New Moon - The Moon's unilluminated side is facing the Earth. The
Moon is not visible (except during a solar eclipse).
Waxing Crescent - The Moon appears to be partly but less than
one-half illuminated by direct sunlight. The fraction of the Moon's disk
that is illuminated is increasing.
First Quarter - One-half of the Moon appears to be illuminated by
direct sunlight. The fraction of the Moon's disk that is illuminated is
increasing.
Waxing Gibbous - The Moon appears to be more than one-half but
not fully illuminated by direct sunlight. The fraction of the Moon's disk
that is illuminated is increasing.
Full Moon - The Moon's illuminated side is facing the Earth. The
Moon appears to be completely illuminated by direct sunlight.
Waning Gibbous - The Moon appears to be more than one-half but
not fully illuminated by direct sunlight. The fraction of the Moon's disk
that is illuminated is decreasing.
Last Quarter - One-half of the Moon appears to be illuminated by
direct sunlight. The fraction of the Moon's disk that is illuminated is
decreasing.
Waning Crescent - The Moon appears to be partly but less than
one-half illuminated by direct sunlight. The fraction of the Moon's disk
that is illuminated is decreasing.
Following waning crescent is New Moon, beginning a repetition of the
complete phase cycle of 29.5 days average duration. The time in days
counted from the time of New Moon is called the Moon's "age". Each
complete cycle of phases is called a "lunation".
Because the cycle of the phases is shorter than most calendar
months, the phase of the Moon at the very beginning of the month
usually repeats at the very end of the month. When there are two Full
Moons in a month (which occurs, on average, every 2.7 years), the
second one is called a "Blue Moon".
Moon is not visible (except during a solar eclipse).
Waxing Crescent - The Moon appears to be partly but less than
one-half illuminated by direct sunlight. The fraction of the Moon's disk
that is illuminated is increasing.
First Quarter - One-half of the Moon appears to be illuminated by
direct sunlight. The fraction of the Moon's disk that is illuminated is
increasing.
Waxing Gibbous - The Moon appears to be more than one-half but
not fully illuminated by direct sunlight. The fraction of the Moon's disk
that is illuminated is increasing.
Full Moon - The Moon's illuminated side is facing the Earth. The
Moon appears to be completely illuminated by direct sunlight.
Waning Gibbous - The Moon appears to be more than one-half but
not fully illuminated by direct sunlight. The fraction of the Moon's disk
that is illuminated is decreasing.
Last Quarter - One-half of the Moon appears to be illuminated by
direct sunlight. The fraction of the Moon's disk that is illuminated is
decreasing.
Waning Crescent - The Moon appears to be partly but less than
one-half illuminated by direct sunlight. The fraction of the Moon's disk
that is illuminated is decreasing.
Following waning crescent is New Moon, beginning a repetition of the
complete phase cycle of 29.5 days average duration. The time in days
counted from the time of New Moon is called the Moon's "age". Each
complete cycle of phases is called a "lunation".
Because the cycle of the phases is shorter than most calendar
months, the phase of the Moon at the very beginning of the month
usually repeats at the very end of the month. When there are two Full
Moons in a month (which occurs, on average, every 2.7 years), the
second one is called a "Blue Moon".
CURRENT MOON
| Tide Predictions from Tides.Info |
What is Universal Time?
The times of various events, particularly astronomical and weather phenomena, are often given in
"Universal Time" (abbreviated UT) which is sometimes referred to, now colloquially, as "Greenwich
Mean Time" (abbreviated GMT). The two terms are often used loosely to refer to time kept on the
Greenwich meridian (longitude zero), five hours ahead of Eastern Standard Time. Times given in
UT are almost always given in terms of a 24-hour clock. Thus, 14:42 (often written simply 1442) is
2:42 p.m., and 21:17 (2117) is 9:17 p.m. Sometimes a Z is appended to a time to indicate UT, as
in 0935Z.
When a precision of one second or better is needed, however, it is necessary to be more specific
about the exact meaning of UT. For that purpose different designations of Universal Time have
been adopted. In astronomical and navigational usage, UT often refers to a specific time called
UT1, which is a measure of the rotation angle of the Earth as observed astronomically. It is
affected by small variations in the rotation of the Earth, and can differ slightly from the civil time
on the Greenwich meridian. Times which may be labeled "Universal Time" or "UT" in data
provided by the Astronomical Applications Department of the U.S. Naval Observatory (for
example, in the annual almanacs) conform to this definition.
However, in the most common civil usage, UT refers to a time scale called "Coordinated Universal
Time" (abbreviated UTC), which is the basis for the worldwide system of civil time. This time scale
is kept by time laboratories around the world, including the U.S. Naval Observatory, and is
determined using highly precise atomic clocks. The International Bureau of Weights and
Measures makes use of data from the timing laboratories to provide the international standard
UTC which is accurate to approximately a nanosecond (billionth of a second) per day. The length
of a UTC second is defined in terms of an atomic transition of the element cesium under specific
conditions, and is not directly related to any astronomical phenomena.
UTC is the time distributed by standard radio stations that broadcast time, such as WWV and
WWVH. It can also be obtained readily from the Global Positioning System (GPS) satellites. The
difference between UTC and UT1 is made available electronically and broadcast so that
navigators can obtain UT1. UTC is the basis for civil standard time in the U.S. and its territories.
Standard time within U.S. time zones is an integral number of hours offset from UTC.
UTC is equivalent to the civil time for Iceland, Liberia, Morocco, Senegal, Ghana, Mali, Mauritania,
and several other countries. During the winter months, UTC is also the civil time scale for the
United Kingdom and Ireland.
One can think of UT1 as being a time determined by the rotation of the Earth, over which we have
no control, whereas UTC is a human invention. It is relatively easy to manufacture highly precise
clocks that keep UTC, while the only "clock" keeping UT1 precisely is the Earth itself.
Nevertheless, it is desirable that our civil time scale not be very different from the Earth's time, so,
by international agreement, UTC is not permitted to differ from UT1 by more than 0.9 second.
When it appears that the difference between the two kinds of time may approach this limit, a
one-second change called a "leap second" is introduced into UTC. This occurs on average about
once every year to a year and a half.
Historical Note:
Greenwich Mean Time is a widely used historical term, but one that has been used in several
ways. Because of the ambiguity, its use is no longer recommended in technical contexts.
Prior to 1925, in astronomical and nautical almanacs, a day of Greenwich Mean Time began at
noon. This reckoning of Greenwich Mean Time is now called Greenwich Mean Astronomical Time,
and is no longer used. Persons using old editions of the almanacs for historical research should
be aware of the previous convention.
Copyright© 2006 - 2009 BobberStop.com
The times of various events, particularly astronomical and weather phenomena, are often given in
"Universal Time" (abbreviated UT) which is sometimes referred to, now colloquially, as "Greenwich
Mean Time" (abbreviated GMT). The two terms are often used loosely to refer to time kept on the
Greenwich meridian (longitude zero), five hours ahead of Eastern Standard Time. Times given in
UT are almost always given in terms of a 24-hour clock. Thus, 14:42 (often written simply 1442) is
2:42 p.m., and 21:17 (2117) is 9:17 p.m. Sometimes a Z is appended to a time to indicate UT, as
in 0935Z.
When a precision of one second or better is needed, however, it is necessary to be more specific
about the exact meaning of UT. For that purpose different designations of Universal Time have
been adopted. In astronomical and navigational usage, UT often refers to a specific time called
UT1, which is a measure of the rotation angle of the Earth as observed astronomically. It is
affected by small variations in the rotation of the Earth, and can differ slightly from the civil time
on the Greenwich meridian. Times which may be labeled "Universal Time" or "UT" in data
provided by the Astronomical Applications Department of the U.S. Naval Observatory (for
example, in the annual almanacs) conform to this definition.
However, in the most common civil usage, UT refers to a time scale called "Coordinated Universal
Time" (abbreviated UTC), which is the basis for the worldwide system of civil time. This time scale
is kept by time laboratories around the world, including the U.S. Naval Observatory, and is
determined using highly precise atomic clocks. The International Bureau of Weights and
Measures makes use of data from the timing laboratories to provide the international standard
UTC which is accurate to approximately a nanosecond (billionth of a second) per day. The length
of a UTC second is defined in terms of an atomic transition of the element cesium under specific
conditions, and is not directly related to any astronomical phenomena.
UTC is the time distributed by standard radio stations that broadcast time, such as WWV and
WWVH. It can also be obtained readily from the Global Positioning System (GPS) satellites. The
difference between UTC and UT1 is made available electronically and broadcast so that
navigators can obtain UT1. UTC is the basis for civil standard time in the U.S. and its territories.
Standard time within U.S. time zones is an integral number of hours offset from UTC.
UTC is equivalent to the civil time for Iceland, Liberia, Morocco, Senegal, Ghana, Mali, Mauritania,
and several other countries. During the winter months, UTC is also the civil time scale for the
United Kingdom and Ireland.
One can think of UT1 as being a time determined by the rotation of the Earth, over which we have
no control, whereas UTC is a human invention. It is relatively easy to manufacture highly precise
clocks that keep UTC, while the only "clock" keeping UT1 precisely is the Earth itself.
Nevertheless, it is desirable that our civil time scale not be very different from the Earth's time, so,
by international agreement, UTC is not permitted to differ from UT1 by more than 0.9 second.
When it appears that the difference between the two kinds of time may approach this limit, a
one-second change called a "leap second" is introduced into UTC. This occurs on average about
once every year to a year and a half.
Historical Note:
Greenwich Mean Time is a widely used historical term, but one that has been used in several
ways. Because of the ambiguity, its use is no longer recommended in technical contexts.
Prior to 1925, in astronomical and nautical almanacs, a day of Greenwich Mean Time began at
noon. This reckoning of Greenwich Mean Time is now called Greenwich Mean Astronomical Time,
and is no longer used. Persons using old editions of the almanacs for historical research should
be aware of the previous convention.
Copyright© 2006 - 2009 BobberStop.com
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| Lunar Phases |
