]> 2008/06/10 OpenCyc Knowledge Base Copyright© 2001-2008 Cycorp, Inc., http://www.cyc.com/, Austin, TX, USA This file contains an OWL representation of information contained in the OpenCyc Knowledge Base. The content of this OWL file is licensed under the Creative Commons Attribution 3.0 license whose text can be found at http://creativecommons.org/licenses/by/3.0/legalcode. The content of this OWL file, including the OpenCyc content it represents, constitutes the "Work" referred to in the Creative Commons license. The terms of this license equally apply to, without limitation, renamings and other logically equivalent reformulations of the content of this OWL file (or portions thereof) in any natural or formal language, as well as to derivations of this content or inclusion of it in other ontologies. externalID A unique, language-neutral, variable-sized identifier for a concept that can be used to refer unambiguously to that concept across OWL exports or across Cyc inference engines. label A natural-language representation for a concept that is both human readable and readable by the Cyc inference engine. These terms are not guaranteed to refer to the same concept across time but are guaranteed to be consistent within a particular OWL export. Use 'cycAnnot:externalID' for unambiguously referring to a concept across OWL exports or across Cyc inference engines. CelestialEvents-Time-Topic A <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rAmoSCGJbQdiSXZJvYiNhkQ" class="cyc_term">CycVocabularyTopic</a> and a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rtGXkHpNaEdqAAAACs0uFOQ" class="cyc_term">KBDependentCollection</a>. celestial events time topic VernalEquinoxDay vernal equinox A collection of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjeCJwpEbGdrcN5Y29ycA" class="cyc_term">CalendarDay</a>s and an instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvh7QtZwpEbGdrcN5Y29ycA" class="cyc_term">AnnualTemporalObjectType</a>. Each instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVrqkJwpEbGdrcN5Y29ycA" class="cyc_term">VernalEquinoxDay</a> is a calendar-day during which the sun crosses the equator, making daytime (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViHepwpEbGdrcN5Y29ycA" class="cyc_term">DaytimeHours</a>) and nighttime (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVieC5wpEbGdrcN5Y29ycA" class="cyc_term">Night</a>) of equal duration on all parts of the earth, but where daytimes are lengthening and nighttimes shortening in the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjPjpwpEbGdrcN5Y29ycA" class="cyc_term">NorthernHemisphere_Region</a>. A vernal equinox occurs about March 21 each year and marks the end of the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvgEW85wpEbGdrcN5Y29ycA" class="cyc_term">CalendarWinter</a> and beginning of the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvgEXNZwpEbGdrcN5Y29ycA" class="cyc_term">CalendarSpring</a> in the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjPjpwpEbGdrcN5Y29ycA" class="cyc_term">NorthernHemisphere_Region</a>, and the end of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvgEXaJwpEbGdrcN5Y29ycA" class="cyc_term">CalendarSummer</a> and the beginning of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvgEXkJwpEbGdrcN5Y29ycA" class="cyc_term">CalendarAutumn</a> in the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVj5j5wpEbGdrcN5Y29ycA" class="cyc_term">SouthernHemisphere_Region</a>. A specialization of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvgEa3ZwpEbGdrcN5Y29ycA" class="cyc_term">QualitativeTimeOfDay</a>. An instance of this collection is a daily recurring event during which the sun apparently `rises' and `moves' to its `highest' position in the daily cycle, i.e. from a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjNG5wpEbGdrcN5Y29ycA" class="cyc_term">Sunrise</a> to the ensuing noon. The definition is more complex in polar regions in which it is possible that the sun does not rise or set during a day. Morning morning Evening evening A specialization of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvgEa3ZwpEbGdrcN5Y29ycA" class="cyc_term">QualitativeTimeOfDay</a>. An instance of this collection is a regularly recurring celestial event started by an instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvgEHB5wpEbGdrcN5Y29ycA" class="cyc_term">Dusk</a> and <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjI3ZwpEbGdrcN5Y29ycA" class="cyc_term">temporallyCoterminal</a> with the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjeCJwpEbGdrcN5Y29ycA" class="cyc_term">CalendarDay</a> of which it is a part. A collection of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjeCJwpEbGdrcN5Y29ycA" class="cyc_term">CalendarDay</a>s and an instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvh7QtZwpEbGdrcN5Y29ycA" class="cyc_term">AnnualTemporalObjectType</a>. Each instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvWhvypwpEbGdrcN5Y29ycA" class="cyc_term">AutumnalEquinoxDay</a> is a calendar-day during which the sun crosses the equator from north to south, making daytime (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViHepwpEbGdrcN5Y29ycA" class="cyc_term">DaytimeHours</a>) and nighttime (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVieC5wpEbGdrcN5Y29ycA" class="cyc_term">Night</a>) of equal duration on all parts of the earth, but where daytimes are shortening and nighttimes lengthening in the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjPjpwpEbGdrcN5Y29ycA" class="cyc_term">NorthernHemisphere_Region</a>. An autumnal equinox marks the beginning of the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvgEXkJwpEbGdrcN5Y29ycA" class="cyc_term">CalendarAutumn</a> in the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjPjpwpEbGdrcN5Y29ycA" class="cyc_term">NorthernHemisphere_Region</a> and the beginning of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvgEXNZwpEbGdrcN5Y29ycA" class="cyc_term">CalendarSpring</a> in the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVj5j5wpEbGdrcN5Y29ycA" class="cyc_term">SouthernHemisphere_Region</a>. Instances occur about September 22 of each year. AutumnalEquinoxDay autumnal equinox A specialization of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwPcURpwpEbGdrcN5Y29ycA" class="cyc_term">Twilight</a>. Each instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViO45wpEbGdrcN5Y29ycA" class="cyc_term">Dawn</a> is a period of time just before an instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjNG5wpEbGdrcN5Y29ycA" class="cyc_term">Sunrise</a> (q.v.) during which the sky is partially and indirectly illuminated by the sun. dawn Dawn DecemberSolsticeDay A specialization of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjeCJwpEbGdrcN5Y29ycA" class="cyc_term">CalendarDay</a> and an instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvh7QtZwpEbGdrcN5Y29ycA" class="cyc_term">AnnualTemporalObjectType</a>. Each instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rYPM8uVe8EdaQLQACs0uFOQ" class="cyc_term">DecemberSolsticeDay</a> is a calendar day (usually December 21) which is either a summer solstice day (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVprG5wpEbGdrcN5Y29ycA" class="cyc_term">SummerSolsticeDay</a>) in the southern hemisphere or a winter solstice day (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvV3GDZwpEbGdrcN5Y29ycA" class="cyc_term">WinterSolsticeDay</a>) in the northern hemisphere. December solstice Sunrise A specialization of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvgEa3ZwpEbGdrcN5Y29ycA" class="cyc_term">QualitativeTimeOfDay</a>. Each instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjNG5wpEbGdrcN5Y29ycA" class="cyc_term">Sunrise</a> is an event during which, at a given location, the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rlxNJlmKqEdqAAAACs71DGQ" class="cyc_term">Sun</a> appears to clear the horizon as it "rises". An instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjNG5wpEbGdrcN5Y29ycA" class="cyc_term">Sunrise</a> occurs at a given place even if the visibility of the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rlxNJlmKqEdqAAAACs71DGQ" class="cyc_term">Sun</a> is impaired due to obscuring objects such as clouds. Every instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjNG5wpEbGdrcN5Y29ycA" class="cyc_term">Sunrise</a> immediately follows (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVin4pwpEbGdrcN5Y29ycA" class="cyc_term">contiguousAfter</a>) some instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViO45wpEbGdrcN5Y29ycA" class="cyc_term">Dawn</a> (q.v.), and every instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViHepwpEbGdrcN5Y29ycA" class="cyc_term">DaytimeHours</a> (q.v.) is started by (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjWYJwpEbGdrcN5Y29ycA" class="cyc_term">temporallyStartedBy</a>) an instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjNG5wpEbGdrcN5Y29ycA" class="cyc_term">Sunrise</a>. sunrise night <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVieC5wpEbGdrcN5Y29ycA" class="cyc_term">Night</a> is a specialization of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvgEa3ZwpEbGdrcN5Y29ycA" class="cyc_term">QualitativeTimeOfDay</a>, and it is the temporal complement of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViHepwpEbGdrcN5Y29ycA" class="cyc_term">DaytimeHours</a>. Each instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVieC5wpEbGdrcN5Y29ycA" class="cyc_term">Night</a> is <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVin4pwpEbGdrcN5Y29ycA" class="cyc_term">contiguousAfter</a> an instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViHepwpEbGdrcN5Y29ycA" class="cyc_term">DaytimeHours</a>, and vice versa. Each instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVieC5wpEbGdrcN5Y29ycA" class="cyc_term">Night</a> intersects two different <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjeCJwpEbGdrcN5Y29ycA" class="cyc_term">CalendarDay</a>s. Each instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVieC5wpEbGdrcN5Y29ycA" class="cyc_term">Night</a> is <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjWYJwpEbGdrcN5Y29ycA" class="cyc_term">temporallyStartedBy</a> a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvgEHB5wpEbGdrcN5Y29ycA" class="cyc_term">Dusk</a>, <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVio05wpEbGdrcN5Y29ycA" class="cyc_term">temporallyFinishedBy</a> a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViO45wpEbGdrcN5Y29ycA" class="cyc_term">Dawn</a>, <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVin4pwpEbGdrcN5Y29ycA" class="cyc_term">contiguousAfter</a> a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViIQ5wpEbGdrcN5Y29ycA" class="cyc_term">Sunset</a>, and has a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjNG5wpEbGdrcN5Y29ycA" class="cyc_term">Sunrise</a> which is <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVin4pwpEbGdrcN5Y29ycA" class="cyc_term">contiguousAfter</a> it. Night SummerSolsticeDay summer solstice A collection of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjeCJwpEbGdrcN5Y29ycA" class="cyc_term">CalendarDay</a>s and an instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvh7QtZwpEbGdrcN5Y29ycA" class="cyc_term">AnnualTemporalObjectType</a>. Each instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVprG5wpEbGdrcN5Y29ycA" class="cyc_term">SummerSolsticeDay</a> is a calendar-day during which the sun is farthest into the hemisphere of reference, e.g. being furthest north of the equator when considered in the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjPjpwpEbGdrcN5Y29ycA" class="cyc_term">NorthernHemisphere_Region</a>, making the daytime (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViHepwpEbGdrcN5Y29ycA" class="cyc_term">DaytimeHours</a>) the longest of the year in that <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVj2hZwpEbGdrcN5Y29ycA" class="cyc_term">GeographicalHemisphere</a> and the shortest of the year in the opposite one. The summer solstice occurs around June 21 or 22 each year in the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjPjpwpEbGdrcN5Y29ycA" class="cyc_term">NorthernHemisphere_Region</a> and marks the end of the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvgEXNZwpEbGdrcN5Y29ycA" class="cyc_term">CalendarSpring</a> and beginning of the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvgEXaJwpEbGdrcN5Y29ycA" class="cyc_term">CalendarSummer</a>. See <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rYPM8uFe8EdaQLQACs0uFOQ" class="cyc_term">JuneSolsticeDay</a> and <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rYPM8uVe8EdaQLQACs0uFOQ" class="cyc_term">DecemberSolsticeDay</a> for reference to the day of year that has the same meaning throughout the time zone. dusk Dusk A specialization of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwPcURpwpEbGdrcN5Y29ycA" class="cyc_term">Twilight</a>. Each instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvgEHB5wpEbGdrcN5Y29ycA" class="cyc_term">Dusk</a> is a dimly-lit period of time which is <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVin4pwpEbGdrcN5Y29ycA" class="cyc_term">contiguousAfter</a> an instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViIQ5wpEbGdrcN5Y29ycA" class="cyc_term">Sunset</a>, and is the event which starts an instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVieC5wpEbGdrcN5Y29ycA" class="cyc_term">Night</a>. A collection of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjeCJwpEbGdrcN5Y29ycA" class="cyc_term">CalendarDay</a>s and an instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvh7QtZwpEbGdrcN5Y29ycA" class="cyc_term">AnnualTemporalObjectType</a>. Each instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvV3GDZwpEbGdrcN5Y29ycA" class="cyc_term">WinterSolsticeDay</a> is a calendar-day during which the sun is farthest from the equator away from the local hemisphere (north or south), making the daytime (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViHepwpEbGdrcN5Y29ycA" class="cyc_term">DaytimeHours</a>). The winter solstice occurs around December 21 or 22 each year in the northern hemisphere [<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjPjpwpEbGdrcN5Y29ycA" class="cyc_term">NorthernHemisphere_Region</a>] and about June 21 in the southern hemisphere [<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVj5j5wpEbGdrcN5Y29ycA" class="cyc_term">SouthernHemisphere_Region</a>] and marks the end of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvgEXkJwpEbGdrcN5Y29ycA" class="cyc_term">CalendarAutumn</a> and the beginning of the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvgEW85wpEbGdrcN5Y29ycA" class="cyc_term">CalendarWinter</a>. winter solstice WinterSolsticeDay Afternoon A specialization of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvgEa3ZwpEbGdrcN5Y29ycA" class="cyc_term">QualitativeTimeOfDay</a>. An instance of this collection is the daily celestial event in which the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rlxNJlmKqEdqAAAACs71DGQ" class="cyc_term">Sun</a> moves from its `highest' position in the daily cycle and `sets' or becomes a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwHca55wpEbGdrcN5Y29ycA" class="cyc_term">MidnightSun</a>, i.e from noon till <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViIQ5wpEbGdrcN5Y29ycA" class="cyc_term">Sunset</a> or <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwHca55wpEbGdrcN5Y29ycA" class="cyc_term">MidnightSun</a>. Each <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViGOpwpEbGdrcN5Y29ycA" class="cyc_term">Afternoon</a> is <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVio05wpEbGdrcN5Y29ycA" class="cyc_term">temporallyFinishedBy</a> a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViIQ5wpEbGdrcN5Y29ycA" class="cyc_term">Sunset</a> or <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwHca55wpEbGdrcN5Y29ycA" class="cyc_term">MidnightSun</a>. afternoon twilight A specialization of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvgEa3ZwpEbGdrcN5Y29ycA" class="cyc_term">QualitativeTimeOfDay</a>. <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwPcURpwpEbGdrcN5Y29ycA" class="cyc_term">Twilight</a> is union of the two collections of events, <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViO45wpEbGdrcN5Y29ycA" class="cyc_term">Dawn</a> and <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvgEHB5wpEbGdrcN5Y29ycA" class="cyc_term">Dusk</a>. Each <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwPcURpwpEbGdrcN5Y29ycA" class="cyc_term">Twilight</a> is an event during which the sky is indirectly illuminated by the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rlxNJlmKqEdqAAAACs71DGQ" class="cyc_term">Sun</a>, either just before an instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjNG5wpEbGdrcN5Y29ycA" class="cyc_term">Sunrise</a> or just after an instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViIQ5wpEbGdrcN5Y29ycA" class="cyc_term">Sunset</a>. Twilight midday A specialization of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvgEa3ZwpEbGdrcN5Y29ycA" class="cyc_term">QualitativeTimeOfDay</a>. An instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViHw5wpEbGdrcN5Y29ycA" class="cyc_term">Midday</a> is the daily recurring event during which the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rlxNJlmKqEdqAAAACs71DGQ" class="cyc_term">Sun</a> is near its `highest' position in the daily cycle. A <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViHw5wpEbGdrcN5Y29ycA" class="cyc_term">Midday</a> overlaps the start of an <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViGOpwpEbGdrcN5Y29ycA" class="cyc_term">Afternoon</a>, and a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViIhZwpEbGdrcN5Y29ycA" class="cyc_term">Morning</a> overlaps the start of a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViHw5wpEbGdrcN5Y29ycA" class="cyc_term">Midday</a>. Midday time of day An instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVkAcpwpEbGdrcN5Y29ycA" class="cyc_term">RegularlyRepeatedEventType</a>. Each instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvgEa3ZwpEbGdrcN5Y29ycA" class="cyc_term">QualitativeTimeOfDay</a> is a celestial event such as a dawn (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViO45wpEbGdrcN5Y29ycA" class="cyc_term">Dawn</a>), a morning (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViIhZwpEbGdrcN5Y29ycA" class="cyc_term">Morning</a>), an evening (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVidx5wpEbGdrcN5Y29ycA" class="cyc_term">Evening</a>), etc. On <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVkL_pwpEbGdrcN5Y29ycA" class="cyc_term">PlanetEarth</a>, qualitative times of day are synchronized with the rotation of the earth about its axis, but the absolute timing of qualitative times of day depends upon such factors as the season and the observer's location on the planet's surface. QualitativeTimeOfDay DaytimeHours A specialization of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvgEa3ZwpEbGdrcN5Y29ycA" class="cyc_term">QualitativeTimeOfDay</a>. <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViHepwpEbGdrcN5Y29ycA" class="cyc_term">DaytimeHours</a> is the collection of regularly occurring celestial events during which the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rlxNJlmKqEdqAAAACs71DGQ" class="cyc_term">Sun</a> is above the horizon. This collection is the temporal complement of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVieC5wpEbGdrcN5Y29ycA" class="cyc_term">Night</a> -- every instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViHepwpEbGdrcN5Y29ycA" class="cyc_term">DaytimeHours</a> is <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVin4pwpEbGdrcN5Y29ycA" class="cyc_term">contiguousAfter</a> one instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVieC5wpEbGdrcN5Y29ycA" class="cyc_term">Night</a> and vice versa (except for days in which the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rlxNJlmKqEdqAAAACs71DGQ" class="cyc_term">Sun</a> neither rises nor sets). daytime June solstice JuneSolsticeDay A specialization of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjeCJwpEbGdrcN5Y29ycA" class="cyc_term">CalendarDay</a> and an instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvh7QtZwpEbGdrcN5Y29ycA" class="cyc_term">AnnualTemporalObjectType</a>. Each instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rYPM8uFe8EdaQLQACs0uFOQ" class="cyc_term">JuneSolsticeDay</a> is a calendar day (usually about June 21) which is either a summer solstice day (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVprG5wpEbGdrcN5Y29ycA" class="cyc_term">SummerSolsticeDay</a>) in the northern hemisphere or a winter solstice day (see <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvV3GDZwpEbGdrcN5Y29ycA" class="cyc_term">WinterSolsticeDay</a>) in the southern hemisphere. sunset Sunset Each <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViIQ5wpEbGdrcN5Y29ycA" class="cyc_term">Sunset</a> is an <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViADZwpEbGdrcN5Y29ycA" class="cyc_term">Event</a> in which, at a given location, the horizon occludes the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rlxNJlmKqEdqAAAACs71DGQ" class="cyc_term">Sun</a> as it appears to set. This event is construed to occur regardless of the visibility of the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rlxNJlmKqEdqAAAACs71DGQ" class="cyc_term">Sun</a> due to obscuring objects such as clouds. There is a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvgEHB5wpEbGdrcN5Y29ycA" class="cyc_term">Dusk</a> which is <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVin4pwpEbGdrcN5Y29ycA" class="cyc_term">contiguousAfter</a> each <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViIQ5wpEbGdrcN5Y29ycA" class="cyc_term">Sunset</a>. Every <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViHepwpEbGdrcN5Y29ycA" class="cyc_term">DaytimeHours</a> is <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVio05wpEbGdrcN5Y29ycA" class="cyc_term">temporallyFinishedBy</a> a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViIQ5wpEbGdrcN5Y29ycA" class="cyc_term">Sunset</a> (unless it <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjZtpwpEbGdrcN5Y29ycA" class="cyc_term">endsDuring</a> a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwHca55wpEbGdrcN5Y29ycA" class="cyc_term">MidnightSun</a>), as is every <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViGOpwpEbGdrcN5Y29ycA" class="cyc_term">Afternoon</a>. Time-Topic A <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4r2SZdtGMBQdiOl-Ui2UGs_g" class="cyc_term">CycVocabularyTopLevelTopic</a> and a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rtGXkHpNaEdqAAAACs0uFOQ" class="cyc_term">KBDependentCollection</a>. time-topic A specialization of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rwIE23ZwpEbGdrcN5Y29ycA" class="cyc_term">TimeDependentCollection</a> (q.v.). This is the collection of all and only those collections <code>COL</code> such that any thing's being an instance of <code>COL</code> depends on the current state of the <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvVjqoZwpEbGdrcN5Y29ycA" class="cyc_term">CycKB</a>. Such a <code>COL</code> corresponds to a property defined (at least partly) in terms of the contents, features, or implementation of the Cyc Knowledge Base itself, as opposed to a property that "exists out there" in the KB-independent world. For example, <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvV281JwpEbGdrcN5Y29ycA" class="cyc_term">CycLAssertion</a> is a KB-dependent collection, membership in which requires of a given CycL sentence that it has in fact been asserted to the KB. <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViAoJwpEbGdrcN5Y29ycA" class="cyc_term">CycLSentence</a> is also KB-dependent, as being a CycL sentence requires being composed (ultimately) out of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvu6KTZwpEbGdrcN5Y29ycA" class="cyc_term">CycLReifiedDenotationalTerm</a>s (and perhaps variables) -- i.e. terms that are currently reified in the KB. Conversely, <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rv5ddsJwpEbGdrcN5Y29ycA" class="cyc_term">Sentence</a> is not a KB-dependent collection. See also <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvip9N5wpEbGdrcN5Y29ycA" class="cyc_term">KBDependentRelation</a>. KB dependent collection KBDependentCollection CelestialEvents-Time-Topic A <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rAmoSCGJbQdiSXZJvYiNhkQ" class="cyc_term">CycVocabularyTopic</a> and a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rtGXkHpNaEdqAAAACs0uFOQ" class="cyc_term">KBDependentCollection</a>. celestial events time topic CelestialEvents-Time-Topic A <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rAmoSCGJbQdiSXZJvYiNhkQ" class="cyc_term">CycVocabularyTopic</a> and a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rtGXkHpNaEdqAAAACs0uFOQ" class="cyc_term">KBDependentCollection</a>. celestial events time topic CycVocabularyTopic An instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvprlOZwpEbGdrcN5Y29ycA" class="cyc_term">FacetingCollectionType</a> and a specialization of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rgQsP1F2xEdif1wACs2IMlQ" class="cyc_term">Topic</a>. Each instance of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rAmoSCGJbQdiSXZJvYiNhkQ" class="cyc_term">CycVocabularyTopic</a> is a collection of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViA9JwpEbGdrcN5Y29ycA" class="cyc_term">Thing</a>s falling under a topic for which some Cyc Vocabulary exists. <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rgQsP1F2xEdif1wACs2IMlQ" class="cyc_term">Topic</a> is neither a strict [<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvcZ1FpwpEbGdrcN5Y29ycA" class="cyc_term">facets_Strict</a>] nor a covering [<a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rv86JWpwpEbGdrcN5Y29ycA" class="cyc_term">facets_Covering</a>] faceting of <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViA9JwpEbGdrcN5Y29ycA" class="cyc_term">Thing</a>: many <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rvViA9JwpEbGdrcN5Y29ycA" class="cyc_term">Thing</a>s may be instances of no <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rgQsP1F2xEdif1wACs2IMlQ" class="cyc_term">Topic</a>, or of multiple <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rgQsP1F2xEdif1wACs2IMlQ" class="cyc_term">Topic</a>s. cyc vocabulary topic CelestialEvents-Time-Topic A <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rAmoSCGJbQdiSXZJvYiNhkQ" class="cyc_term">CycVocabularyTopic</a> and a <a href="http://sw.opencyc.org/2008/06/10/concept/Mx4rtGXkHpNaEdqAAAACs0uFOQ" class="cyc_term">KBDependentCollection</a>. celestial events time topic