Hokuto Shichi Sei: Difference between revisions

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[[Image:Ursa Major constellation detail map.PNG|325px|thumb|right|Big Dipper map]]
[[Image:Ursa Major constellation detail map.PNG|325px|thumb|right|Big Dipper map]]
The '''Plough''' or the '''Big Dipper''' is an [[asterism (astronomy)|asterism]] of seven [[star]]s that has been recognized as a distinct grouping in many cultures from time immemorial. The comprising stars are the seven brightest of the formal [[constellation]] '''[[Ursa Major]]'''.
The '''Plough''' or the '''Big Dipper''' is an [[wikipedia:asterism (astronomy)|asterism]] of seven [[star]]s that has been recognized as a distinct grouping in many cultures from time immemorial. The comprising stars are the seven brightest of the formal [[constellation]] '''[[wikipedia:Ursa Major|Ursa Major]]'''.


==Names and lore==
==Names and lore==
[[Image:Changchun-Temple-Jiazi-Dian-0347.jpg|thumb|right|The Hall of the Big Dipper in a [[Taoism|Taoist]] temple, [[Wuhan]]]]
[[Image:Changchun-Temple-Jiazi-Dian-0347.jpg|thumb|right|The Hall of the Big Dipper in a [[wikipedia:Taoism|Taoist]] temple, [[Wuhan]]]]
In [[Hindu astronomy]], it is referred to as ''(Vrihat)'' '''[[Saptarishi|Sapta Rishi]]''' meaning "The Seven (Great) Sages".
In [[Hindu astronomy]], it is referred to as ''(Vrihat)'' '''[[wikipedia:Saptarishi|Sapta Rishi]]''' meaning "The Seven (Great) Sages".


Throughout eastern Asia, these stars compose the '''Northern Dipper'''. They are colloquially named "''The Seven Stars of the Northern Dipper''":
Throughout eastern Asia, these stars compose the '''Northern Dipper'''. They are colloquially named "''The Seven Stars of the Northern Dipper''":
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In the same line of sight as [[Mizar (star)|Mizar]], but three light-years beyond it, is the star [[Zeta Ursae Majoris|Alcor]] (80 UMa). Together they are known as the [[Horse and Rider]].  At fourth magnitude, Alcor would normally be relatively easy to see with the unaided eye, but its proximity to Mizar renders it more difficult to resolve, and it has served as a traditional test of sight. Mizar itself has four components and thus enjoys the distinction of being part of an [[optical binary]] as well as being the first-discovered [[telescope|telescopic]] [[binary star|binary]] (1617) and the first-discovered  [[spectroscopic binary]] (1889).
In the same line of sight as [[wikipedia:Mizar (star)|Mizar]], but three light-years beyond it, is the star [[wikipedia:Zeta Ursae Majoris|Alcor]] (80 UMa). Together they are known as the [[Horse and Rider]].  At fourth magnitude, Alcor would normally be relatively easy to see with the unaided eye, but its proximity to Mizar renders it more difficult to resolve, and it has served as a traditional test of sight. Mizar itself has four components and thus enjoys the distinction of being part of an [[optical binary]] as well as being the first-discovered [[telescope|telescopic]] [[binary star|binary]] (1617) and the first-discovered  [[spectroscopic binary]] (1889).


[[File:astro 4D uma rg anim.gif|left|thumb|4D proper moving in -/+ 150 000 years. To view this image you need 3D glasses (red-green or red-blue).]]
[[File:astro 4D uma rg anim.gif|left|thumb|4D proper moving in -/+ 150 000 years. To view this image you need 3D glasses (red-green or red-blue).]]
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Not only are the stars in the Big Dipper easily found themselves, they may also be used as guides to yet other stars. Thus it is often the starting point for introducing Northern Hemisphere beginners to the [[night sky]]:
Not only are the stars in the Big Dipper easily found themselves, they may also be used as guides to yet other stars. Thus it is often the starting point for introducing Northern Hemisphere beginners to the [[night sky]]:
*[[Taikyokusei|Polaris]], the '''North Star''', is found by imagining a line from Merak (β) to Dubhe (α) and then extending it for five times the distance between the two '''Pointers'''.
*[[Taikyokusei|Polaris]], the '''North Star''', is found by imagining a line from Merak (β) to Dubhe (α) and then extending it for five times the distance between the two '''Pointers'''.
*Extending a line from Megrez (δ) to Phecda (γ), on the inside of the bowl, leads to [[Regulus]] (α [[Leo (constellation)|Leonis]]) and [[Alphard]] (α [[Hydra (constellation)|Hydrae]]). A [[mnemonic]] for this is ''"A hole in the bowl will leak on Leo."''
*Crossing the top of the bowl from Megrez (δ) to Dubhe (α) takes one in the direction of [[Capella (star)|Capella]] (α [[wikipedia:Auriga (constellation)|Aurigae]]).  A mnemonic for this is ''"Cap to Capella."''
*Crossing the top of the bowl from Megrez (δ) to Dubhe (α) takes one in the direction of [[Capella (star)|Capella]] (α [[wikipedia:Auriga (constellation)|Aurigae]]).  A mnemonic for this is ''"Cap to Capella."''
*[[Castor (star)|Castor]] (α [[Gemini (constellation)|Geminorum]]) is reached by imagining a diagonal line from Megrez (δ) to Merak (β) and then extending it for approximately five times that distance.
 
*By following the curve of the handle from Alioth (ε) to Mizar (ζ) to Alkaid (η), one reaches [[Arcturus]] (α [[Boötes|Boötis]]) and [[Spica]] (α [[Virgo (constellation)|Virginis]]). A mnemonic for this is ''"Arc to Arcturus then speed to Spica."''
Additionally, the Dipper may be used as a guide to telescopic objects:
Additionally, the Dipper may be used as a guide to telescopic objects:
*The approximate location of the [[Hubble Deep Field]] can be found by following a line from Phecda (γ) to Megrez (δ) and continuing on for the same distance again.
*The approximate location of the [[Hubble Deep Field]] can be found by following a line from Phecda (γ) to Megrez (δ) and continuing on for the same distance again.
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