Difference between revisions of "Absolute Magnitude"
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− | '''Magnitude''' is a measure of the brightness of | + | [[File: Wiki Navy.png|right]] |
− | + | '''Magnitude''' is a measure of the brightness of a [[star]], [[planet]], or other object in [[space]]. The scale is logarithmic and the brighter the object the lower the number. | |
+ | |||
+ | Magnitude is usually one of two types: | ||
+ | # ''Apparent Magnitude'' (m) and... | ||
+ | # ''Absolute Magnitude'' (M). [[Absolute Magnitude]] is the brightness at 10 [[parsec]]s distance. | ||
− | + | == Description ([[Specifications]]) == | |
− | + | Given the absolute magnitude and the distance to a star, the apparent magnitude can be calculated by: <math>m = M + 5((\log_{10}D)-1)</math> where D is the distance in Parsecs (must be adjusted for extra galactic objects). Thus [[Antares (star)|Antares]] at M -5.28 as seen from [[Capital (world)|Capital]] (distance of ~38 parsecs) would be:<br><math>m = -5.28 + 5((\log_{10}38)-1)</math><br><math>m = -5.28 + 5(1.58-1)</math><br><math>m = -5.28 + 5(0.58)</math><br><math>m=-5.28 + 2.9</math><br><math>m=-2.38</math> | |
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− | + | === Absolute/Apparent Magnitude === | |
− | |||
Absolute/Apparent Magnitudes for comparison: | Absolute/Apparent Magnitudes for comparison: | ||
− | {| | + | {| class="wikitable sortable" |
+ | |+ Absolute/Apparent Magnitude | ||
+ | |- | ||
! Object | ! Object | ||
− | ! | + | ! Absolute Magnitude |
! Apparent Magnitude (Terra) | ! Apparent Magnitude (Terra) | ||
! Apparent Magnitude (Capital) | ! Apparent Magnitude (Capital) | ||
|- | |- | ||
− | |Sun | + | | [[Sun]] |
| 4.83 | | 4.83 | ||
| −26.73 | | −26.73 | ||
| 10.38 | | 10.38 | ||
|- | |- | ||
− | |Moon (full) | + | | [[Moon|Moon (full)]] |
| n/a | | n/a | ||
| −12.6 | | −12.6 | ||
| n/a | | n/a | ||
|- | |- | ||
− | |Visible during Daylight | + | | Visible during Daylight |
| n/a | | n/a | ||
| −3.9 | | −3.9 | ||
| -3.9 | | -3.9 | ||
|- | |- | ||
− | |Moon (new) | + | | Moon (new) |
| n/a | | n/a | ||
| –2.5 | | –2.5 | ||
| n/a | | n/a | ||
|- | |- | ||
− | |[[Sirius (star)|Sirius]] Brightest Star | + | | [[Sirius (star)|Sirius]] Brightest Star |
| 1.42 | | 1.42 | ||
| −1.47 | | −1.47 | ||
Line 73: | Line 74: | ||
| 12.8 | | 12.8 | ||
|} | |} | ||
− | *Note the numbers in () above are for adjusted locations of stars on the | + | * Note the numbers in () above are for adjusted locations of [[star]]s on the maps. |
− | {{Sources|S1=Wikipedia (various)}} | + | |
− | {{ | + | == History & Background ([[Dossier]]) == |
+ | On ancient [[Terra]] the stars of the sky were divided into 6 magnitudes, with 1 being the brightest and 6 the faintest with each division being approximately 2 times difference, this was later revised so that a 1<sup>st</sup> magnitude star was 100 times brighter than a 6<sup>th</sup> magnitude star. First [[Polaris (star)|Polaris]] then [[Vega (star)|Vega]] were taken to be the 0 point on the scale. So each step is the fifth root of 100 different (2.512). | ||
+ | |||
+ | Magnitude is not limited to the 0-6 scale, most primary stars will be highly negative ([[Sol]] from [[Terra]] is −26.73). The faintest magnitude visible with a [[Humaniti|human]] eye is 6.5. [[Binoculars]] give 9.5, and an 8m [[Ground Telescope]] can resolve to 27. | ||
+ | |||
+ | * '''Apparent Magnitude:''' A measure of its brightness as seen by an observer on the ground, normalized to the value it would have in the absence of the atmosphere | ||
+ | * '''Absolute Magnitude:''' The apparent magnitude, an object would have if it were at a standard luminosity distance away from us, in the absence of interstellar extinction | ||
+ | |||
+ | == References & Contributors ([[Sources]]) == | ||
+ | {{Advanced}} | ||
+ | {{Sources | ||
+ | |S1= Wikipedia (various) | ||
+ | |S2= [[Traveller Wiki Editorial Team]] | ||
+ | |S3= Author & Contributor: Lord (Marquis) and Master of Sophontology [[User:Maksim-Smelchak|Maksim-Smelchak]] of the [[Ministry of Science]] | ||
+ | }} | ||
+ | |||
+ | |||
+ | {{MET|Metric|Science|}} |
Latest revision as of 00:08, 17 March 2019
Magnitude is a measure of the brightness of a star, planet, or other object in space. The scale is logarithmic and the brighter the object the lower the number.
Magnitude is usually one of two types:
- Apparent Magnitude (m) and...
- Absolute Magnitude (M). Absolute Magnitude is the brightness at 10 parsecs distance.
Description (Specifications)[edit]
Given the absolute magnitude and the distance to a star, the apparent magnitude can be calculated by: <math>m = M + 5((\log_{10}D)-1)</math> where D is the distance in Parsecs (must be adjusted for extra galactic objects). Thus Antares at M -5.28 as seen from Capital (distance of ~38 parsecs) would be:
<math>m = -5.28 + 5((\log_{10}38)-1)</math>
<math>m = -5.28 + 5(1.58-1)</math>
<math>m = -5.28 + 5(0.58)</math>
<math>m=-5.28 + 2.9</math>
<math>m=-2.38</math>
Absolute/Apparent Magnitude[edit]
Absolute/Apparent Magnitudes for comparison:
Object | Absolute Magnitude | Apparent Magnitude (Terra) | Apparent Magnitude (Capital) |
---|---|---|---|
Sun | 4.83 | −26.73 | 10.38 |
Moon (full) | n/a | −12.6 | n/a |
Visible during Daylight | n/a | −3.9 | -3.9 |
Moon (new) | n/a | –2.5 | n/a |
Sirius Brightest Star | 1.42 | −1.47 | 6.97 |
Canopus 2nd Brightest star | −5.53 | -0.7 (-2.04) | (0.73) |
Vega 5th Brightest star | 0.58 | 0.03 | 5.96 |
Antares 16th Brightest star | −5.28 | 1.09 (0.83) | -1.35 (-2.38) |
Deneb 19th Brightest star | −8.73 | 1.25 (-2.2) | 0.96 (-3.09) |
LBV 1806-20 | −14.2 | 8.4 | 8.4 |
Quasar 3C 273 | −26.7 | 12.8 | 12.8 |
- Note the numbers in () above are for adjusted locations of stars on the maps.
History & Background (Dossier)[edit]
On ancient Terra the stars of the sky were divided into 6 magnitudes, with 1 being the brightest and 6 the faintest with each division being approximately 2 times difference, this was later revised so that a 1st magnitude star was 100 times brighter than a 6th magnitude star. First Polaris then Vega were taken to be the 0 point on the scale. So each step is the fifth root of 100 different (2.512).
Magnitude is not limited to the 0-6 scale, most primary stars will be highly negative (Sol from Terra is −26.73). The faintest magnitude visible with a human eye is 6.5. Binoculars give 9.5, and an 8m Ground Telescope can resolve to 27.
- Apparent Magnitude: A measure of its brightness as seen by an observer on the ground, normalized to the value it would have in the absence of the atmosphere
- Absolute Magnitude: The apparent magnitude, an object would have if it were at a standard luminosity distance away from us, in the absence of interstellar extinction
References & Contributors (Sources)[edit]
- Wikipedia (various)
- Traveller Wiki Editorial Team
- Author & Contributor: Lord (Marquis) and Master of Sophontology Maksim-Smelchak of the Ministry of Science