Ashen light
Encyclopedia
Ashen light is a subtle glow that is seen from the night side of the planet Venus
. This ashen light is said to be very similar to Earthshine on our moon
, but not as distinguished in brightness. It was first sighted by the astronomer Giovanni Battista Riccioli
on January 9, 1643, and has been frequently sighted by various researchers including Sir William Herschel, Patrick Moore
, Dale P. Cruikshank, and William K. Hartmann.
Before the development of more powerful telescopes, early astronomer Franz von Gruithuisen
believed that ashen light was from the fires from celebration of a new Venusian emperor, and later believed that it was the inhabitants burning vegetation to make room for farmland.
have been dedicated to record sightings of the light in hopes of solidifying what Riccioli and others have claimed. There are a few hypotheses being considered to try to explain this astronomical phenomenon.
An attempt to view the ashen light was made in Hawaii
using the Keck 1 telescope. Researchers claimed to see a faint green glow on the night side of Venus. They suspected that is was carbon dioxide
which is known be of a high concentration in that atmosphere. When the molecules are split by the ultraviolet light from the Sun, they become carbon monoxide
and oxygen
, which emits a green light. However, this light emitted is very faint, and researchers doubt that it is the explanation surrounding ashen light.
Few other optical observations have been recorded with current instruments. For example, the spectrometer of Venera 9 saw irregular optical pulses.
Amateur astronomers
attempting to view the ashen light can try this by using an occulting bar, an opaque mask for one’s eyes. This lens blocks the sunlit portion of Venus which greatly cuts down extraneous light that is scattered in the eye, improving the chances of witnessing the faint Ashen glow. However, Venus light scattered by the Earth's atmosphere and in the telescope's lens still works against the observer, and it is very hard to get the timing just right. Nevertheless, there have been calculated times in which the light scattered by Earth is covered partially by our Moon. For example, on July 17, 2001, the progression of a crescent
Moon temporarily hid the illuminated portion of Venus. Unfortunately the location needed to catch this almost perfect occultation was somewhere in the middle of the Atlantic Ocean
, and it was only visible in this manner for 10 to 20 seconds.
. If there are several strikes in a period of time, the sequence may give off an overall glow in the skies of Venus, if this happens on the night side. However, in an article published in the January issue of Nature
, a team of astronomers from the University of Iowa expressed negative criticism and doubt of this idea. After reviewing data taken from the Cassini spacecraft, which flew close to Venus in 1998 and 1999, the team resolved that no high-frequency radio noise was detected. On Earth we hear "static"-like noise on AM radio stations during thunderstorms. If the light was caused by lightning, similar noise would have been expected. In 2007, whistler waves
were detected by Venus Express
, confirming the occurrence of lightning on Venus. This seems to be the most promising hypothesis, supported by many astronomers, including two researchers whose paper on their findings is examined below.
and J. L. Phillips from the Institute of Geophysics and Planetary Physics at the University of California in Los Angeles and the Los Alamos National Laboratory
in Los Alamos, New Mexico
have offered a mathematical approach to figuring out how exactly the ashen light is formed. The favored hypothesis, as explained in the paper, is the idea of lightning on Venus. Both believe that the phenomenon has occurred, stating in their paper that:
Taking into consideration the limited amount of observation and the “simplicity of the model”, according to Russell and Phillips, the relation between observed sightings and the calculation seems to bring more promise in finding out the true cause of ashen light. It supports the hypothesis that the source of ashen light occurs mostly on the night side of Venus. The distance from the Earth to Venus could be a factor that controls the visibility of the light, however it also has to do with the observer’s specific location.
Venus
Venus is the second planet from the Sun, orbiting it every 224.7 Earth days. The planet is named after Venus, the Roman goddess of love and beauty. After the Moon, it is the brightest natural object in the night sky, reaching an apparent magnitude of −4.6, bright enough to cast shadows...
. This ashen light is said to be very similar to Earthshine on our moon
Moon
The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...
, but not as distinguished in brightness. It was first sighted by the astronomer Giovanni Battista Riccioli
Giovanni Battista Riccioli
Giovanni Battista Riccioli was an Italian astronomer and a Catholic priest in the Jesuit order...
on January 9, 1643, and has been frequently sighted by various researchers including Sir William Herschel, Patrick Moore
Patrick Moore
Sir Patrick Alfred Caldwell-Moore, CBE, FRS, FRAS is a British amateur astronomer who has attained prominent status in astronomy as a writer, researcher, radio commentator and television presenter of the subject, and who is credited as having done more than any other person to raise the profile of...
, Dale P. Cruikshank, and William K. Hartmann.
Before the development of more powerful telescopes, early astronomer Franz von Gruithuisen
Franz von Gruithuisen
Baron Franz von Paula Gruithuisen was a Bavarian physician and astronomer. He taught medical students before becoming a professor of astronomy at the University of Munich in 1826....
believed that ashen light was from the fires from celebration of a new Venusian emperor, and later believed that it was the inhabitants burning vegetation to make room for farmland.
Detection attempts
Several space missionsSpace exploration
Space exploration is the use of space technology to explore outer space. Physical exploration of space is conducted both by human spaceflights and by robotic spacecraft....
have been dedicated to record sightings of the light in hopes of solidifying what Riccioli and others have claimed. There are a few hypotheses being considered to try to explain this astronomical phenomenon.
An attempt to view the ashen light was made in Hawaii
Hawaii
Hawaii is the newest of the 50 U.S. states , and is the only U.S. state made up entirely of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean, southwest of the continental United States, southeast of Japan, and northeast of...
using the Keck 1 telescope. Researchers claimed to see a faint green glow on the night side of Venus. They suspected that is was carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
which is known be of a high concentration in that atmosphere. When the molecules are split by the ultraviolet light from the Sun, they become carbon monoxide
Carbon monoxide
Carbon monoxide , also called carbonous oxide, is a colorless, odorless, and tasteless gas that is slightly lighter than air. It is highly toxic to humans and animals in higher quantities, although it is also produced in normal animal metabolism in low quantities, and is thought to have some normal...
and oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
, which emits a green light. However, this light emitted is very faint, and researchers doubt that it is the explanation surrounding ashen light.
Few other optical observations have been recorded with current instruments. For example, the spectrometer of Venera 9 saw irregular optical pulses.
Amateur astronomers
Amateur astronomy
Amateur astronomy, also called backyard astronomy and stargazing, is a hobby whose participants enjoy watching the night sky , and the plethora of objects found in it, mainly with portable telescopes and binoculars...
attempting to view the ashen light can try this by using an occulting bar, an opaque mask for one’s eyes. This lens blocks the sunlit portion of Venus which greatly cuts down extraneous light that is scattered in the eye, improving the chances of witnessing the faint Ashen glow. However, Venus light scattered by the Earth's atmosphere and in the telescope's lens still works against the observer, and it is very hard to get the timing just right. Nevertheless, there have been calculated times in which the light scattered by Earth is covered partially by our Moon. For example, on July 17, 2001, the progression of a crescent
Crescent
In art and symbolism, a crescent is generally the shape produced when a circular disk has a segment of another circle removed from its edge, so that what remains is a shape enclosed by two circular arcs of different diameters which intersect at two points .In astronomy, a crescent...
Moon temporarily hid the illuminated portion of Venus. Unfortunately the location needed to catch this almost perfect occultation was somewhere in the middle of the Atlantic Ocean
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...
, and it was only visible in this manner for 10 to 20 seconds.
Other hypotheses
Another hypothesis for the cause of the ashen light is lightningLightning
Lightning is an atmospheric electrostatic discharge accompanied by thunder, which typically occurs during thunderstorms, and sometimes during volcanic eruptions or dust storms...
. If there are several strikes in a period of time, the sequence may give off an overall glow in the skies of Venus, if this happens on the night side. However, in an article published in the January issue of Nature
Nature
Nature, in the broadest sense, is equivalent to the natural world, physical world, or material world. "Nature" refers to the phenomena of the physical world, and also to life in general...
, a team of astronomers from the University of Iowa expressed negative criticism and doubt of this idea. After reviewing data taken from the Cassini spacecraft, which flew close to Venus in 1998 and 1999, the team resolved that no high-frequency radio noise was detected. On Earth we hear "static"-like noise on AM radio stations during thunderstorms. If the light was caused by lightning, similar noise would have been expected. In 2007, whistler waves
Whistler (radio)
A whistler is a very low frequency electromagnetic wave which can be generated, for example, by lightning. Frequencies of terrestrial whistlers are 1 to 30 kHz, with maximum usually at 3 to 5 kHz. Although they are electromagnetic waves, they occur at audio frequencies, and can be...
were detected by Venus Express
Venus Express
Venus Express is the first Venus exploration mission of the European Space Agency. Launched in November 2005, it arrived at Venus in April 2006 and has been continuously sending back science data from its polar orbit around Venus. Equipped with seven science instruments, the main objective of the...
, confirming the occurrence of lightning on Venus. This seems to be the most promising hypothesis, supported by many astronomers, including two researchers whose paper on their findings is examined below.
Russell and Phillips
Christopher T. RussellChristopher T. Russell
Christopher Thomas Russell is head of the Space Physics Center at the Institute of Geophysics and Planetary Physics at UCLA, professor in UCLA's Department of Earth and Space Sciences, and Director of the UCLA Branch of the California Space Grant Consortium. He received a B.Sc. from the...
and J. L. Phillips from the Institute of Geophysics and Planetary Physics at the University of California in Los Angeles and the Los Alamos National Laboratory
Los Alamos National Laboratory
Los Alamos National Laboratory is a United States Department of Energy national laboratory, managed and operated by Los Alamos National Security , located in Los Alamos, New Mexico...
in Los Alamos, New Mexico
Los Alamos, New Mexico
Los Alamos is a townsite and census-designated place in Los Alamos County, New Mexico, United States, built upon four mesas of the Pajarito Plateau and the adjoining White Rock Canyon. The population of the CDP was 12,019 at the 2010 Census. The townsite or "the hill" is one part of town while...
have offered a mathematical approach to figuring out how exactly the ashen light is formed. The favored hypothesis, as explained in the paper, is the idea of lightning on Venus. Both believe that the phenomenon has occurred, stating in their paper that:
Inferior vs. superior conjunction
Assuming that the location and the ability to observe the ashen light is in our favor, meaning we do not have to be in the middle of the ocean with technical instruments that allow us to view it without damage done to the eyes, Russell and Phillips found that it is possible to replicate the common characteristics of the sightings measured in the figure above. A more detailed explanation can be found in the paper itself for those interested in the mathematics of it.Taking into consideration the limited amount of observation and the “simplicity of the model”, according to Russell and Phillips, the relation between observed sightings and the calculation seems to bring more promise in finding out the true cause of ashen light. It supports the hypothesis that the source of ashen light occurs mostly on the night side of Venus. The distance from the Earth to Venus could be a factor that controls the visibility of the light, however it also has to do with the observer’s specific location.