The Antoniadi scale is a system used by amateur

astronomers An astronomer is a scientist in the field of astronomy who focuses their studies on a specific question or field outside the scope of Earth. They observe astronomical objects such as stars, planets, natural satellite, moons, comets and galaxy, g ...

to categorise the weather conditions when viewing the stars at night.

Invention

The Antoniadi scale was invented by

Eugène Antoniadi Eugène Michel Antoniadi (Greek: Ευγένιος Αντωνιάδης; 1 March 1870 – 10 February 1944) was a Greek-French astronomer. Biography Antoniadi was born in Istanbul (Constantinople) but spent most of his adult life in France ...

, a Greek astronomer, who lived from 1870 to 1944. Living most of his life in

France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...

, he spent his time viewing

Mars Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury (planet), Mercury. In the English language, Mars is named for the Mars (mythology), Roman god of war. Mars is a terr ...

from Camille Flammarion's observatory. He was very prestigious and was eventually given access to the

Meudon Observatory The Paris Observatory (french: Observatoire de Paris ), a research institution of the Paris Sciences et Lettres University, is the foremost astronomical observatory of France, and one of the largest astronomical centers in the world. Its histor ...

, the largest of the time.

Current usage

Now the scale considered as the metric system of

astronomical seeing In astronomy, seeing is the degradation of the image of an astronomical object due to turbulence in the atmosphere of Earth that may become visible as blurring, twinkling or variable distortion. The origin of this effect are rapidly changing v ...

, being used as a default measurement all over the world. Until recently in 2018, astronomers have been debating whether a new system with more categories is necessary.

Description

The scale is a five-point system, with 1 being the best seeing conditions and 5 being the worst. The actual definitions are as follows: # (I.) Perfect seeing, without a quiver. # (II.) Slight quivering of the image with moments of calm lasting several seconds. # (III.) Moderate seeing with larger air tremors that blur the image. # (IV.) Poor seeing, constant troublesome undulations of the image. # (V.) Very bad seeing, hardly stable enough to allow a rough sketch to be made. Note that the scale is usually indicated by use of a

Roman numeral Roman numerals are a numeral system that originated in ancient Rome and remained the usual way of writing numbers throughout Europe well into the Late Middle Ages. Numbers are written with combinations of letters from the Latin alphabet, eac ...

or an ordinary number.

Other ways of indicating seeing

Astronomers have devised several methods for defining the quality of seeing apart from the Antoniadi scale, including: * Transparency *

Limiting magnitude In astronomy, limiting magnitude is the faintest apparent magnitude of a celestial body that is detectable or detected by a given instrument. In some cases, limiting magnitude refers to the upper threshold of detection. In more formal uses, limi ...

* a

light meter A light meter is a device used to measure the amount of light. In photography, a light meter (more correctly an exposure meter) is used to determine the proper exposure for a photograph. The meter will include either a digital or analog calcul ...

References

External links

https://www.webcitation.org/5knIUG6ml?url=http://www.geocities.com/kev_woodward/seeingscale.htm archived 2009-10-25

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