A lunar eclipse is an astronomical event that occurs when the Moon moves into the Earth's shadow, causing the Moon to be darkened. Such an alignment occurs during an eclipse season, approximately every six months, during the full moon phase, when the Moon's orbital plane is closest to the plane of the Earth's orbit.
The green flash and green ray are meteorological optical phenomena that sometimes occur transiently around the moment of sunset or sunrise. When the conditions are right, a distinct green spot is briefly visible above the Sun's upper limb; the green appearance usually lasts for no more than two seconds. Rarely, the green flash can resemble a green ray shooting up from the sunset or sunrise point.
In astronomy, an analemma is a diagram showing the position of the Sun in the sky as seen from a fixed location on Earth at the same mean solar time over the course of a year. The change of position is a result of the shifting of the angle in the sky of the path that the Sun takes in respect to the stars. The diagram resembles a figure eight. Globes of the Earth often display an analemma as a two-dimensional figure of equation of time vs. declination of the Sun.
Sunrise is the moment when the upper rim of the Sun appears on the horizon in the morning, at the start of the Sun path. The term can also refer to the entire process of the solar disk crossing the horizon.
The sky is an unobstructed view upward from the surface of the Earth. It includes the atmosphere and outer space. It may also be considered a place between the ground and outer space, thus distinct from outer space.
The four cardinal directions, or cardinal points, are the four main compass directions: north, south, east, and west, commonly denoted by their initials N, S, E, and W respectively. Relative to north, the directions east, south, and west are at 90 degree intervals in the clockwise direction.
A transient lunar phenomenon (TLP) or lunar transient phenomenon (LTP) is a short-lived change in light, color or appearance on the surface of the Moon. The term was created by Patrick Moore in his co-authorship of NASA Technical Report R-277 Chronological Catalog of Reported Lunar Events, published in 1968.
In astronomy, an extraterrestrial sky is a view of outer space from the surface of an astronomical body other than Earth.
The night sky is the nighttime appearance of celestial objects like stars, planets, and the Moon, which are visible in a clear sky between sunset and sunrise, when the Sun is below the horizon.
The antisolar point is the abstract point on the celestial sphere directly opposite the Sun from an observer's perspective. This means that the antisolar point lies above the horizon when the Sun is below it, and vice versa. On a sunny day, the antisolar point can be easily found; it is located within the shadow of the observer's head. Like the zenith and nadir, the antisolar point is not fixed in three-dimensional space, but is defined relative to the observer. Each observer has an antisolar point that moves as the observer changes position.
The Belt of Venus – also called Venus's Girdle, the antitwilight arch, or antitwilight – is an atmospheric phenomenon visible shortly before sunrise or after sunset, during civil twilight. It is a pinkish glow that surrounds the observer, extending roughly 10–20° above the horizon. It appears opposite to the afterglow, which it also reflects.
Identifying unidentified flying objects (UFOs) is a difficult task due to the normally poor quality of the evidence provided by those who report sighting the unknown object. Observations and subsequent reporting are often made by those untrained in astronomy, atmospheric phenomena, aeronautics, physics, and perception. Nevertheless, most officially investigated UFO sightings, such as from the U.S. Air Force's Project Blue Book, have been identified as being due to honest misidentifications of natural phenomena, aircraft, or other prosaic explanations. In early U.S. Air Force attempts to explain UFO sightings, unexplained sightings routinely numbered over one in five reports. However, in early 1953, right after the CIA's Robertson Panel, percentages of unexplained sightings dropped precipitously, usually being only a few percent in any given year. When Project Blue Book closed down in 1970, only 6% of all cases were classified as being truly unidentified.
A mirage of an astronomical object is a meteorological optical phenomenon, in which light rays are bent to produce distorted or multiple images of an astronomical object. The mirages might be observed for such celestial objects as the Sun, the Moon, the planets, bright stars, and very bright comets. The most commonly observed of these are sunset and sunrise mirages.
The Rayleigh sky model describes the observed polarization pattern of the daytime sky. Within the atmosphere, Rayleigh scattering of light by air molecules, water, dust, and aerosols causes the sky's light to have a defined polarization pattern. The same elastic scattering processes cause the sky to be blue. The polarization is characterized at each wavelength by its degree of polarization, and orientation.
Atmospheric optics is "the study of the optical characteristics of the atmosphere or products of atmospheric processes .... [including] temporal and spatial resolutions beyond those discernible with the naked eye". Meteorological optics is "that part of atmospheric optics concerned with the study of patterns observable with the naked eye". Nevertheless, the two terms are sometimes used interchangeably.
Earth's shadow is the shadow that Earth itself casts through its atmosphere and into outer space, toward the antisolar point. During the twilight period, the shadow's visible fringe – sometimes called the dark segment or twilight wedge – appears as a dark and diffuse band just above the horizon, most distinct when the sky is clear.
An April 1561 broadsheet by Hans Glaser described a mass sighting of celestial phenomena or unidentified flying objects (UFO) above Nuremberg. Ufologists have speculated that these phenomena may have been extraterrestrial spacecraft. Skeptics assert that the phenomenon was likely to have been another atmospheric phenomena, such as a sun dog, although the print doesn't fit the usual classic description of the phenomena.
Moonrise and moonset are times when the upper limb of the Moon appears above the horizon and disappears below it, respectively. The exact times depend on the lunar phase and declination, as well as the observer's location. As viewed from outside the polar circles, the Moon, like all other celestial objects outside the circumpolar circle, rises from the eastern half of the horizon and sets into the western half due to Earth's rotation.
1665 celestial phenomenon over Stralsund refers to reports from Stralsund, Swedish Pomerania during 1665 of unusual flying ships allegedly seen over Stralsund, now sometimes considered UFOs in a modern context. These ships were described as being dark-grey or having a color being "that of the rising Moon" and sometimes said to be covered by a dome like that of a hat as well as being saucer-shaped like a plate, often said to be seen flying over St. Nicholas Church near the Baltic Sea, where they would hover until the evening.
