Even people far from astronomy know that stars have different brilliance. The brightest stars are easily visible in overexposed urban skies, while the faintest stars are barely visible under ideal viewing conditions.

To characterize the brightness of stars and other celestial bodies (for example, planets, meteors, the Sun and the Moon), scientists have developed a scale of stellar magnitudes.

Apparent magnitude(m; often referred to simply as "magnitude") indicates the radiation flux near the observer, i.e., the observed brightness of a celestial source, which depends not only on the actual radiation power of the object, but also on the distance to it.

This is a dimensionless astronomical quantity that characterizes the illumination created by a celestial object near the observer.

illumination- light quantity, equal to the ratio of the luminous flux incident on a small surface area to its area.
The unit of illumination in the International System of Units (SI) is the lux (1 lux = 1 lumen per square meter), in the CGS (centimeter-gram-second) - phot (one phot is equal to 10,000 lux).

Illumination is directly proportional to the light intensity of the light source. As the source moves away from the illuminated surface, its illumination decreases in inverse proportion to the square of the distance (the inverse square law).

The subjectively visible stellar magnitude is perceived as brilliance (for point sources) or brightness (for extended ones).

In this case, the brightness of one source is indicated by comparing it with the brightness of another, taken as a standard. Such standards are usually specially selected non-variable stars.

The magnitude was first introduced as an indicator of the apparent brightness of stars in the optical range, but later extended to other radiation ranges: infrared, ultraviolet.

Thus, the apparent stellar magnitude m or brilliance is a measure of the illumination E created by a source on a surface perpendicular to its rays at the place of observation.

Historically, it all began over 2000 years ago, when the ancient Greek astronomer and mathematician Hipparchus(II century BC) divided the stars visible to the eye into 6 magnitudes.

Hipparchus assigned the brightest stars the first magnitude, and the dimmest, barely visible to the eye, the sixth, and evenly distributed the rest among intermediate magnitudes. Moreover, Hipparchus made the division into magnitudes in such a way that the stars of the 1st magnitude seemed as brighter than the stars of the 2nd magnitude as they seem brighter than the stars of the 3rd magnitude, etc. That is, from gradation to gradation, the brightness of the stars changed by one and the same size.

As it turned out later, the relationship of such a scale with real physical quantities is logarithmic, since a change in brightness by the same number of times is perceived by the eye as a change by the same amount - empirical psychophysiological Weber-Fechner law, according to which the intensity of sensation is directly proportional to the logarithm of the intensity of the stimulus.

This is due to the peculiarities of human perception, for example, if 1, 2, 4, 8, 16 identical light bulbs are sequentially lit in a chandelier, then it seems to us that the illumination in the room increases by the same amount all the time. That is, the number of bulbs to be turned on should increase by the same number of times (in the example, twice) so that it seems to us that the increase in brightness is constant.

The logarithmic dependence of the strength of sensation E on the physical intensity of the stimulus P is expressed by the formula:

E = k log P + a, (1)

where k and a are some constants determined by a given sensory system.

In the middle of the 19th century English astronomer Norman Pogson formalized the scale of stellar magnitudes, which took into account the psychophysiological law of vision.

Based on actual observations, he postulated that

A STAR OF THE FIRST MAGNITUDE IS EXACTLY 100 TIMES BRIGHTER THAN A STAR OF THE SIXTH VALUE.

In this case, in accordance with expression (1), the apparent stellar magnitude is determined by the equality:

m = -2.5 lg E + a, (2)

2.5 - Pogson coefficient, minus sign - a tribute to historical tradition (brighter stars have a smaller, including negative, magnitude);
a is the zero point of the stellar magnitude scale, established by an international agreement related to the choice of the base point of the measuring scale.

If E 1 and E 2 correspond to the stellar magnitudes m 1 and m 2, then from (2) it follows that:

E 2 /E 1 \u003d 10 0.4 (m 1 - m 2) (3)

A decrease in magnitude by one m1 - m2 = 1 leads to an increase in illumination E by about 2.512 times. When m 1 - m 2 = 5, which corresponds to the range from the 1st to the 6th magnitude, the change in illumination will be E 2 /E 1 =100.

Pogson's formula in its classical form establishes a relationship between apparent stellar magnitudes:

m 2 - m 1 \u003d -2.5 (lgE 2 - lgE 1) (4)

This formula allows you to determine the difference in stellar magnitudes, but not the magnitudes themselves.

To use it to construct an absolute scale, it is necessary to set zero point is the brightness corresponding to zero magnitude (0 m). First, the brightness of Vega was taken as 0 m. Then the zero point was redefined, but for visual observations Vega can still serve as a standard of zero apparent stellar magnitude (according to the modern system, in the V band of the UBV system, its brightness is +0.03 m, which is indistinguishable from zero by eye).

Usually, however, the zero-point of the magnitude scale is conventionally taken from the totality of stars whose careful photometry has been carried out by various methods.

Also, for 0 m, a well-defined illumination is taken, equal to the energy value E \u003d 2.48 * 10 -8 W / m². Actually, it is the illumination that astronomers determine during observations, and only then it is specially translated into stellar magnitudes.

They do this not only because “it’s more familiar,” but also because the magnitude turned out to be a very convenient concept.

magnitude turned out to be a very convenient concept

Measuring illumination in watts per square meter is extremely cumbersome: for the Sun, the value is large, and for faint telescopic stars, it is very small. At the same time, it is much easier to operate with magnitudes, since the logarithmic scale is extremely convenient for displaying very large ranges of magnitude values.

Pogson's formalization subsequently became the standard method for estimating magnitudes.

True, the modern scale is no longer limited to six magnitudes or only visible light. Very bright objects can have a negative magnitude. For example, Sirius, the brightest star in the celestial sphere, has a magnitude of minus 1.47m. The modern scale also allows you to get the value for the Moon and the Sun: the full moon has a magnitude of -12.6 m, and the Sun -26.8 m. The Hubble Orbiting Telescope can observe objects whose brightness is up to about 31.5 m.

magnitude scale
(the scale is reversed: smaller values ​​correspond to brighter objects)

Apparent stellar magnitudes of some celestial bodies

Sun: -26.73
Moon (full moon): -12.74
Venus (at maximum brightness): -4.67
Jupiter (at maximum brightness): -2.91
Sirius: -1.44
Vega: 0.03
Faintest stars visible to the naked eye: about 6.0
Sun from 100 light years away: 7.30
Proxima Centauri: 11.05
Brightest quasar: 12.9
Faintest objects photographed by the Hubble Space Telescope: 31.5

We are talking about someone who has achieved certain heights in his business, has reached the highest stage of success in some field. Origin of expression first magnitude star is a direct comparison with the classification of astronomical objects.

In the starry sky, it can be seen with the naked eye that the stars differ in their brightness, that is, in their apparent brilliance. This includes the notion of visible magnitude, which was first described and classified by the ancient Greek astronomer Hipparchus in the 2nd century BC. e. Magnitude- dimensionless numerical characteristic of the brightness of the object. Hipparchus divided everything stars for six quantities. He named the brightest stars of the first magnitude, the dimmest - stars of the sixth magnitude. Intermediate values ​​he distributed evenly among the remaining stars.

Later, based on the writings of Hipparchus and his own studies of the starry sky, Ptolemy compiled a star catalog that scientists and astronomers used for more than a thousand years. In it, Ptolemy left the classification of Hipparchus regarding stellar brightness, classifying stars according to the brightness of the glow, that is, according to the apparent brilliance. The visible brightness does not carry any other characteristics of a particular star, because it depends not so much on the size of the star itself, but on the distance of the star from the Earth and on some other optical parameters.

Applied to people, the expression first magnitude star describes a person as figure of the first magnitude in his business, with his branch of knowledge, art, etc. And the word star in this characteristic emphasizes the brilliant abilities or knowledge of this person.

Other interesting expressions from Russian speech:

To know by heart - this expression is familiar to everyone from school. Know on

The expression tooth for tooth is quite simple and clear, like Newton's third law. Means

One of the main versions of the origin of the expression If the mountain does not go to Mohammed,

Expression There is life in the old dog yet with a high degree of probability went

One more, last tale, and my chronicle is over...

Star of the first magnitude Rapture. A person who has become famous in any field of knowledge, activity. - Before the Maly Theater, Medvedeva has another merit, not only as an artist: everyone in the history of the theater knows that Medvedev discovered, guessed and gave the theater a star of the first magnitude - Yermolov(T. Shchepkina-Kupernik. Theater in my life).

Phraseological dictionary of the Russian literary language. - M.: Astrel, AST. A. I. Fedorov. 2008 .

See what the "Star of the First Magnitude" is in other dictionaries:

first magnitude star- See glorious ... Dictionary of Russian synonyms and expressions similar in meaning. under. ed. N. Abramova, M .: Russian dictionaries, 1999. star of the first magnitude n., number of synonyms: 9 ... Synonym dictionary

Star of the first magnitude- Borrowed from astronomy. Even in the first astronomical catalogs of the ancient Greek scientists Hyparchus (II century BC) and Claudius Ptolemy (c. 90 c. 160), all the stars visible to the eye were divided into six "magnitudes" according to the degree of brightness. Respectively… … Dictionary of winged words and expressions

Star of the first magnitude- Book. OK, Shuttle. or Iron. About an outstanding figure, master, specialist in what field. areas. FSRYA, 172; BMS 1998, 204 ...

star- See the famous, glorious, fate is far away, as to a heavenly star, a guiding star ... Dictionary of Russian synonyms and expressions similar in meaning. under. ed. N. Abramova, M .: Russian dictionaries, 1999. star (celestial) luminary, asterisk, beacon of the universe, ... ... Synonym dictionary

star- s, pl. stars, w. 1. A celestial body consisting of hot gases (plasma), similar in nature to the Sun and appearing to the human eye in the night sky as a luminous dot. Polar Star. Evening Star. □ The air was fresh and… … Small Academic Dictionary

star- s, wine.; y/; pl. stars, stars, stars; well. see also stellar, asterisk 1) a) A self-luminous celestial body, similar in nature to the Sun and visible in the night sky as a bright point. Polar Star/. Cluster of stars... Dictionary of many expressions

STAR- To the white stars. Pribaik. Long, late. SNFP, 70. There are not enough stars from the sky. Razg. Iron. or Neglect. About a narrow-minded, incapable, untalented person. FSRYA, 172; BMS 1998, 204; BTS, 1440. Grab the stars. Bashk. About stains on clothes. SRGB 1,… … Big dictionary of Russian sayings

Star- uh, wine. y; pl. stars, stars, stars; well. 1. Self-luminous celestial body, similar in nature to the Sun and visible in the night sky as a bright point. Polyarnaya Z. Cluster of stars. The glow of the stars. The stars light up, shine, twinkle. The stars of the first, ... ... encyclopedic Dictionary

STAR- STAR, s, pl. stars, stars, am, wives. 1. Celestial body (hot gas ball), visible at night as a luminous dot. The stars lit up. Sky in the stars. Polyarnaya Z. Z. of the first magnitude (the brightest, as well as translation: about an outstanding artist, ... ... Explanatory dictionary of Ozhegov

Wolf Star - Rayet- Artistic depiction of Wolf Rayet's star Wolf Rayet's stars are a class of stars that are characterized by very high temperature and luminosity; Wolf Rayet stars differ from other hot stars in the presence of wide hydrogen emission bands in the spectrum ... Wikipedia

Books

• Supporting star, Georgy Lanskoy. Marina came to Moscow to pursue a musical career. It is not easy to break through in the capital, but the stubborn provincial does not give up and is ready to gnaw her way to glory with her teeth. Moreover, in front of her ...