on average. This synodic month is longer than the time it takes the Moon to make one orbit about the Earth with respect to the fixed stars (the sidereal month), which is about 27.32 days. This difference is caused by the fact that the Earth-Moon system is orbiting about the Sun at the same time the Moon is orbiting about the Earth. The actual time between two syzygies is variable because the orbit of the Moon is elliptic and subject to various periodic perturbations, which change the velocity of the Moon.

It might be expected that once every month when the Moon passes between Earth and the Sun during a new moon, its shadow would fall on Earth causing a solar eclipse. Likewise, during every full moon, we might expect the Earth's shadow to fall on the Moon, causing a lunar eclipse. We do not observe a solar and lunar eclipse every month because the plane of the Moon's orbit around the Earth is tilted by about 5 degrees with respect to the plane of Earth's orbit around the Sun. Thus, when new and full moons occur, the Moon usually lies to the north or south of a direct line through the Earth and Sun. Although an eclipse can only occur when the Moon is either new or full, it must also be positioned very near the intersection of Earth's orbit plane about the Sun and the Moon's orbit plane about the Earth (that is, at one of its nodes). This happens about twice per year, and so there are between 4 and 7 eclipses in a calendar year. Most of these are quite insignificant; major eclipses of the Moon or Sun are relatively rare.

Name of lunar phases

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 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.

Animation of the Moon as it cycles through its phases, as seen from the Northern Hemisphere. The apparent wobbling of the Moon is known as libration.

Animation of the Moon as it cycles through its phases, as seen from the Northern Hemisphere. The apparent wobbling of the Moon is known as libration.

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.

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 towards 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 towards a new moon). Assuming that one is in the northern hemisphere, the right portion of the Moon is the part that is always growing.