Twilight is the time before sunrise or after sunset when sunlight scattered in the upper atmosphere illuminates the lower atmosphere and the surface of the Earth. The following guidelines have been established and widely accepted: ...
Twilight
Related Category: Astronomy: General
period between sunset and total darkness or between total darkness and sunrise.
twilight
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Twilight
The transition period from day to night (or night to day) when the sky is not completely dark, but the has not yet set (or risen).
twilight: the interval after sunset or before sunrise when the sun illuminates the upper atmosphere and hence it is not completely dark. It is determined by the sun's altitude falling within a given range, as follows: ...
Twilight - nautical Nautical twilight ends or begins when the Sun is 12° below the horizon.
Umbra Zone of maximum darkness in the shadow of a planet. Also the darkest part of a sunspot.
Twilight
The interval of time preceding sunrise and following sunset (see Sunrise; unset) during which the sky is partially illuminated.
Twilight -- For technical definition, please follow this link to the U.S. Naval Observatory Astronomical Applications website.
TWNC -- Two-Way Non-Coherent mode, in which a spacecraft's downlink is not based upon a received uplink from DSN.
Twilight of the Idols is a book by Friedrich Nietzsche, written in 1888, and published in 1889....
and The Antichrist
The Antichrist (book) ...
Twilight. By astronomical definition, the state of the sky when the Sun is below the horizon but by no more than 18 degrees.
U ...
Civil Twilight When the centre of the Sun is less than 6º below the horizon; normal daylight activities are possible.
Collimation The bringing of the optical components of a telescope into correct alignment.
twilight on every clear morning, unless blotted out by moonlight. It then presents a nearly vertical wedge-shaped form, the base of which extends 15° or 20° on each side of the point at which the ecliptic intersects the horizon.
twilight: the time after sunset or before sunrise when the sky is not fully dark.
Nautical twilight: The time when the Sun is 6-12 degrees below the horizon. Sky begins to get noticeably bright.
List of The Twilight Zone episodes
List of Xena: Warrior Princess episodes
List of Yes, (Prime) Minister episodes ...
civil twilight See twilight, note. civil year = calendar year. clad = cladding. cladding A coating placed on the surface of a material and usually bonded to the material. Also called clad.
civil twilight (NASA SP-7, 1965) See twilight, note. civil year (NASA SP-7, 1965) = calendar year. CL-600 challenger aircraft (NASA Thesaurus) Canadair turbofan aircraft with supercritical wings. clad (NASA SP-7, 1965) = cladding.
The Twilight Zone, "The Fugitive".
^ Del Rey, Lester (1980). The World of Science Fiction 1926-1976. Garland Publishing.
^ The American Heritage Dictionary of the English Language, Fourth Edition. Houghton Mifflin Company. 2000.
Scorpius, the zodiac's great Scorpion, wends its way from upper right to lower left in a morning twilight sky. Antares, lying toward the upper right, is the brightest star in the picture.
As more and more of this "surface" is hidden by the Moon, the sky dims as Earth spins toward an unnatural twilight.
As totality approaches the sky becomes dark and a twilight that can only be described as eerie begins to descend. Just before totality waves of shadow rushing rapidly from horizon to horizon may be visible.
The Bellamy Islands, inhabited only by the hardiest of creatures, are remote outposts in a surreal world of perpetual twilight. They comprise three islands: Sturge Island, Buckle Island, and Young Island.
Ptolemy also prepared a calendar that gave, in addition to weather indications, the risings and settings of the stars in the morning and evening twilight.
Telescope was only roughly aligned on Polaris during a few minutes I could spare at evening twilight and I used short exposures to avoid excessive trailing.
Civil twilight comprises the interval when the zenith distance, referred to the center of the Earth, of the central point of the Sun's disk is between 90°50' and 96°, nautical twilight comprises the interval from 96° to 102°, ...
On April 23, 2005, Spirit used its panoramic camera to photograph the martian twilight sky above Gusev crater.
By a week to 10 days into August, Mercury and Regulus will become lost to view in the bright twilight sky.
For several months during the year, in the twilight hours of early evening or the hours before sunrise, one can catch a glimpse of one or more bright planets.
An afterglow is a wide arc of glowing light that can sometimes be seen high in the western sky at twilight; it is caused by fine particles of dust scattering light in the upper atmosphere. 2.
Another Arabic name; Al Haris al Sama, the "Keeper of Heaven," perhaps came from the star's early visibility in the twilight owing to its great northern declination, ...
If you have binoculars, turn them on the Moon when it appears at twilight and when it appears high in the sky. Draw pictures of what you see. What differences do you notice in your two drawings? What color is the Moon seen near the horizon?
The zodiacal light appears as a faint triangle of light pointing upwards from the horizon, appearing after astronomical twilight (a little over an hour after local sunset, depending on your latitude) since it is overwhelmed by scattered sunlight in ...
Since the stars rise some four minutes earlier with each passing day, expect the stars of the Summer Triangle to light up the twilight dusk around middle to late June -- a sure harbinger of the change of seasons, of spring giving way to summer.
A text which dates to the era of Ramses VI (1148-1138 B.C.), refers to Mercury as "Seth in the evening twilight, a god in the morning twilight," conclusively showing that it was recognized as the same object in both the morning and evening.
While Mercury, the other inferior planet, reaches a maximum elongation of only 28° and is often difficult to discern in twilight, Venus is hard to miss when it is at its brightest.
Mercury is often visible with binoculars or even the unaided eye, but it is always very near the Sun and difficult to see in the twilight sky. There are several Web sites that show the current position of Mercury (and the other planets) in the sky.
of altitude above the horizon, and negative numbers indicate below the horizon --- with negative numbers usually being used in terms of how far below the horizon the sun is situated at a given time [for example, the boundary between civil twilight ...
Observed both at night and in twilight hours. Difficult to observe due to bright surface. Mars is similar to Earth because the surface and its atmosphere can been seen.
A great way to learn magnitudes is to watch a familiar constellation as the twilight sky turns darker.
On a clear evening the stars will appear at dusk according to their magnitude.
The planets Mars, Saturn and Mercury are all aligned together, huddling low on the western horizon, in the dying embers of twilight. Setting soon after the Sun, they will be a challenge to find as dusk turns to night.
But by 2013 the comet will be at its closest approach to the Sun, approximately 50 million kilometres distant, or roughly the same distance as Mercury, and will be visible low in the western sky after sunset during twilight.
The time that the sun is completely blocked out in a total eclipse takes just a few minutes, but is a spectacular sight. Day becomes twilight as the black shadow of the moon completely blocks the sun, but a halo effect surrounds it, ...
Saturn seen through the 28-inch telescope of the Royal Observatory, Greenwich. ŠTony Sizer Venus can be too bright for a telescope when the sky is dark. It is generally better to look in twilight or even in the day.
It is the closest planet to the Sun, therefore it has the shortest orbital period. Also due to its proximity to the Sun, it is very difficult to see in the morning or evening twilight. It rarely gets more than 25 degrees away from the Sun.
Students around the world helped polish the quarter-sized mirrors and will track this satellite visually for several months, during morning and evening twilight.
Finally William Shatner was chosen, who had science fiction experience before, acting in episodes of The Twilight Zone and The Outer Limits. The new captain was named James R. Kirk (later renamed James T. Kirk).
Due to the channelling of the charged solar particles along the Earth's magnetic field lines to the magnetic poles, the lower regions of the ionosphere (below 100 km) near the poles become heavily ionised, resulting in the eerie glow in the twilight ...
 See also: Light, Time, Earth, Planet, Sun
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