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**"MAGNITUDE"****Related Terms:**Apparent magnitude, Absolute magnitude, Visual magnitude, Limiting magnitude, Absolute brightness, Apparent brightness, Standard candle, Richter magnitude scale, Spectroscopic parallax, Eclipsing binary, Fireball, Binary star, Richter scale, Milky way, Star, Sun, Bolometric magnitude, Zodiacal light, Mercalli scale, Variable star, Double star, Interstellar, Astronomical twilight, Gegenschein, Sirius, A.u, Dyson sphere, Stellar wind, Constellation, Light curve, Occultation, Modified mercalli intensity scale, Planet, Phase , Olber's paradox, Luminosity, Oort cloud, Terminator, Astrometry, Dark matter, Roche lobe, Radiant, Meteor shower, Brightness ratio, Meteor, Binary stars, Faculae, Nebula, Binary star system

Size. Magnitude being purely relative, nothing is large and nothing small. If everything in the universe were increased in bulk one thousand diameters nothing would be any larger than it was before, but if one thing remain unchanged all the others would be larger than they had been. To an understanding familiar with the relativity of magnitude and distance the spaces and masses of the astronomer would be no more impressive than those of the microscopist. For anything we know to the contrary, the visible universe may be a small part of an atom, with its component ions, floating in the life- fluid (luminiferous ether) of some animal. Possibly the wee creatures peopling the corpuscles of our own blood are overcome with the proper emotion when contemplating the unthinkable distance from one of these to another.

See magnitude of a star, below.

The strength or size of an event. Usually used when discussing earthquakes or hurricanes. seismic

A quantity characteristic of the total energy released by an earthquake, as contrasted with intensity, which describes its effects at a particular place. A number of earthquake magnitude scales exist, including local (or Richter) magnitude (ML), body wave magnitude (Mb), surface wave magnitude (Ms), moment magnitude (Mw), and coda magnitude (Mc). As a general rule, an increase of one magnitude unit corresponds to ten times greater ground motion, an increase of two magnitude units corresponds to 100 times greater ground motion, and so on in a logarithmic series. Commonly, earthquakes are recorded with magnitudes from 0 to 8, although occasionally large ones (M = 9) and very small ones (M = -I or -2) are also recorded. Nearby earthquakes with magnitudes as small as 2 to 3 are frequently felt. The actual ground motion for, say, a magnitude 5 earthquake is about 0.04 millimeters at a distance of 100 kilometers from the epicenter; it is 1.1 millimeters at a distance of 10 kilometers from the epicenter.

Astronomers use magnitudes to describe the brightness of an object in the sky. It is a non-linear, numerical scale where the smaller numbers represent brighter objects. Generally, the unaided eye can see stars down to magnitude 6 in good skies. Pluto is magnitude 14, and thus, is invisible without optical aid or photography. Venus has a magnitude of about -4 and the Sun is -27.

The brightness of stars and other celestial objects. Smaller numbers are brighter (negative numbers are the brightest). The scale assumes dark skies. Venus is -4.4, and the faintest star visible to the naked eye is about +6.0.

The apparent brightness of celestial objects. In ancient times the magnitude scale ran from 1 (the brightest stars) to 6 (the faintest star visible to the eye). Today magnitude has a precise meaning: a magnitude difference of 1 is equal to a brightness difference of 2.5. With this definition the magnitude scale includes all objects from the sun to the faintest stars which can be seen only in the largest telescopes.

A measure of earthquake size, determined by taking the common logarithm (base 10) of the largest ground motion observed during the arrival of a P wave or seismic surface wave and applying a standard correction for distance to the epicenter.

A scale used to compare the brightness of objects in the sky. One magnitude is a difference of 2.512 times in brightness.

A numerical expression of the amount of energy released by an earthquake, determined by measuring earthquake waves on standardized recording instruments (seismographs.) The number scale for magnitudes is logarithmic rather than arithmetic; therefore, deflections on a seismograph for a magnitude 5 earthquake, for example, are 10 times greater than those for a magnitude 4 earthquake, 100 times greater than for a magnitude 3 earthquake, and so on.

A measure of brightness, or faintness, as perceived by the human eye. In the system used by astronomers, the higher the magnitude, the fainter the object. The magnitude and apparent brightness of a star are related in a logarithmic fashion. For every five steps in magnitude, the apparent brightness of a star, galaxy, or nebula changes by a factor of 100. For example, we receive 100 times more light energy from Vega -- a zero-magnitude star -- than from Eta Ursa Minor -- a fifth-magnitude star in the Little Dipper. Under the clearest, darkest skies, your eye cannot see stars fainter than sixth magnitude. With the aid of binoculars, the human eye can detect 10th-magnitude stars.

a combination of the scale, extent and duration of an effect.

A measure of the brightness of a star. It is based on a system established by Hipparchus, in which stars were ranked according to how bright they appeared to the unaided eye. In the modern system, a difference of five magnitudes corresponds exactly to a brightness ratio of 100, so that a star of a given magnitude has a brightness that is 1001/5 = 2.51 times that of a star one magnitude fainter.

Brightness of a celestial body based on a logarithmic scale of intensity to which the eye naturally responds.

The degree of brightness of a celestial object designated on a numerical scale. The brightest star has magnitude -1.4 and the faintest star visible to the naked eye has magnitude of 5 or 6. Limiting magnitude refers to the faintest object visible without telescopic aid.

A measure of the size of an earthquake, determined by measuring the highest-amplitude waves and correcting for distance and type of instrument. The scale is logarithmic, so each increase of one unit corresponds to amplitude increase of a factor of 10.

measure that describes the strength or force of an event. The Richter Scale measures the magnitude of earthquakes through the amount of energy released. Magnitude is an important characteristic for analyzing hazards since only occurrences exceeding some defined level of magnitude are considered extreme, disastrous, or even hazardous.

A measure of earthquake strength based upon the amount of ground motion experienced and corrected for the distance between the observation point and the epicenter. There are several magnitude scales in use.

the total energy encompassed by the event; the combination of the integral of the amplitudes, the area involved (being studied), and total duration of the event.

A measure of the size of an earthquake, usually calculated from the common logarithm of the largest ground motion observed and corrected for distance from the earthquake focus.

One of the most important pieces of information gathered by amateur astronomers. This represents the estimated brightness of the comet when compared to stars around it. The term "m1" is used to represent the total or integrated brightness of the comet's coma, while "m2" represents the brightness of the nucleus. Observers estimate "m1" by usually memorizing the comet's appearance and then defocusing the surrounding stars to a size equivalent to the comet's coma diameter. The memorized comet's appearance is then compared to the defocused stars to determine the comet's brightness. In meteor astronomy the magnitude of a meteor is compared to that of other stars in the sky. The magnitude scale is set up so that the brighter magnitudes are actually represented by smaller numbers. The sun is about magnitude -26, the moon -12, Venus is -4, and the faintest naked-eye star is generally about +6.

The brightness of a stellar object, as ranked on a scale in which the brightest stars are first magnitude, meaning of the first order of importance, and fainter stars are second, third, or fainter magnitudes. If not prefixed by a descriptive limiter, usually presumed identical to apparent magnitude.

measure of total energy released by an earthquake. Contrast with intensity, which is measure of effects of earthquake waves at particular place. Several different magnitude scales are used: surface wave magnitude (Ms), body wave magnitude (mb), moment magnitude (Mw), local magnitude (Ml) and several others. See magnitude definitions for more information

A measure of the strength of an earthquake. There are several scales depending on which part of the seismogram is examined. These include Richter local magnitude (ML), Body wave magnitude (mb) and surface wave magnitude (Ms). Moment magnitude (Mw) is calculated from spectral analysis.

The brightness of a celestial body on a numerical scale. See also absolute magnitude, apparent magnitude, bolometric magnitude and integrated magnitude.

The magnitude scale is used to compare the brightness of celestial objects. Objects with smaller magnitudes are brighter. The star Vega was selected to define magnitude 0. Thus it is also possible to have negative magnitudes since the Sun, four stars, four planets, and Earth's moon all appear brighter than Vega. Sirius, for example, is the brightest star in the night sky at magnitude -1.46.

the power of an earthquake.

Astronomical measurement of the brightness of an object; the lower the number, the bright the object

The apparent brightness of an object. The lower the magnitude, the brighter the object, so magnitude 1 is brighter than magnitude 2, while magnitude -1 is brighter still. Sirius, the brightest star, has a magnitude of -1.4. The limit of naked eye visibility is about 6.

brightness scale; the smaller the magnitude number, the brighter the object so that the Sun (magnitude -26) is much brighter than Uranus (magnitude +6)

size The magnitude of the vector shows how big it is The mass of the nucleus is many orders of magntidue greater than that of the electrons in an atom. The magnitude of a star is a measure of how bright it is.

Magnitude is a measure of the amount of energy released during an earthquake. It may be expressed using the Richter scale. See: What is the "magnitude" of an earthquake? What it is the difference between magnitudes ML and mN? Certain earthquakes have a negative magnitude, is this an error? Is there a maximum magnitude for an earthquake? At what magnitude do earthquakes begin to be felt? When does damage start do to be observed? Do several magnitude scales exist

a logarithmic measure of flux apparent (m) calculated from received flux: for two stars 1 and 2, m1 - m2 = -2.5 log10(f1/f2) absolute (M) calculated for a standard distance of 10 pc: m - M = 5 log10(d/10) where d is the distance of the star in parsecs; for two stars 1 and 2, M1 - M2 = -2.5 log10(L1/L2)

Number that is scaled to the amount of energy released by an earthquake. An increase of one magnitude unit (for example, from 5 to 6) corresponds to a 10-fold increase in the amount of ground motion and an approximately 30-fold increase in the amount of energy produced by an earthquake.

The logarithmic scale used to quantify the brightness of celestial objects. Each change of five magnitudes is equivalent to a 100-fold change in brightness. Each change of one magnitude equals roughly a 2.52 change in brightness.

A measure of the apparent brightness of a celestial object.

An expression of the brightness of a star or other celestial object as it appears from Earth, according to a system devised by Hipparchus (190-120 B.C.). Also known as apparent magnitude to distinguish it from absolute magnitude. The larger the magnitude, the fainter the star. Brighter stars have smaller numbers, and the brightest stars and planets have negative magnitudes. One magnitude difference is equal to a brightness difference of 2.5 times.

The seismic (earthquake) energy recorded on a seismograph.

A measure of the total amount of energy released by an earthquake. more details....

The brightness of a celestial object as observed from earth. Originally the brightest stars were 1st magnitude and the faintest to the eye 6th magnitude. This resulted in a logarithmic ratio in which 5 magnitudes equaled a brightness of 100 fold. To accommodate brighter stars, it was necessary to invoke zero and negative values.

See Apparent magnitude, Absolute magnitude.

The method we use today to compare the apparent brightness (magnitude) of stars began with Hipparchus, a Greek astronomer who lived in the second century BC. Hipparchus called the brightest star in each constellation "first magnitude." Ptolemy, in 140 A.D., refined Hipparchus' system and used a 1 to 6 scale to compare star brightness, with 1 being the brightest and 6 the faintest. [More Info

The brightness of a celestial body, like a star. This is described in a scale where the brightest star, Sirius, is said to be "magnitude -1.4" (note: this is less than zero), and the faintest visible stars are said to be "magnitude 6". Note that the lower the number the brighter the star. A magnitude 1 star is 100 times brighter than a magnitude 6 star.

A measurement of the brightness of a star or other celestial object. On the magnitude scale, the lowest numbers refer to objects of greatest brightness.

A measure of the strength of an earthquake or strain energy released by it, as determined by seismographic observations. This is a logarithmic value originally defined by Charles Richter in 1935. An increase of one unit of magnitude (for example, from 4.6 to 5.6) represents a 10-fold increase in wave amplitude on a seismogram or approximately a 30-fold increase in the energy released. In other words, a magnitude 6.7 earthquake releases over 900 times (30 times 30) the energy of a 4.7 earthquake. There is no beginning nor end to this scale. However, rock mechanics seems to preclude earthquakes smaller than about -1 or larger than about 9.5. Except in special circumstances, earthquakes below magnitude 2.5 are not generally felt by humans.

The degree of brightness of a celestial body designated on a numerical scale, on which the brightest star has magnitude -1.4 and the faintest star visible to the unaided eye, has magnitude 6. A decrease of one unit represents an increase in apparent brightness by a factor of 2.512. Apparent magnitude of a star is the brightness as we see it from Earth, whilst absolute magnitude is a measure of its intrinsic luminosity. Lower numbers represent brighter objects.

A scale on which the brightness of a star is measured. This scale is logarithmic, meaning each successive magnitude is increasingly brighter/dimmer than the last. To be more precise, each change of five magnitudes is equivalent to a change by a factor of 100. Also, stars with a lower magnitude are the brightest. Stars may have negative magnitudes. For example, a star with a magnitude of -1 is 100 times brighter than one of a magnitude of 4. See also: Absoulte Magnitude, Absolute Visual Magnitude, and Apparent Magnitude.

A measure of the energy released by an earthquake. Measured using the Richter scale based on the amplitude of the seismic wave recorded by seismographs.

the measurement of an object's brightness; the lower the number, the brighter the object

a scale used by astronomers to measure flux. Each 5 units on the magnitude scale corresponds to a 100-fold decrease in the flux. The Sun has magnitude -26.5. Sirius, the brightest star in the night sky, has magnitude -1.6. The faintest stars visible with the naked eye have magnitude 6.

The degree of brightness of a star or other object in the sky according to a scale on which the brightest star has a magnitude -1.4 and the faintest visible star has magnitude 6. Sometimes referred to as apparent magnitude. In this scale, each number is 2.5 times the brightness of the previous number. Thus a star with a magnitude of 1 is 100 times brighter than on with a visual magnitude of 6.

A measure of the strength of an earthquake or strain energy released by it, as determined by seismographic observations. The local body- and surface-wave magnitudes will have approximately the same numerical value.

The intensity of an earthquake is described by a number in the Richter scale, called the magnitude. The magnitude of an earthquake is calculated from the logarithm of the amplitude of waves recorded by seismographs. A magnitude 2.0 or less earthquake is called a microearthquake and is not felt by people. A magnitude 4.5 or more earthquake can be measured by seismographs all over the world. Tsunamis can be caused by undersea earthquakes of magnitude 7.5 or greater.

The brightness of an object on a logarithmic scale. "Apparent magnitude" related to how bright an object appears to be, and "absolute magnitude" relates to how bright an object actually is.

A measure of the strength of an earthquake or strain energy released by it, based on amplitude readings on seismographs. The local body- and surface-wave magnitudes will have approximately the same numerical value. There are different types of magnitude scales that are based on different aspects of the earthquake-wave. One type of scale may be more appropriate than another to describe an event depending on the size and relative location of the earthquake.

A measure of the amount of light flux received from a star or other luminous object.

A measure of brightness of celestial objects. Smaller values represent brighter objects than larger values. The magnitude scale is logarithmic whereby a difference in magnitude of 5 is a 100X increase in brightness.

Scale used by astronomers as a measure of the brightness of astronomical objects, based on a system developed by the Greek astronomer Hipparchus, in which he considered the brightest stars to be of the first magnitude, and the dimmest the eye could see to be of the sixth. This system has been refined using a logarithmic scale, where 5.0 magnitudes equals a factor of 100; a difference of a single magnitude is therefore the fifth root of 100, or 2.512. Stars and other objects can be measured to accuracies of .01 magnitude using modern photometric techniques. Counter intuitively, because magnitudes of lower numbers are of greater brightness, the most brilliant objects of all carry negative magnitudes: Sun = mag -27; full Moon -12.5; half Moon -10; Venus -4; Jupiter -2. The brightest stars are approximately magnitude 0. All can be used as comparison objects when estimating the brightness of a meteor or fireball.

Latin "extent" The measure of the strength of the earthquake, which is determined from the seismogram. Can be calculated form the logarithm of the ground-movement's amplitude, it depends on the distance from the epicentre, decreased to such logarithm, to which they give arbitrarily zero value. The Richter's scale uses this expression.

the measurement of the brightness of an object; the lower the number, the brighter the object. absolute: the apparent brightness an object would have if it were 10 parsecs (32.6 light-years) from Earth. apparent: the measure of the brightness of an object as seen from Earth.

A number that characterizes the relative size of an earthquake. Magnitude is based on measurement of the maximum motion recorded by a seismograph. Several scales have been defined, but the most commonly used are (1) local magnitude (ML), commonly referred to as "Richter magnitude," (2) surface-wave magnitude (Ms), (3) body-wave magnitude (Mb), and (4) moment magnitude (Mw). Scales 1-3 have limited range and applicability and do not satisfactorily measure the size of the largest earthquakes. The moment magnitude (Mw) scale, based on the concept of seismic moment, is uniformly applicable to all sizes of earthquakes but is more difficult to compute than the other types. All magnitude scales should yield approximately the same value for any given earthquake.

A measure of an earthquake's size. Magnitude is determined by various methods. Magnitude is an index of the amplitude of the seismic waves created by an earthquake. An increase of one magnitude unit represents a ten--fold amplitude increase. This ten--fold amplitude increase represents about a 32--fold energy increase, for the same duration of shaking (larger quakes generally last longer, releasing even more energy).

A measure of the amount of light received from an object. Higher magnitudes are fainter objects, lower magnitudes are brighter objects.

A measure of an objects brightness. The dimmest meteors one can usually see is 6th magnitude. The lower the magnitude the brighter the object. For instance the full moon is magnitude -13 while Venus usually hovers near magnitude -4. The brightest stars are of magnitudes -1, 0 and +1.

the size of an earthquake as measured on the Richter scale

apparent or absolute luminosity of a celestial body. The former measures the luminosity of the body as seen from the Earth, that is at its true distance. The second one measures the luminosity it would have if located at a standard distance from the observer, that is the intrinsic one. The definition of magnitude is such that, when a star is brighter its magnitude is smaller.

A measure of the strength of a hazard event. The magnitude (also referred to as severity) of a given hazard event is usually determined using technical measures specific to the hazard.

The scale on which the brightness of a star is measured. The brightest stars are first magnitude stars. The faintest stars we can see with the unaided eye are fifth or sixth magnitude. Sixth magnitude stars are 100x fainter than first magnitude stars.

An astronomical measurement of an object's brightness; larger magnitudes represent fainter objects.

Magnitude is the most commonly reported measure of an earthquake's size. They defined it in terms of the amplitude of ground velocity recorded on a particular seismograph, scaled by the distance from the instrument to the earthquake.

A measure of earthquake size which describes the amount of energy released.

used to quantify brightness. Based on the ancient system of Hipparchus but refined and quantified for measurements today such that a ratio of 100 in brightness corresponds to a magnitude difference of 5. Fainter objects have larger, positive magnitudes (closer to positive infinity), while brighter objects have lower magnitudes (closer to negative infinity).

The degree of brightness of a celestial body designated on a numerical scale, on which the brightest star has magnitude -1.4 and the faintest visible star has magnitude 6, with the scale rule such that a decrease of one unit represents an increase in apparent brightness by a factor of 2.512; also called apparent magnitude.

an arbitrary number, measured on a logarithmic scale, used to indicate the brightness of an object. The brighter the star, the lower the numerical value of the magnitude and very bright objects have negative magnitudes.

(1) The quantifiable size of a natural event. (2) A quantitative measure of the size of an earthquake using the Richter scale.

A general term for a measure of the strength or energy of an earthquake as determined from seismographic information. (Local Magnitude) A measure of the strain energy released by an earthquake within 100 kilometers of its epicenter. Strictly defined by Charles Richter as the base-10 logarithm of the amplitude, in microns, of the largest trace deflection that would be observed on a standard torsion seismograph at a distance of 100 km from the epicenter.

How bright a celestial body is.

a number representing the intensity of a star's apparent brightness.

the brightness of a star or other celestial object. The higher the magnitude, the fainter the object. A 1st-magnitude star is 100 times brighter than a 6th-magnitude star.

The brightness of an astronomical object. On a clear, Moonless night in a location away from any light pollution, the faintest star visible to the naked eye will be about magnitude 6. In a city, keen eyed observers may spot stars brighter than about magnitude 3.

**Related Terms:**Scalar , Ratio, Unit, Multiplier, Quantity, Proportional, Logarithm, 23, Square, Order of magnitude, Infinitesimal, Determinant, Absolute value, Pi, Square root, Vector quantity, Multiplicative inverse, Square number, Imaginary number, Vector, Equation, Power, Numeric expression, Place value, Complex number, Array, Quantitative, Scientific notation, Factor , Reciprocal, Cardinal number, Expanded notation, Coefficient , Scalar , Exponent, Gaussian integer, Mole, Unit vector, Geometric mean, Transcendental number, Natural logarithm, Mantissa , Floating-point number, Decimal, Irrational number, Cube root, Rational number, Number , Precision

A property common to both vectors and scalars. In the graphical representation of a vector, the vectorâ€(tm)s magnitude is equal to the length of the arrow.

The "amount" associated with a vector; the vector stripped of any information about its direction.

The magnitude indicates the current value of a quantity.

a number assigned to the ratio of two quantities; two quantities are of the same order of magnitude if one is less than 10 times as large as the other; the number of magnitudes that the quantities differ is specified to within a power of 10

Magnitude is a property that can be quantitatively described, such as the volume of a sphere or the length of a vector.

The value of a scalar, the length of a vector, the area of a bivector, the volume of a trivector, or the sum of all these in a mixed multivector.

scalar value having physical units.

An amount equal to 10 times a given value; thus if some quantity was 10 times as great as another quantity, it would be an order of magnitude greater; if 100 times as great, it would be larger by two orders of magnitude

Magnitude is a scalar quantity and consists of a number assigned to a quantity enabling comparisons to be made on the basis of the ratio of any two such quantities.

The length of a magnetization vector. In MRI the square root of the sum of the squares of M and M components of transverse magnetization. [ Chapter 2

The value of quantity, such as the number of volts of voltage or the number of amperes of current.

Mathematics. a. A number assigned to a quantity so that it may be compared with other quantities. b. A property that can be quantitatively described, such as the volume of a sphere, the length of a vector, or the value of a voltage or current waveform.

**Related Terms:**Size, Scale, Dimension, Actual size, Nominal size, Dimensions, Large-scale, Scale model, Fractal, Fractal dimension, Similarity, Allometry, Nominal dimension, Vernier, Interval scale, Large, Type size, Size, Size, Measure, Small, Ordinal scale, Scale, Expand, Bulk, Scale, Proportion, Colossal, Size, Scale, Effect size, Vernier scale, Ratio scale, Sizes, Similarity, Multidimensional scaling, Scale drawing, Quadrat, Orders of magnitude, Microcosm, Richter magnitude scale, Homogeneity, Body size, Kurtosis, Nominal scale, Comparing, Indirect measurement, Scale, Scale-up

Extent of dimensions; size; -- applied to things that have length, breadth, and thickness.

That which has one or more of the three dimensions, length, breadth, and thickness.

Greatness; grandeur.

Amount; size; greatness.

the property of relative size or extent; "they tried to predict the magnitude of the explosion"

size; for human subjects purposes, used to refer to the size of risk to a research participant. Must be balanced with probability of the risk.

greatness or extent of size.

The numerical size or measure of an attribute (e.g., the area of a polygon, the volume of a solid).

The magnitude of a mathematical object is its size: a property by which it can be larger or smaller than other objects of the same kind; in technical terms, an ordering of the class of objects to which it belongs.

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Anything of which greater or less can be predicated, as time, weight, force, and the like.

The magnitude of an explosive eruption is the total mass of material erupted in an event.

Greatness, in reference to influence or effect; importance; as, an affair of magnitude.

relative importance; "a problem of the first magnitude"