A mirage of an astronomical object is a

meteorological Meteorology is the scientific study of the Earth's atmosphere and short-term atmospheric phenomena (i.e. weather), with a focus on weather forecasting. It has applications in the military, aviation, energy production, transport, agriculture ...

optical phenomenon Optical phenomena are any observable events that result from the interaction of light and matter. All optical phenomena coincide with quantum phenomena. Common optical phenomena are often due to the interaction of light from the Sun or Moon with ...

, in which light rays are bent to produce distorted or multiple images of an

astronomical object An astronomical object, celestial object, stellar object or heavenly body is a naturally occurring physical entity, association, or structure that exists within the observable universe. In astronomy, the terms ''object'' and ''body'' are of ...

. The

mirage A mirage is a naturally-occurring optical phenomenon in which light rays bend via refraction to produce a displaced image of distant objects or the sky. The word comes to English via the French ''(se) mirer'', from the Latin ''mirari'', mean ...

s might be observed for such celestial objects as the

Sun The Sun is the star at the centre of the Solar System. It is a massive, nearly perfect sphere of hot plasma, heated to incandescence by nuclear fusion reactions in its core, radiating the energy from its surface mainly as visible light a ...

, the

Moon The Moon is Earth's only natural satellite. It Orbit of the Moon, orbits around Earth at Lunar distance, an average distance of (; about 30 times Earth diameter, Earth's diameter). The Moon rotation, rotates, with a rotation period (lunar ...

, the

planet A planet is a large, Hydrostatic equilibrium, rounded Astronomical object, astronomical body that is generally required to be in orbit around a star, stellar remnant, or brown dwarf, and is not one itself. The Solar System has eight planets b ...

s, bright

star A star is a luminous spheroid of plasma (physics), plasma held together by Self-gravitation, self-gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked eye at night sk ...

s, and very bright

comet A comet is an icy, small Solar System body that warms and begins to release gases when passing close to the Sun, a process called outgassing. This produces an extended, gravitationally unbound atmosphere or Coma (cometary), coma surrounding ...

s. The most commonly observed of these are

sunset Sunset (or sundown) is the disappearance of the Sun at the end of the Sun path, below the horizon of the Earth (or any other astronomical object in the Solar System) due to its Earth's rotation, rotation. As viewed from everywhere on Earth, it ...

and

sunrise Sunrise (or sunup) 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. Terminology Although the S ...

mirages.

Mirages versus refraction

Mirage A mirage is a naturally-occurring optical phenomenon in which light rays bend via refraction to produce a displaced image of distant objects or the sky. The word comes to English via the French ''(se) mirer'', from the Latin ''mirari'', mean ...

s are distinguished from other phenomena caused by

atmospheric refraction Atmospheric refraction is the deviation of light or other electromagnetic wave from a straight line as it passes through the atmosphere due to the variation in air density as a function of height. This refraction is due to the velocity of light ...

. One of the most prominent features of mirages is that a mirage might only produce images vertically, not sideways, while a simple refraction might distort and bend the images in any way. The

distortion In signal processing, distortion is the alteration of the original shape (or other characteristic) of a signal. In communications and electronics it means the alteration of the waveform of an information-bearing signal, such as an audio signal ...

in both images displayed in this section was caused by

refraction In physics, refraction is the redirection of a wave as it passes from one transmission medium, medium to another. The redirection can be caused by the wave's change in speed or by a change in the medium. Refraction of light is the most commo ...

, but while the image on the left, which is a mirage, demonstrates only vertical distortion, the image on the right demonstrates distortion in all the ways possible. It is easier to see the vertical direction of the mirage not even at the mirage of the

itself, but rather at the mirage of a

sunspot Sunspots are temporary spots on the Sun's surface that are darker than the surrounding area. They are one of the most recognizable Solar phenomena and despite the fact that they are mostly visible in the solar photosphere they usually aff ...

. As a matter of fact, it is at least a three-image mirage of a sunspot, and all these images show a clear vertical direction. Sunspot Mirage

Inferior mirage of astronomical objects

Inferior mirage of

s is the most common mirage. Inferior mirage occurs when the surface of the

Earth Earth is the third planet from the Sun and the only astronomical object known to Planetary habitability, harbor life. This is enabled by Earth being an ocean world, the only one in the Solar System sustaining liquid surface water. Almost all ...

or the

ocean The ocean is the body of salt water that covers approximately 70.8% of Earth. The ocean is conventionally divided into large bodies of water, which are also referred to as ''oceans'' (the Pacific, Atlantic, Indian Ocean, Indian, Southern Ocean ...

s produces a layer of hot air of lower density, just at the surface. There are two images, the inverted one and the erect one, in inferior mirage. They both are displaced from the geometric direction to the actual object. While the erect image is setting, the inverted image appears to be rising from the surface. The shapes of inferior mirage sunsets and sunrises stay the same for all inferior mirage sunsets and sunrises. One well-known shape, the Etruscan vase, was named by

Jules Verne Jules Gabriel Verne (;''Longman Pronunciation Dictionary''. ; 8 February 1828 – 24 March 1905) was a French novelist, poet and playwright. His collaboration with the publisher Pierre-Jules Hetzel led to the creation of the ''Voyages extraor ...

. As the sunset progresses the shape of Etruscan vase slowly changes; the stem of the vase gets shorter until the real and the miraged Suns create a new shape – Greek letter omega Ω. The inferior mirage got its name because the inverted image appears below the erect one.An Introduction to Mirages
by Andy Young Here's how Jules Verne describes an inferior mirage

. : On very rare occasions the mirages of astronomical objects other than the

and the

might be observed. An

apparent magnitude Apparent magnitude () is a measure of the Irradiance, brightness of a star, astronomical object or other celestial objects like artificial satellites. Its value depends on its intrinsic luminosity, its distance, and any extinction (astronomy), ...

of an

should be low enough (that is, bright enough) in order to see it as not only a real object, but also a miraged one.

Mock mirage of astronomical objects

A mock mirage of

s is much more complex than an inferior mirage. While an inferior mirage of astronomical objects can produce only two images, a mock mirage can produce multiple miraged images. The shapes of the miraged object are changing constantly and unpredictably. In order for a mock mirage to appear, the cooler air needs to be trapped below the inversion. Several inversion layers produce multiple pancake-like shapes.Sunset Mirages
Les Cowley It is possible that the

solar Solar may refer to: Astronomy * Of or relating to the Sun ** Solar telescope, a special purpose telescope used to observe the Sun ** A device that utilizes solar energy (e.g. "solar panels") ** Solar calendar, a calendar whose dates indicate t ...

anomaly mentioned in the

Book of Joshua The Book of Joshua is the sixth book in the Hebrew Bible and the Old Testament, and is the first book of the Deuteronomistic history, the story of Israel from the conquest of Canaan to the Babylonian captivity, Babylonian exile. It tells of the ...

may have been an example of a mock mirage. In that tale, Joshua launched a surprise attack on the

Amorites The Amorites () were an ancient Northwest Semitic languages, Northwest Semitic-speaking Bronze Age people from the Levant. Initially appearing in Sumerian records c. 2500 BC, they expanded and ruled most of the Levant, Mesopotamia and parts of Eg ...

following a night march, causing the

to panic and flee as far as Beth-horon, but they did not find a safe haven there. "...they were more who died with the hailstones than they whom the children of Israel slew with the sword."The Book of Joshua 10.11
Joshua

Hail Hail is a form of solid Precipitation (meteorology), precipitation. It is distinct from ice pellets (American English "sleet"), though the two are often confused. It consists of balls or irregular lumps of ice, each of which is called a hailsto ...

stones are a rare event in

desert A desert is a landscape where little precipitation occurs and, consequently, living conditions create unique biomes and ecosystems. The lack of vegetation exposes the unprotected surface of the ground to denudation. About one-third of the la ...

s and are a good precondition for creating a mock/superior mirage of the setting

sun The Sun is the star at the centre of the Solar System. It is a massive, nearly perfect sphere of hot plasma, heated to incandescence by nuclear fusion reactions in its core, radiating the energy from its surface mainly as visible light a ...

. Inferior mirage is the most common mirage in the

s. When the Israelites went from a hot desert to a hail-covered desert to fight the Amorites, the inversion layers could have created a mock mirage of the setting sun. To the Israelites, the sun would then have appeared to stand still. A poem is quoted from the Book of Jasher, which states that the

stood still at Gibeon, and the

in the valley of Ajalon, in order that Joshua could complete the battle.The Book of Joshua 10.13
Joshua

Novaya Zemlya effect

Due to a normal

, sunrise occurs shortly before the Sun crosses above the horizon. Light from the Sun is bent, or refracted, as it enters Earth's atmosphere. This effect causes the apparent sunrise to be earlier than the actual sunrise. Similarly, apparent sunset occurs slightly later than actual sunset. In ordinary atmospheric conditions, the setting or rising Sun appears to be about half a degree above its geometric position. But sometimes, very unusual atmospheric circumstances can make it to be visible when it is really between two and five degrees below the horizon. This is called the

Novaya Zemlya effect The Novaya Zemlya effect is a polar mirage caused by high refraction of sunlight between atmospheric thermal layers. The effect gives the impression that the sun is rising earlier than it actually should, and depending on the meteorological si ...

, because it was first observed in

Novaya Zemlya Novaya Zemlya (, also , ; , ; ), also spelled , is an archipelago in northern Russia. It is situated in the Arctic Ocean, in the extreme northeast of Europe, with Cape Flissingsky, on the northern island, considered the extreme points of Europe ...

, where the Sun was seen when, according to astronomical calculations, it should have been two degrees below the horizon. However, due to changes in air pressure, relative humidity, and other quantities, the exact effects of atmospheric refraction on sunrise and sunset time cannot be predicted. Also note that this possible error increases with higher (closer to the poles) latitudes. Novaya Zemlya is a

polar region The polar regions, also called the frigid zones or polar zones, of Earth are Earth's polar ice caps, the regions of the planet that surround its geographical poles (the North and South Poles), lying within the polar circles. These high latitu ...

Russia Russia, or the Russian Federation, is a country spanning Eastern Europe and North Asia. It is the list of countries and dependencies by area, largest country in the world, and extends across Time in Russia, eleven time zones, sharing Borders ...

. The Novaya Zemlya effect is a

caused by high

sunlight Sunlight is the portion of the electromagnetic radiation which is emitted by the Sun (i.e. solar radiation) and received by the Earth, in particular the visible spectrum, visible light perceptible to the human eye as well as invisible infrare ...

between atmospheric

thermocline A thermocline (also known as the thermal layer or the metalimnion in lakes) is a distinct layer based on temperature within a large body of fluid (e.g. water, as in an ocean or lake; or air, e.g. an atmosphere) with a high gradient of distinct te ...

s. The Novaya Zemlya effect will give the impression that the sun is rising earlier than it actually should or the sun is setting later than it actually should.

Fridtjof Nansen Fridtjof Wedel-Jarlsberg Nansen (; 10 October 1861 – 13 May 1930) was a Norwegian polymath and Nobel Peace Prize laureate. He gained prominence at various points in his life as an explorer, scientist, diplomat, humanitarian and co-founded the ...

wrote It is possible to observe the Novaya Zemlya effect in any place, where the temperature variations are great enough to produce a high

Green flash

Green flash is a rare

that occurs during or shortly after set and during or before rise of a bright

, when a

green Green is the color between cyan and yellow on the visible spectrum. It is evoked by light which has a dominant wavelength of roughly 495570 nm. In subtractive color systems, used in painting and color printing, it is created by a com ...

spot is visible for a short period of

time Time is the continuous progression of existence that occurs in an apparently irreversible process, irreversible succession from the past, through the present, and into the future. It is a component quantity of various measurements used to sequ ...

above a mirage of an

or its set/rise point. Green flashes are enhanced by atmospheric inversions which increase the density gradient in the atmosphere, and therefore increase refraction. In other words, to see a green flash a mirage should be present.Explaining Green Flashes
by Andy Young

described a green flash. Many tend to believe that seeing a green flash brings good luck.K. Solarino : The Green Flash Collection Green flashes might be observed from any place with a low

horizon The horizon is the apparent curve that separates the surface of a celestial body from its sky when viewed from the perspective of an observer on or near the surface of the relevant body. This curve divides all viewing directions based on whethe ...

Desert A desert is a landscape where little precipitation occurs and, consequently, living conditions create unique biomes and ecosystems. The lack of vegetation exposes the unprotected surface of the ground to denudation. About one-third of the la ...

s and

ice shelves An ice shelf is a large platform of glacial ice floating on the ocean, fed by one or multiple tributary glaciers. Ice shelves form along coastlines where the ice thickness is insufficient to Displacement (fluid), displace the more dense surround ...

are probably the best places to observe mirages and therefore green flashes. It is easier not to miss a green flash during

than during

. It is especially true regarding an inferior mirage green flash, when the timing should be just right to capture it at sunrise. From the above observation it is clear that the author observed an inferior mirage green flash, when the much warmer surface of the

with the help of the rising Sun was fighting the cool morning air, producing in the process a green flash – one of nature's great spectacles. A green flash might be also seen with
rising or setting Moon.
br> In the right conditions it is common to observe multiple green flashes during one mock mirage sunset.
Some claim they saw a green flash from

Venus Venus is the second planet from the Sun. It is often called Earth's "twin" or "sister" planet for having almost the same size and mass, and the closest orbit to Earth's. While both are rocky planets, Venus has an atmosphere much thicker ...

. This may be true, but it might be that a color of the setting or the rising

is mistaken for a real green flash that is a by-product of a

Green rim

As an

sets or rises, the light it emits travels through the

atmosphere An atmosphere () is a layer of gases that envelop an astronomical object, held in place by the gravity of the object. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A stellar atmosph ...

, which works as a

prism PRISM is a code name for a program under which the United States National Security Agency (NSA) collects internet communications from various U.S. internet companies. The program is also known by the SIGAD . PRISM collects stored internet ...

separating the light into different colors. The color of the upper limb of an astronomical object could go from blue to green to violet depending on the decrease in concentration of pollutants as they spread throughout an increasing volume of atmosphere. The lower limb of an astronomical object is always red. The green rim is very thin, and is difficult or impossible to see with the

naked eye Naked eye, also called bare eye or unaided eye, is the practice of engaging in visual perception unaided by a magnification, magnifying, Optical telescope#Light-gathering power, light-collecting optical instrument, such as a telescope or microsc ...

. In usual conditions a green rim of an astronomical object gets fainter, when an astronomical object is very low above the

because of atmospheric reddening, but sometimes the conditions are right to see a green rim just above the horizon. The following quote describes probably the longest observation of a green rim, which sometimes could have been a green flash. Members of Richard E. Byrd's party from the Little America exploration base saw the phenomenon on and off for 35 minutes ^{(source for 30 versus 35 minutes?)}. Green rim and green flashes in SF

Often the green rim of the setting Sun will change to a green flash and then back again to a green rim during the same sunset. The image to the right might accurately illustrate what members of Byrd's party from the Little America base might have seen. However, to see a green rim and green flash on and off for 35 minutes, there must have been some degree of mirage present. A green rim is present in every sunset, but it is too thin to be seen with a naked

eye An eye is a sensory organ that allows an organism to perceive visual information. It detects light and converts it into electro-chemical impulses in neurons (neurones). It is part of an organism's visual system. In higher organisms, the ey ...

. The best time to observe the green rim is about 10 minutes before sunset time. However, the solar disc is too bright at that time to use

magnification Magnification is the process of enlarging the apparent size, not physical size, of something. This enlargement is quantified by a size ratio called optical magnification. When this number is less than one, it refers to a reduction in size, so ...

, such as

binoculars Binoculars or field glasses are two refracting telescopes mounted side-by-side and aligned to point in the same direction, allowing the viewer to use both eyes (binocular vision) when viewing distant objects. Most binoculars are sized to be held ...

telescope A telescope is a device used to observe distant objects by their emission, Absorption (electromagnetic radiation), absorption, or Reflection (physics), reflection of electromagnetic radiation. Originally, it was an optical instrument using len ...

s, to look directly at the Sun. Of course, a telescope or binoculars image can be projected on a sheet of paper for viewing. When the Sun gets closer to the horizon, the green rim gets fainter because of atmospheric reddening. Although a green rim is present in every sunset, and a green flash is rare because it requires a mirage to be present, it is actually more common for people to have seen a green flash rather than a green rim.

Not a mirage

The composite image on the left is made out of five frames of different

s. None of the images is a mirage. Frames # 1 and # 2 could fool even a very experienced observer. They do look like a mock mirage of the setting

, but they are not. Frames #3 and # 4 are clearly not a mirage. Frame # 5 is not a mirage and not even a

, it is a

spider Spiders (order (biology), order Araneae) are air-breathing arthropods that have eight limbs, chelicerae with fangs generally able to inject venom, and spinnerets that extrude spider silk, silk. They are the largest order of arachnids and ran ...

with the Sun as a background. The strange shapes of the Sun in this composite is due to vog and

cloud In meteorology, a cloud is an aerosol consisting of a visible mass of miniature liquid droplets, frozen crystals, or other particles, suspended in the atmosphere of a planetary body or similar space. Water or various other chemicals may ...

s. Numerous

atmospheric An atmosphere () is a layer of gases that envelop an astronomical object, held in place by the gravity of the object. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A stellar atmosphere ...

effects, such as vog,

clouds In meteorology, a cloud is an aerosol consisting of a visible mass of miniature liquid droplets, frozen crystals, or other particles, suspended in the atmosphere of a planetary body or similar space. Water or various other chemicals may c ...

smoke Smoke is an aerosol (a suspension of airborne particulates and gases) emitted when a material undergoes combustion or pyrolysis, together with the quantity of air that is entrained or otherwise mixed into the mass. It is commonly an unwante ...

smog Smog, or smoke fog, is a type of intense air pollution. The word "smog" was coined in the early 20th century, and is a portmanteau of the words ''smoke'' and ''fog'' to refer to smoky fog due to its opacity, and odour. The word was then inte ...

and others could generate a mirage like appearance of an

Lens flare A lens flare happens when light is scattered, or ''flared'', in a lens system, often in response to a bright light, producing a sometimes undesirable artifact in the image. This happens through light scattered by the imaging mechanism itself, ...

s and ghost images also might be responsible for a false mirage or a false green flash.

References

External links

All kind of mirages explained
Andrew T. Young's page with comprehensive explanations and simulations.

Andrew T. Young's page with comprehensive explanations and simulations.

explanations and image gallery, Les Cowley's Atmospheric Optics site.

Gallery

Image:Mock mirage sunset and brown pelicans.jpg, Mock mirage sunset with brown pelicans Image:Boiling sun new.gif, "Boiling" sun sunset Image:Sunset Mirage 03.jpg, Mock mirage sunset Image:Sunset mirage1231.JPG, Mock mirage sunset Image:Sunset mirage.jpg, Mock mirage sunset Image:GreenFlash.jpg, Mock mirage sunset with green flash Image:Mock mirage of the setting sun.jpg, Mock mirage sunset Image:Inferior mirage green flash.jpg,

Farallon Islands The Farallon Islands ( ), or Farallones (), are a group of islands and sea stacks in the Gulf of the Farallones, off the coast of San Francisco, California, United States. The islands are also sometimes referred to by mariners as the Devil's ...

and Inferior mirage green flash Image:Multiple green flashes on 101508.jpg, Sunset sequence with multiple green flashes {{DEFAULTSORT:Mirage Of Astronomical Objects Atmospheric optical phenomena