Difference between revisions of "Obliquity of the ecliptic"

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<div class="definition"><div class="short_definition">The angle between the [[plane of the ecliptic]] (or the plane of the earth's  [[orbit]]) and the plane of the earth's [[equator]]; the &ldquo;tilt&rdquo; of the earth.</div><br/> <div class="paragraph">The obliquity of the ecliptic is computed from the following formula:    <div class="display-formula"><blockquote>[[File:ams2001glos-Oe2.gif|link=|center|ams2001glos-Oe2]]</blockquote></div>    where ''t'' is the year for which the obliquity is desired. For 1999, the value was 23&deg;26&prime;21.89&Prime;. It is  the oblique orientation of the earth's axis relative to its orbit that accounts for the seasons, for, in  the period of a year, the [[angle of incidence]] of [[incoming solar radiation]] varies by nearly 47&deg; at  any one place. Particularly at high latitudes, this results in a great seasonal [[temperature]] contrast.  M. Milankovitch has calculated that the obliquity of the ecliptic varies between 24.5&deg; and 22&deg; in  the course of 40 000 years. This [[variation]] may be considered as a long-period [[climatic control]]  and is included in the astronomical theory of [[ice ages]].</div><br/> </div>
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<div class="definition"><div class="short_definition">The angle between the [[plane of the ecliptic]] (or the plane of the earth's  [[orbit]]) and the plane of the earth's [[equator]]; the "tilt" of the earth.</div><br/> <div class="paragraph">The obliquity of the ecliptic is computed from the following formula:    <div class="display-formula"><blockquote>[[File:ams2001glos-Oe2.gif|link=|center|ams2001glos-Oe2]]</blockquote></div>    where ''t'' is the year for which the obliquity is desired. For 1999, the value was 23&#x000b0;26&prime;21.89&Prime;. It is  the oblique orientation of the earth's axis relative to its orbit that accounts for the seasons, for, in  the period of a year, the [[angle of incidence]] of [[incoming solar radiation]] varies by nearly 47&#x000b0; at  any one place. Particularly at high latitudes, this results in a great seasonal [[temperature]] contrast.  M. Milankovitch has calculated that the obliquity of the ecliptic varies between 24.5&#x000b0; and 22&#x000b0; in  the course of 40 000 years. This [[variation]] may be considered as a long-period [[climatic control]]  and is included in the astronomical theory of [[ice ages]].</div><br/> </div>
 
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Latest revision as of 15:46, 20 February 2012



obliquity of the ecliptic

The angle between the plane of the ecliptic (or the plane of the earth's orbit) and the plane of the earth's equator; the "tilt" of the earth.

The obliquity of the ecliptic is computed from the following formula:
ams2001glos-Oe2
where t is the year for which the obliquity is desired. For 1999, the value was 23°26′21.89″. It is the oblique orientation of the earth's axis relative to its orbit that accounts for the seasons, for, in the period of a year, the angle of incidence of incoming solar radiation varies by nearly 47° at any one place. Particularly at high latitudes, this results in a great seasonal temperature contrast. M. Milankovitch has calculated that the obliquity of the ecliptic varies between 24.5° and 22° in the course of 40 000 years. This variation may be considered as a long-period climatic control and is included in the astronomical theory of ice ages.