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Orbital pole
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<h2 id="ecliptic-pole">Ecliptic pole</h2> <p>The <a href="/facts/Ecliptic/cJxXDDDW">ecliptic</a> is the plane on which <a href="/facts/Earth%2527s_orbit/BGGCdFag">Earth orbits</a> the <a href="/facts/Sun/CadPCVHh">Sun</a>. The ecliptic poles are the two points where the ecliptic axis, the imaginary line <a href="/facts/Perpendicular/u0k8xqx4">perpendicular</a> to the ecliptic, <a href="/facts/Intersection_(Euclidean_geometry)/RwH57yPq">intersects</a> the <a href="/facts/Celestial_sphere/TYAtXgor">celestial sphere</a>. </p><p>The two ecliptic poles are mapped below. </p> <table><tbody><tr><td>The north ecliptic pole is in <a href="/facts/Draco_(constellation)/bMAUnLGs">Draco</a>.</td><td>The south ecliptic pole is in <a href="/facts/Dorado/SM1WeYuK">Dorado</a>.</td></tr></tbody></table> <p>Due to <a href="/facts/Axial_precession/NQ79x3m3">axial precession</a>, either <a href="/facts/Celestial_pole/5Gj9JJbK">celestial pole</a> completes a circuit around the nearer ecliptic pole every 25,800 years. </p><p>As of 1 January 2000<a href="https://en.wikipedia.org/w/index.php?title=Orbital_pole&action=edit">[update]</a>, the positions of the ecliptic poles expressed in <a href="/facts/Equatorial_coordinate_system/dn5W4Eoo">equatorial coordinates</a>, as a consequence of Earth's <a href="/facts/Axial_tilt/kt7KwL3v">axial tilt</a>, are the following: </p> <ul><li>North: <a href="/facts/Right_ascension/z4CEsTFu">right ascension</a> 18h 0m 0.0s (exact), <a href="/facts/Declination/5X4S4k9u">declination</a> +66° 33′ 38.55″</li> <li>South: right ascension 6h 0m 0.0s (exact), declination −66° 33′ 38.55″</li></ul> <p>The north ecliptic pole is located near the <a href="/facts/Cat%2527s_Eye_Nebula/gvVk41YP">Cat's Eye Nebula</a> and the south ecliptic pole is located near the <a href="/facts/Large_Magellanic_Cloud/7VYAehNa">Large Magellanic Cloud</a>. </p><p>It is impossible anywhere on Earth for either ecliptic pole to be at the <a href="/facts/Zenith/ISuRFp05">zenith</a> in the <a href="/facts/Night_sky/IM1PakDh">night sky</a>. By definition, the ecliptic poles are located 90° from the <a href="/facts/Position_of_the_Sun/rNhWtukM">Sun's position</a>. Therefore, whenever and wherever either ecliptic pole is directly overhead, the Sun must be on the <a href="/facts/Horizon/LxwxWfC2">horizon</a>. The ecliptic poles can contact the zenith only within the <a href="/facts/Arctic_Circle/AlayDpsw">Arctic</a> and <a href="/facts/Antarctic_Circle/8IRf9UHu">Antarctic</a> circles. </p><p>The <a href="/facts/Galactic_coordinates/Un6BambN">galactic coordinates</a> of the north ecliptic pole can be calculated as <i>ℓ</i> = 96.38°, <i>b</i> = 29.81° (see <a href="/facts/Celestial_coordinate_system/23HhqvHj">celestial coordinate system</a>). </p> <h2 id="see-also">See also</h2> <ul><li><a href="/facts/Celestial_pole/5Gj9JJbK">Celestial pole</a></li> <li><a href="/facts/Invariable_plane/SSoYrjeR">Invariable plane</a></li> <li><a href="/facts/Polar_alignment/wq7mx4Uw">Polar alignment</a></li> <li><a href="/facts/Pole_star/FYeWDQ6p">Pole star</a></li> <li><a href="/facts/Poles_of_astronomical_bodies/HEz90QFn">Poles of astronomical bodies</a></li></ul> <h2 id="footnotes">Footnotes</h2> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>Tabulated and mapped data obtained from "HORIZONS web-interface". Solar System Dynamics (ssd.jpl.nasa.gov). JPL / NASA. Retrieved 1 September 2020. — Used HORIZONS input "Ephemeris Type: Orbital Elements", "Time Span: discrete time=2451545", "Center: Sun (body center)", and selected each object's barycenter. Results are instantaneous osculating values at the precise J2000 epoch, and referenced to the ecliptic. <a href="https://ssd.jpl.nasa.gov/horizons.cgi?s_type=1" target="_blank">https://ssd.jpl.nasa.gov/horizons.cgi?s_type=1</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>Tabulated and mapped data obtained from "HORIZONS web-interface". Solar System Dynamics (ssd.jpl.nasa.gov). JPL / NASA. Retrieved 1 September 2020. — Used HORIZONS input "Ephemeris Type: Orbital Elements", "Time Span: discrete time=2451545", "Center: Sun (body center)", and selected each object's barycenter. Results are instantaneous osculating values at the precise J2000 epoch, and referenced to the ecliptic. <a href="https://ssd.jpl.nasa.gov/horizons.cgi?s_type=1" target="_blank">https://ssd.jpl.nasa.gov/horizons.cgi?s_type=1</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>When inclination is very near 0, the location of nodes is somewhat uncertain, and is less useful to orient the orbit. Likewise when latitude is very near a pole (±90°), the longitude is less certain or useful. <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>When inclination is very near 0, the location of nodes is somewhat uncertain, and is less useful to orient the orbit. Likewise when latitude is very near a pole (±90°), the longitude is less certain or useful. <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p>"HST cycle 26 primer orbital constraints". HST User Documentation. hst-docs.stsci.edu. Baltimore, MD: Space Telescope Science Institute. Retrieved 16 July 2022. <a href="https://hst-docs.stsci.edu/hsp/past-hst-proposal-opportunities/the-hubble-space-telescope-primer-for-cycle-26/hst-cycle-26-primer-orbital-constraints" target="_blank">https://hst-docs.stsci.edu/hsp/past-hst-proposal-opportunities/the-hubble-space-telescope-primer-for-cycle-26/hst-cycle-26-primer-orbital-constraints</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li> </ol>