Star magnitude - Revision history

FredericBernard: /* History */ Wikify

2020-07-28T20:06:14Z

‎History: Wikify

FredericBernard: /* History */ Add name to reference

2020-07-28T20:05:49Z

‎History: Add name to reference

FredericBernard: /* Modern definition */

2020-07-28T20:05:23Z

‎Modern definition

FredericBernard: /* History */ Update broken link with a new one

2020-07-28T20:02:46Z

‎History: Update broken link with a new one

FredericBernard: /* Modern definition */

2020-07-28T19:59:42Z

‎Modern definition

FredericBernard: /* Modern definition */ Add distance must be measured in parsecs

2020-07-28T19:59:11Z

‎Modern definition: Add distance must be measured in parsecs

FredericBernard: /* Modern definition */

2020-07-28T19:58:28Z

‎Modern definition

FredericBernard: /* Modern definition */

2020-07-28T19:58:10Z

‎Modern definition

FredericBernard: Expand definitions of apparent and absolute magnitudes

2020-07-28T19:57:26Z

Expand definitions of apparent and absolute magnitudes

FredericBernard: Expand intro a little

2020-07-28T19:43:53Z

Expand intro a little

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 The observation of different brightness of stars is mentioned also in the [[New Testament]]: ''"The sun has one kind of splendor, the moon another and the stars another; and star differs from star in splendor."''<ref>{{cite web |title=Bible, 1 Corinthians 15:41 (New International Version)|publisher=Bible Gateway |url=http://www.biblegateway.com/passage/?search=1+Corinthians+15%3A41&version=NIV|quote=Credit:Holy Bible, New International Version®, NIV® Copyright © 1973, 1978, 1984, 2011 by Biblica, Inc.®}}</ref>
-In 140 AD, Claudius Ptolemy added "greater" and "smaller" within the magnitude to separate them further.
+In 140 AD, [[Claudius Ptolemy]] added "greater" and "smaller" within the magnitude to separate them further.
 With [[Galileo]] and the [[telescope]], it was possible to make out stars that were much dimmer than sixth magnitude.

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 '''Star magnitude''' refers to the apparent brightness of [[star]]s.<ref name=britannica>{{cite web|url=https://www.britannica.com/science/magnitude-astronomy|title=Magnitude|accessdate=July 28, 2020|publisher=britannica}}</ref> More generally, the term "apparent magnitude" is a measure of how bright any astronomical object is as seen from [[Earth]]. The absolute magnitude of an object is the magnitude of the object as seen from 10 [[parsec]]s from the object. Somewhat confusingly, lower magnitudes correspond to brighter objects.
 == History ==
-Stars were first classified by brightness by Hipparchus in 129 BC.  He produced the first well known catalog of stars in which the brightest stars were listed as "first magnitude" and the second grouping was "second magnitude".  This division went up to sixth magnitude.<ref>{{cite web|url=https://www.space.com/21640-star-luminosity-and-magnitude.html|title=Brightest Stars: Luminosity & Magnitude|accessdate=July 28, 2020|publisher=space.com|name=Elizabeth Howell|date=October 11, 2017}}</ref>
+Stars were first classified by brightness by Hipparchus in 129 BC.  He produced the first well known catalog of stars in which the brightest stars were listed as "first magnitude" and the second grouping was "second magnitude".  This division went up to sixth magnitude.<ref name=space.com>{{cite web|url=https://www.space.com/21640-star-luminosity-and-magnitude.html|title=Brightest Stars: Luminosity & Magnitude|accessdate=July 28, 2020|publisher=space.com|name=Elizabeth Howell|date=October 11, 2017}}</ref>
 The observation of different brightness of stars is mentioned also in the [[New Testament]]: ''"The sun has one kind of splendor, the moon another and the stars another; and star differs from star in splendor."''<ref>{{cite web |title=Bible, 1 Corinthians 15:41 (New International Version)|publisher=Bible Gateway |url=http://www.biblegateway.com/passage/?search=1+Corinthians+15%3A41&version=NIV|quote=Credit:Holy Bible, New International Version®, NIV® Copyright © 1973, 1978, 1984, 2011 by Biblica, Inc.®}}</ref>

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 The apparent magnitude of a star, ''m''<sub>*</sub> can be computed using,<ref>{{cite web|url=http://astronomyonline.org/Science/Magnitude.asp#:~:text=A%20Magnitude%20is%20the%20measure,of%20Magnitude%3A%20apparent%20and%20absolute.|title=Formulas - Magnitudes|accessdate=July 28, 2020|publisher=astronomyonline.org}}</ref>
 ::<math>m_* - m_c = -2.5 \log_{10}  \frac{b_*}{b_c}</math>
-where ''m''<sub>c</sub> is the apparent magnitude of a comparison star and ''b''<sub>*</sub> and ''b''<sub>c</sub> are the brightness of the star and comparison star as seen on Earth. The <math>\log_{10}</math> refers to a base 10 [[logarithm]].
+where ''m''<sub>c</sub> is the apparent magnitude of a comparison star and ''b''<sub>*</sub> and ''b''<sub>c</sub> are the brightness of the star and comparison star as seen on Earth. Historically, the star [[Vega]] was used as a comparison and defined to have an apparent magnitude of +0.0, though recent measurements have meant it is now +0.3 in order to be consistent with other stars.<ref name=space.com/> The <math>\log_{10}</math> refers to a base 10 [[logarithm]].
 The apparent magnitude of an object depends not only on how much light the object emits, but also on how far away the object is. To compare the instrinsic brightness of objects, the absolute magnitude is often used. It is defined as the magnitude of an object as seen from 10 [[parsec]]s (32.6156 [[light year]]s). The absolute magnitude, ''M'', can be calculated using,<ref>{{cite web|url=https://astronomy.swin.edu.au/cosmos/A/Absolute+Magnitude|title=Absolute Magnitude|accessdate=July 28, 2020|publisher=astronomy.swin.edu.au}}</ref>

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 '''Star magnitude''' refers to the apparent brightness of [[star]]s.<ref name=britannica>{{cite web|url=https://www.britannica.com/science/magnitude-astronomy|title=Magnitude|accessdate=July 28, 2020|publisher=britannica}}</ref> More generally, the term "apparent magnitude" is a measure of how bright any astronomical object is as seen from [[Earth]]. The absolute magnitude of an object is the magnitude of the object as seen from 10 [[parsec]]s from the object. Somewhat confusingly, lower magnitudes correspond to brighter objects.
 == History ==
-Stars were first classified by brightness by Hipparchus in 129 BC.  He produced the first well known catalog of stars in which the brightest stars were listed as "first magnitude" and the second grouping was "second magnitude".  This division went up to sixth magnitude.<ref>http://skytonight.com/howto/basics/3304516.html</ref>
+Stars were first classified by brightness by Hipparchus in 129 BC.  He produced the first well known catalog of stars in which the brightest stars were listed as "first magnitude" and the second grouping was "second magnitude".  This division went up to sixth magnitude.<ref>{{cite web|url=https://www.space.com/21640-star-luminosity-and-magnitude.html|title=Brightest Stars: Luminosity & Magnitude|accessdate=July 28, 2020|publisher=space.com|name=Elizabeth Howell|date=October 11, 2017}}</ref>
 The observation of different brightness of stars is mentioned also in the [[New Testament]]: ''"The sun has one kind of splendor, the moon another and the stars another; and star differs from star in splendor."''<ref>{{cite web |title=Bible, 1 Corinthians 15:41 (New International Version)|publisher=Bible Gateway |url=http://www.biblegateway.com/passage/?search=1+Corinthians+15%3A41&version=NIV|quote=Credit:Holy Bible, New International Version®, NIV® Copyright © 1973, 1978, 1984, 2011 by Biblica, Inc.®}}</ref>
 In 140 AD, Claudius Ptolemy added "greater" and "smaller" within the magnitude to separate them further.
-With Galileo and the telescope, it was possible to make out stars that were much dimmer than sixth magnitude.
+With [[Galileo]] and the [[telescope]], it was possible to make out stars that were much dimmer than sixth magnitude.
 == Modern definition ==

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 == Modern definition ==
-In the 1800s, Norman R. Pogson proposed and codified magnitude to be a logarithmic scale where the difference between the first and fifth magnitude is one hundred times brighter.  The ratio of one number to the next is the fifth root of one hundred, or about 2.512 - known as the Pogson ratio.<ref name=britannica/> For example, this means a magnitude +5.0 star is about 2.512 times brighter than a magnitude 6.0 star.
+In the 1800s, Norman R. Pogson proposed and codified magnitude to be a logarithmic scale where the difference between the first and fifth magnitude is one hundred times brighter.  The ratio of one number to the next is the fifth root of one hundred, or about 2.512 - known as the Pogson ratio.<ref name=britannica/> For example, this means a magnitude +5.0 star is about 2.512 times brighter than a magnitude +6.0 star.
 The apparent magnitude of a star, ''m''<sub>*</sub> can be computed using,<ref>{{cite web|url=http://astronomyonline.org/Science/Magnitude.asp#:~:text=A%20Magnitude%20is%20the%20measure,of%20Magnitude%3A%20apparent%20and%20absolute.|title=Formulas - Magnitudes|accessdate=July 28, 2020|publisher=astronomyonline.org}}</ref>
 ::<math>m_* - m_c = -2.5 \log_{10}  \frac{b_*}{b_c}</math>
-where ''m''<sub>c</sub> is the apparent magnitude of a comparison star and ''b''<sub>*</sub> and ''b''<sub>c</sub> are the brightness of the star and comparison star as seen on Earth. The <math>\log_10</math> refers to a base 10 [[logarithm]].
+where ''m''<sub>c</sub> is the apparent magnitude of a comparison star and ''b''<sub>*</sub> and ''b''<sub>c</sub> are the brightness of the star and comparison star as seen on Earth. The <math>\log_{10}</math> refers to a base 10 [[logarithm]].
 The apparent magnitude of an object depends not only on how much light the object emits, but also on how far away the object is. To compare the instrinsic brightness of objects, the absolute magnitude is often used. It is defined as the magnitude of an object as seen from 10 [[parsec]]s (32.6156 [[light year]]s). The absolute magnitude, ''M'', can be calculated using,<ref>{{cite web|url=https://astronomy.swin.edu.au/cosmos/A/Absolute+Magnitude|title=Absolute Magnitude|accessdate=July 28, 2020|publisher=astronomy.swin.edu.au}}</ref>

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 The apparent magnitude of an object depends not only on how much light the object emits, but also on how far away the object is. To compare the instrinsic brightness of objects, the absolute magnitude is often used. It is defined as the magnitude of an object as seen from 10 [[parsec]]s (32.6156 [[light year]]s). The absolute magnitude, ''M'', can be calculated using,<ref>{{cite web|url=https://astronomy.swin.edu.au/cosmos/A/Absolute+Magnitude|title=Absolute Magnitude|accessdate=July 28, 2020|publisher=astronomy.swin.edu.au}}</ref>
 :<math>M = m - 5 \log_{10} \frac{d}{10}</math>
-where ''m'' is the apparent magnitude and ''d'' is the distance to the object from Earth.
+where ''m'' is the apparent magnitude and ''d'' is the distance to the object from Earth. ''d'' must be measured in parsecs for this equation to work.
 == Examples ==

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-'''Star magnitude''' refers to the apparent brightness of [[star]]s.
+'''Star magnitude''' refers to the apparent brightness of [[star]]s.<ref name=britannica>{{cite web|url=https://www.britannica.com/science/magnitude-astronomy|title=Magnitude|accessdate=July 28, 2020|publisher=britannica}}</ref> More generally, the term "apparent magnitude" is a measure of how bright any astronomical object is as seen from [[Earth]]. The absolute magnitude of an object is the magnitude of the object as seen from 10 [[parsec]]s from the object. Somewhat confusingly, lower magnitudes correspond to brighter objects.
 == History ==
 Stars were first classified by brightness by Hipparchus in 129 BC.  He produced the first well known catalog of stars in which the brightest stars were listed as "first magnitude" and the second grouping was "second magnitude".  This division went up to sixth magnitude.<ref>http://skytonight.com/howto/basics/3304516.html</ref>
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 ==References==
-<references/>
+{{reflist}}
 {{Stars}}
 [[Category:Astronomy]]