Lunar phase

As phases of the moon is referred to the changing figures of light of the moon. They result from the perspective position change its day - night boundary relative to the Earth during its Erdumlaufes. Commonly used is the division into four quarters, each about a week long.

• A distinction is commonly full moon, waning moon, waxing moon and new moon.
• New moon, full moon and the two half moons is called the principal phases.
• In apparent contradiction to the more general designation Crescent - this is the half-phase ( dichotomy ) - astronomers refer to the full cycle of the moon and call the waxing half phase first quarter, the decreasing accordingly last quarter.
• The waxing moon is V.A. to see in the evening sky or in the first half of the night, the waning morning sky
• Before the first and after the last quarter of the Earth's satellite appears as a crescent moon. If they after new moon as a very thin crescent is first visible in the evening sky, one speaks of the Neulicht, at its last visible in the morning sky about two days before the New Moon of Altlicht.

Overview

A revolution of the moon around the earth at which the moon again occupies the same position relative to the sun, takes an average of about 29.53 days ( 29 days, 12 hours and 43 minutes ) and is called the synodic month. It amounts to less than a month. In fact, both the term and the length of a month by the synodic orbital period of the Moon are derived. The actual length of a single period - a lunation - is relatively large fluctuations ( see the accurate average: sidereal period).

Depending on the position of the moon, the earth and the sun to each other from Earth different phase angle of the moon to observe the sun. These cause the changing shapes of the moon in the sky.

How we perceive on earth the moon here, it is clear from the graph below.

A: Earth B: Earth's Moon C: the direction of rotation of the moon D: Moon's orbit around the Earth E: sun rays

The proportions of the objects on the graphics and their distances do not correspond to each other the natural proportions.

Visibility

The Moon is a passive light source, that is, it scatters only the light of the active light source sun.

• The lunar surface must be illuminated by the sun.
• Non -illuminated parts of the surface are not passive light sources and therefore theoretically not visible, although there is nothing between them and the observer. In fact, however, they are illuminated by the daylight side of the Earth, which is (before the first and after the last quarter ) often seen with crescent moon phases as earthshine. Furthermore, the erdzugewandte side of the moon is slightly illuminated by the refracted light to the earth's atmosphere. Therefore, the full moon is barely visible even with lunar eclipses and appear copper-colored.

• The times for the moon rising and setting vary with the phases and (minor ) with the season. Details are complicated to that of the Earth and because of the inclined axis of the earth because of the inclination of the lunar orbit plane. In addition, the deviations between the actual solar time and the time zone in which the observer is to note, especially during the validity of the DST:

• In new moon the moon goes something along with the sun in the morning and in the evening under.
• In the first quarter of the moon around noon and goes to midnight under.
• At full moon, he goes on and at dawn at dusk under and is visible all night ( about 8 hours in summer, in winter up to 16 hours).
• In the last quarter, he goes on, and southward toward the north below.

Historical

The phases of the moon were once called Wadel.

Light effect of the moon

In the phases of the moon the earthly night is brightened very different, and astronomers must ( around full moon) with optical telescopes usually omit "moon nights " during observations.

As a new moon the Earth -facing side of the moon is without rails of the sun, so dark and goes - covered by the atmospheric sky blue - close to the sun with this on and under. ( Visible is the new moon every few years when a solar eclipse occurs at its own site ). A narrow Neulichtsichel is the sun still so close that they can only be visible shortly after sunset. A few days later, the crescent can be seen already in the afternoon and seems half the night until his demise at midnight.

Four effects cause the particularly strong effect of light around the time of the full moon:

• We see from Earth, a fully -illuminated ball, so the moon's disk with the largest solid angle illuminated. The variable lunar distance can make additional ± 10%.
• The reflection effect ( albedo) of the moon is strongest, because now - from earthly perspective - for large areas of the lunar surface, the incident angle of sunlight is perpendicular and close to the viewing angle. The partially diffuse reflection of the lunar soil is true - of the apparent lunar center toward - the maximum earth.
• At midnight, the otherwise darkest part of the night, the moon is highest and its light is hitting the ground at a steep angle. At high moon's position ( esp. in winter) then the atmospheric scattering of its light is at its lowest.
• The full moon is visible all night and dissolves at its rising and setting with the sun gear straight off.

High standing full moon illuminated under a clear sky, the earth, even at sea level a few hours so bright that the dark - adapted human eye colors are seen, ie a meadow appears green. The illumination is then to 0.25 lux, 250 times a starry new moon (0.001 lx).

The more you without artificial light sources (city, electric power, lighting of vehicle and the road, hidden by mountains, vegetation, without fire ) resides, moved, or lives, the more one than the seeing of moonlight is - depending on moon phase and cloud cover - in its potential impact at night. On a lonely road, no shadow of trees, one has at the full moon view, which is actually sufficient for running and ( lonely ) cycling and is uniform light to the horizon. Street lighting and bike light is about 10 lux or more at least 40 times as bright, but only in the illuminated area. Such lights can be largely beside fade the lighting remotely by moonlight.

Esoteric

Numerous books a connection between moon phases and different life is made. So shall affect the others have to sleep, accidents, complications during surgery and childbirth or to the hair growth of the position of the moon. For no such assertion studies could not find evidence, therefore they are considered refuted.

In particular, the alleged moon phase of 28 days influenced for over a hundred years in the German-speaking countries, the idea of ​​" biorhythms " that will affect all areas of life.

Moon phase and tidal range

The tides are caused by the gravitational especially the nearby moon, the earth once less often encircled in 29.53 days as it does the sun (apparently). During a lunar cycle of 24 49min water is contracted twice the tidal wave: at moon high and 12h 24min later. (The actual trained tidal wave runs as a flow process in contrast, albeit at different times around the equator of the earth, builds up on coasts, spilling into constrictions high and resonates in places. )

The sun exerts in the sea about 45% of the tidal pull of the moon. It supports the effect of the moon at a maximum when the three celestial bodies involved are on a line, ie, at full and new moon: All 14.77 days occurs at spring tide, so the highest tidal range between high and low tide. In contrast, neap tide, when the moon - earth - sun are perpendicular to each other in an L- configuration, ie at half moon.

To show the phases of the moon - in theory to the phase lag of the tidal wave, so a little ahead of haste - as an indicator of the exact sequence of high and low tides, but which is overmolded practical nor of effects of wind and weather (air pressure).

Phases of low tidal range mean low currents near the coast and can be used for calmer shipping, construction, diving or landing. In contrast, Springtide highest and lowest water levels and strong currents have very different uses, a flood surge can suck about surfing.

Crib

The traditional German rule of thumb for the phases of the moon based on the German cursive: When writing the letter "a", start with a curved arc to the left. This shows the orientation of the thin crescent of the waning moon, as seen by an observer in the northern hemisphere of the earth. The cursive z is started with an arched bow to the right and thus shows the waxing moon.

Increasingly

A more modern shopping rule uses the characters "( ", or " bracket" for "apple " and the character " ) ", or " bracket" for " increasingly " where the crescent is indicated by the respective shape of the clip.