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Equinox

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visible on the horizon, whereas sunset is the instant when the trailing edge of the disk disappears below the horizon. These are the moments of first and last direct sunlight. At these times the center of the disk is below the horizon. Furthermore, atmospheric refraction causes the Sun's disk to appear higher in the sky than it would if the Earth had no atmosphere. Thus, in the morning the upper edge of the disk is visible for several minutes before the geometric edge of the disk reaches the horizon. Similarly, in the evening the upper edge of the disk disappears several minutes after the geometric disk has passed below the horizon. The times of sunrise and sunset in almanacs are calculated for the normal atmospheric refraction of 34 minutes of arc and a
3412: 1014:, believed to have been coined in the 1980s, achieved more widespread recognition in the 21st century. At the most precise measurements, a true equilux is rare, because the lengths of day and night change more rapidly than any other time of the year around the equinoxes. In the mid-latitudes, daylight increases or decreases by about three minutes per day at the equinoxes, and thus adjacent days and nights only reach within one minute of each other. The date of the closest approximation of the equilux varies slightly by latitude; in the mid-latitudes, it occurs a few days before the spring equinox and after the fall equinox in each respective hemisphere. 708: 1130: 820:, which means he wanted to move the vernal equinox to the date on which it fell at that time (21 March is the day allocated to it in the Easter table of the Julian calendar), and to maintain it at around that date in the future, which he achieved by reducing the number of leap years from 100 to 97 every 400 years. However, there remained a small residual variation in the date and time of the vernal equinox of about ±27 hours from its mean position, virtually all because the distribution of 24 hour centurial leap-days causes large jumps (see 688: 937: 728: 744: 2674: 1346:. The newer meaning of "equilux" is modern (c. 1985 to 1986), and not usually intended: Technical references since the beginning of the 20th century (c. 1910) have used the terms "equilux" and "isophot" interchangeably to mean "of equal illumination" in the context of curves showing how intensely lighting equipment will illuminate a surface. See for instance Walsh (1947). The earliest confirmed use of the modern meaning was in a post on the 3448: 3400: 3436: 890:: names referring to the apparent direction of motion of the Sun. The northward equinox occurs in March when the Sun crosses the equator from south to north, and the southward equinox occurs in September when the Sun crosses the equator from north to south. These terms can be used unambiguously for other planets. They are rarely seen, although were first proposed over 100 years ago. 3424: 854:= autumn). These are the historically universal and still most widely used terms for the equinoxes, but are potentially confusing because in the southern hemisphere the vernal equinox does not occur in spring and the autumnal equinox does not occur in autumn. The equivalent common language English terms 1108:
the satellite relative to Earth (i.e. within the beam-width of the ground-station antenna) for a short period each day. The Sun's immense power and broad radiation spectrum overload the Earth station's reception circuits with noise and, depending on antenna size and other factors, temporarily disrupt
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On the date of the equinox, the center of the Sun spends a roughly equal amount of time above and below the horizon at every location on the Earth, so night and day are about the same length. Sunrise and sunset can be defined in several ways, but a widespread definition is the time that the top limb
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For the same reason, this is also the time when the Sun rises for an observer at one of Earth's rotational poles and sets at the other. For a brief period lasting approximately four days, both North and South Poles are in daylight. For example, in 2021 sunrise on the North Pole is 18 March 07:09 UTC,
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These effects make the day about 14 minutes longer than the night at the equator and longer still towards the poles. The real equality of day and night only happens in places far enough from the equator to have a seasonal difference in day length of at least 7 minutes, actually occurring a
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and rely only on battery power. Usually, a satellite travels either north or south of the Earth's shadow because Earth's axis is not directly perpendicular to a line from the Earth to the Sun at other times. During the equinox, since geostationary satellites are situated above the Equator, they are
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On the day of an equinox, the geometric center of the Sun's disk crosses the equator, and this point is above the horizon for 12 hours everywhere on the Earth. However, the Sun is not simply a geometric point. Sunrise is defined as the instant when the leading edge of the Sun's disk becomes
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A third correction for the visual observation of a sunrise (or sunset) is the angle between the apparent horizon as seen by an observer and the geometric (or sensible) horizon. This is known as the dip of the horizon and varies from 3 arcminutes for a viewer standing on the sea shore to
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The dates of the equinoxes change progressively during the leap-year cycle, because the Gregorian calendar year is not commensurate with the period of the Earth's revolution about the Sun. It is only after a complete Gregorian leap-year cycle of 400 years that the seasons commence at
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160 arcminutes for a mountaineer on Everest. The effect of a larger dip on taller objects (reaching over 2½° of arc on Everest) accounts for the phenomenon of snow on a mountain peak turning gold in the sunlight long before the lower slopes are illuminated.
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approximately the same time. In the 21st century the earliest March equinox will be 19 March 2096, while the latest was 21 March 2003. The earliest September equinox will be 21 September 2096 while the latest was 23 September 2003 (
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than light from the Sun. This phenomenon occurs once every 14.7 years on average, and can last a few weeks before and after the exact equinox. Saturn's most recent equinox was on 11 August 2009, and its next will take place on 6 May 2025.
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or degrade the circuit. The duration of those effects varies but can range from a few minutes to an hour. (For a given frequency band, a larger antenna has a narrower beam-width and hence experiences shorter duration "Sun outage" windows.)
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of 16 minutes of arc for the disk. Therefore, at the tabulated time the geometric center of the Sun is actually 50 minutes of arc below a regular and unobstructed horizon for an observer on the surface of the Earth in a level
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and eventually noted the midpoint between the two. Later it was realized that this happens on a day when the duration of the day and the night are practically equal and the word "equinox" comes from Latin
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Freeth, T., Bitsakis, Y., Moussas, X., Seiradakis, J. H., Tselikas, A., Mangou, H., ... & Allen, M. (2006). Decoding the ancient Greek astronomical calculator known as the Antikythera Mechanism.
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in 45 BC, he set 25 March as the date of the spring equinox; this was already the starting day of the year in the Persian and Indian calendars. Because the Julian year is longer than the
1985: 540:(night). On the day of an equinox, daytime and nighttime are of approximately equal duration all over the planet. Contrary to popular belief, they are not exactly equal because of the 1354:
can only be traced to an extremely small (less than six) number of predominantly U.S. American people in such online media for the next 20 years until its broader adoption as a
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edge-on facing the Sun. As a result, they are visible only as a thin line when seen from Earth. When seen from above – a view seen during an equinox for the first time from the
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and sunset on the South Pole is 22 March 13:08 UTC. Also in 2021, sunrise on the South Pole is 20 September 16:08 UTC, and sunset on the North Pole is 24 September 22:30 UTC.
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the equator, rather than north or south of the equator. On the day of the equinox, the Sun appears to rise "due east" and set "due west". This occurs twice each year, around
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is directly perpendicular to the Sun-Earth line, tilting neither toward nor away from the Sun. In modern times, since the Moon (and to a lesser extent the planets) causes
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Contour plot of the hours of daylight as a function of latitude and day of the year, showing approximately 12 hours of daylight at all latitudes during the equinoxes
677:(September) marks the beginning of autumn. Ancient Greek calendars too had the beginning of the year either at the autumnal or vernal equinox and some at solstices. The 2578: 2267: 988:
few days towards the winter side of each equinox. One result of this is that, at latitudes below ±2.0 degrees, all the days of the year are longer than the nights.
2501: 1569: 880:, for example). Although the terms have become very common in the 21st century, they were sometimes used at least as long ago as the mid-20th century. 727: 1350:
group net.astro, which refers to "discussion last year exploring the reasons why equilux and equinox are not coincident". Use of this particular pseudo-Latin
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From the Earth, the Sun appears as a disc rather than a point of light, so when the centre of the Sun is below the horizon, its upper edge may be visible.
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are even more ambiguous. It has become increasingly common for people to refer to the September equinox in the southern hemisphere as the Vernal equinox.
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at a point on the equatorial line. The subsolar point crosses the equator moving northward at the March equinox and southward at the September equinox.
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by about 11.3 minutes on average (or 1 day in 128 years), the calendar "drifted" with respect to the two equinoxes – so that in
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Prior to the 1980s there was no generally accepted term for the phenomenon, and the word "equilux" was more commonly used as a synonym for
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The relation between the Earth, Sun, and stars at the March equinox. From Earth's perspective, the Sun appears to move along the
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Equinoxes are defined on any planet with a tilted rotational axis. A dramatic example is Saturn, where the equinox places its
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Mars's most recent equinoxes were on 12 January 2024 (northern autumn), and on 26 December 2022 (northern spring).
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the spring equinox occurred on about 21 March, and by the 1580s AD it had drifted backwards to 11 March.
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Yallop, B.D.; Hohenkerk, C.Y.; Bell, S.A. (2013). "Astronomical Phenomena". In Urban, S.E.; Seidelmann, P. K. (eds.).
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of the Sun is level with the horizon. With this definition, the day is longer than the night at the equinoxes:
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sunlight. As a result, an observer sees daylight before the top of the Sun's disk appears above the horizon.
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is increasing at the fastest at the vernal equinox and decreasing at the fastest at the autumnal equinox.
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Forsythe, William C.; Rykiel, Edward J.; Stahl, Randal S.; Wu, Hsin-i; Schoolfield, Robert M. (1995).
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also experience difficulties maintaining power during the equinox because they have to travel through
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The equinoxes are sometimes regarded as the start of spring and autumn. A number of traditional
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Vernal equinox and autumnal equinox: these classical names are direct derivatives of Latin (
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Semi-annual astronomical event where the Sun is directly above the Earth's equator
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which is spring equinox in northern hemisphere. This day marks the new year in
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This article is about an astronomical event. For the celestial coordinates, see
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Diagram of the Earth's seasons as seen from the south. Far left: June solstice.
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is assumed to be 34 arcminutes, and the assumed semidiameter (apparent
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The date on which the day and night are exactly the same is known as an
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satellites, there are a few days around the equinox when the Sun goes
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People in countries including Iran, Afghanistan, Tajikistan celebrate
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More precisely, an equinox is traditionally defined as the time when
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Goddess Alive!: Inviting Celtic & Norse Goddesses Into Your Life
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in most cultures and is considered the start of the New Year in the
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Grewal, Mohinder S.; Weill, Lawrence R.; Andrews, Angus P. (2007).
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The times of sunset and sunrise vary with the observer's location (
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and other factors cause the dates of both events to vary slightly.
580: 43: 2452:"Table of times of spring Equinox for a thousand years: 1452–2547" 1384:"Earth's Seasons - Equinoxes, Solstices, Perihelion, and Aphelion" 1254:– a satellite phenomenon that occurs around the time of an equinox 3369: 3325: 3164: 3154: 3084: 2867: 2732: 1257: 1096:
One effect of equinoctial periods is the temporary disruption of
1084:, have often chosen the equinox as their reference point for the 954: 950: 642: 638: 609: 579:, the reverse is true. During the year, equinoxes alternate with 557: 479: 452: 3447: 2320:"How satellites are affected by the spring and autumn equinoxes" 1832:
Global Positioning Systems, Inertial Navigation, and Integration
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Manual of Style/Dates and numbers#Julian and Gregorian calendars
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This article follows the customary Knowledge style detailed at
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Religious architecture is often determined by the equinox; the
1052: 973: 901: 774: 734: 456: 502:, the equinox is officially defined by the Sun's more regular 3139: 2951: 2850: 2805: 2074:"NOAA Global Monitoring Laboratory Solar Calculation Details" 1973:. Krishna Prakashan Media. pp. 233ff. GGKEY:RDRHQ35FBX7. 694: 514: 475: 3294: 3144: 3129: 3119: 2573: 2510: 1524: 1379: 553: 549: 3423: 2579:
International Earth Rotation and Reference Systems Service
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The American practical navigator: An epitome of navigation
1570:"Autumn arrives: The fall equinox explained in six images" 1521:"ESRL Global Monitoring Division - Global Radiation Group" 769:
In other words, the equinoxes are the only times when the
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Textbook of Illuminating Engineering (Intermediate Grade)
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Blackburn, Bonnie J.; Holford-Strevens, Leofranc (1999).
1723: 698: 483: 448: 2422:"Day and Night World Map (night and day map on equinox)" 1712:
Sunrise and sunset times in 90°00'S, 0°00'E (South Pole)
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Sunrise and sunset times in 90°00'N, 0°00'E (North Pole)
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Here, "day" refers to when the Sun is above the horizon.
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during which the sun rises in a perfect alignment over
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On Words: Insights into how our words work – and don't
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in Earth's shadow for the longest duration all year.
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as seen from the north. Far right: December solstice.
2430:"Calculation of Length of Day (Formulas and Graphs)" 2458: 1631: 2509: 2028:Explanatory Supplement to the Astronomical Almanac 1828: 1634:Explanatory supplement to the astronomical almanac 1191:– fairies believed to appear on the spring equinox 1141:reflect little sunlight, as seen in this image by 571:is called the vernal or spring equinox while the 3460: 2218:. University of Alaska Press. pp. 117–124. 1822: 1161:space probe in 2009 – they receive very little 575:is called the autumnal or fall equinox. In the 486:'s disk. Equivalently, this is the moment when 661:(March) conventionally marks the beginning of 3264: 2495: 1754:. Oxford University Press. pp. 250–251. 1658:"March Equinox – Equal Day and Night, Nearly" 1627: 1625: 1218:– days of worship in Japan that began in 1878 1124: 1048:are celebrated on the date of the equinoxes. 1902: 3373: 3351: 3329: 3303: 982:perihelion in January than aphelion in July 773:is on the equator, meaning that the Sun is 534: 526: 518: 482:passes through the geometric center of the 3271: 3257: 2502: 2488: 2367: 2317: 2189:"On the equinox, are day and night equal?" 1888:. Allied Publishers. 2016. pp. 31ff. 1805:Orbital Mechanics for Engineering Students 1795: 1752:Mapping Time: The Calendar and its History 1622: 1472: 1470: 754:The equinoxes are the only times when the 88: 85: 82: 79: 69: 64: 59: 54: 2089:"Correcting Sextant Measurements for Dip" 2025: 1908: 1835:. John Wiley & Sons. pp. 459ff. 1808:. Butterworth-Heinemann. pp. 188ff. 1603:"The Equinox Is Not What You Think It Is" 1202:– occurs around 5 July (see formula) 1026:have been observed during the equinoxes. 3033:International Commission on Stratigraphy 2238: 1855: 1768: 1749: 1728:. Oxford University Press. p. 135. 1430:Équinoxe de printemps entre 1583 et 2999 1378:Astronomical Applications Department of 1128: 1091: 940:Earth at the September 2022 equinox 935: 927: 2265: 2086: 1567: 1467: 1405:"Solstices and Equinoxes: 2001 to 2100" 717:(red), which is tilted compared to the 3461: 2115:"Equinox, Equilux, and Twilight Times" 1915:. Marion Street Press. pp. 89ff. 1801: 1781:. Llewellyn Worldwide. pp. 69ff. 681:predicts the equinoxes and solstices. 3278: 3252: 2483: 2213: 2138: 2112: 1600: 1568:Grieser, Justin (22 September 2014). 615: 2266:Johnson, Walter (18 November 2011). 1774: 560:, the daytime duration is 12 hours. 2459:Gray, Meghan; Merrifield, Michael. 2318:Abrahamian, David (17 April 2018). 2026:Seidelman, P. Kenneth, ed. (1992). 1492:from the original on 21 August 2019 1371: 1029: 924:Length of equinoctial day and night 13: 2139:Walsh, John William Tudor (1947). 908:has shifted these points into the 904:the Sun is entering. However, the 14: 3505: 2753:Discrete time and continuous time 2414: 2087:Biegert, Mark (21 October 2015). 1601:Plait, Phil (22 September 2023). 1452:Équinoxe d’automne de 1583 Ă  2999 3446: 3434: 3422: 3410: 3398: 2678: 2672: 1957:. Oxford University Press. 1895. 1740:Reprinted with corrections 2003. 1726:The Oxford companion to the year 1582:from the original on 8 June 2021 1040:September equinox § Culture 822:Gregorian calendar leap solstice 742: 726: 706: 686: 657:In the northern hemisphere, the 2392: 2361: 2339: 2311: 2286: 2259: 2239:DiBiasio, Jame (15 July 2013). 2232: 2207: 2181: 2167: 2149: 2132: 2106: 2080: 2066: 2044: 2019: 1977: 1961: 1945: 1929: 1876: 1849: 1743: 1717: 1705: 1693: 1676: 1650: 1594: 1561: 1555:United States Naval Observatory 1543: 1486:United States Naval Observatory 1482:Astronomical Information Center 1336: 1327: 1314: 1297: 1080:, since the recommendations of 827: 628:Equinox (celestial coordinates) 21:Equinox (celestial coordinates) 3484:Technical factors of astrology 2826:History of timekeeping devices 2347:"PIA11667: The Rite of Spring" 2272:. Cambridge University Press. 2113:Owens, Steve (20 March 2010). 1909:La Rocque, Paula (2007). 1513: 1456: 1445: 1434: 1423: 1397: 1280: 1206:Geocentric view of the seasons 968:In sunrise/sunset tables, the 816:in 325 AD concerning the 1: 2269:Byways in British Archaeology 2216:The Aurora Watcher's Handbook 2177:. U.K. Meteorological Office. 1531:. U.S. Department of Commerce 1441:Solstice d’étĂ© de 1583 Ă  2999 1364: 1189:Anjana (Cantabrian mythology) 637:Systematically observing the 590:Hemisphere-neutral names are 513:The word is derived from the 447:is a moment in time when the 3474:Dynamics of the Solar System 2294:"Satellite Sun Interference" 2013:10.1016/0304-3800(94)00034-F 1856:Bowditch, Nathaniel (2002). 1274: 1165:; indeed, they receive more 1036:March equinox § Culture 669:, Hindu, and the Persian or 7: 2773:Gravitational time dilation 2609:Barycentric Coordinate Time 2157:"Spring Equilux Approaches" 1176: 906:precession of the equinoxes 455:, which is to say, appears 10: 3510: 2629:Geocentric Coordinate Time 2614:Barycentric Dynamical Time 2552:Coordinated Universal Time 2175:"The Equinox and Solstice" 1802:Curtis, Howard D. (2013). 1125:Equinoxes on other planets 1033: 1017: 632: 625: 619: 18: 3286: 3183: 3074: 3041: 3015: 2896: 2796: 2783:Time-translation symmetry 2713: 2687: 2670: 2594:International Atomic Time 2544: 2521: 1320:This is possible because 1292:proleptic Julian calendar 1098:communications satellites 900:: names referring to the 762:are equally illuminated. 412: 383: 354: 325: 296: 267: 238: 209: 180: 151: 122: 117: 114: 111: 108: 105: 102: 99: 96: 93: 76: 51: 2473:University of Nottingham 2443:The Nuttall Encyclopædia 1750:Richards, E. G. (1998). 1311:, which means "new day". 976:) of the Sun is 16  860:autumn (or fall) equinox 840: 808:to establish the modern 650:, meaning "equal", and 25:Equinox (disambiguation) 3317: 3043:Astronomical chronology 3016:Archaeology and geology 2723:Absolute space and time 2639:IERS Reference Meridian 2634:International Date Line 2545:International standards 1775:Skye, Michelle (2007). 1237:Perihelion and aphelion 1232:Orientation of churches 1086:orientation of churches 960:The Earth's atmosphere 780: 733:Diagram of the Earth's 3374: 3352: 3330: 3304: 2465:"Solstice and Equinox" 2093:Math Encounters (blog) 1322:atmospheric refraction 1148: 970:atmospheric refraction 941: 933: 546:atmospheric refraction 535: 527: 519: 23:. For other uses, see 3489:September observances 3002:Weekday determination 2888:Sundial markup schema 2404:The Planetary Society 2378:The Planetary Society 2119:Dark Sky Diary (blog) 1132: 1092:Effects on satellites 1074:is one such example. 939: 931: 679:Antikythera mechanism 488:Earth's rotation axis 3023:Chronological dating 2763:Theory of relativity 2624:Daylight saving time 2438:"Equinoctial Points" 2214:Davis, Neil (1992). 2052:"Sunrise and Sunset" 1993:Ecological Modelling 1551:Astronomical Almanac 1268:Zoroastrian calendar 1057:Solar Hijri calendar 894:First point of Aries 451:crosses the Earth's 3233:Time value of money 3028:Geologic time scale 2883:History of sundials 2748:Cosmological decade 2700:Greenwich Mean Time 2531:Orders of magnitude 2242:The Story of Angkor 2005:1995EcMod..80...87F 1970:Spherical Astronomy 1885:Exploring the Earth 1608:Scientific American 1575:The Washington Post 1114:geostationary orbit 896:and first point of 804:This drift induced 654:, meaning "night". 577:Southern Hemisphere 565:Northern Hemisphere 506:rather than by its 48: 3208:Mental chronometry 2836:Marine chronometer 2688:Obsolete standards 2245:. Silkworm Books. 1411:. 20 February 2018 1195:Angkor Wat Equinox 1149: 1137:is at equinox its 1064:Angkor Wat Equinox 942: 934: 902:astrological signs 810:Gregorian calendar 616:Equinoxes on Earth 504:ecliptic longitude 32: 3494:Time in astronomy 3479:March observances 3386: 3385: 3280:Wheel of the Year 3246: 3245: 3056:Nuclear timescale 2738:Continuous signal 2369:Lakdawalla, Emily 2279:978-0-521-22877-0 2252:978-1-63102-259-3 2054:. 21 October 2002 1954:Notes and Queries 1938:Popular Astronomy 1922:978-1-933338-20-0 1895:978-81-8424-408-3 1869:978-0-939837-54-0 1842:978-0-470-09971-1 1815:978-0-08-097748-5 1788:978-0-7387-1080-8 1714:, timeanddate.com 1702:, timeanddate.com 1643:978-1-891389-85-6 1557:. 2008. Glossary. 1529:www.esrl.noaa.gov 1263:Wheel of the Year 1211:Iranian calendars 1078:Catholic churches 1046:harvest festivals 1024:conjugate auroras 888:southward equinox 884:Northward equinox 870:September equinox 814:Council of Nicaea 806:Pope Gregory XIII 719:celestial equator 671:Iranian calendars 667:Assyrian calendar 604:September equinox 600:southward equinox 592:northward equinox 573:September equinox 441: 440: 37:date and time of 3501: 3451: 3450: 3439: 3438: 3437: 3427: 3426: 3415: 3414: 3403: 3402: 3401: 3394: 3379: 3361:Autumnal equinox 3357: 3335: 3322: 3309: 3273: 3266: 3259: 3250: 3249: 2947:Dominical letter 2878:Equation of time 2841:Marine sandglass 2682: 2676: 2654:Terrestrial Time 2511:Time measurement 2504: 2497: 2490: 2481: 2480: 2476: 2455: 2447: 2433: 2425: 2408: 2407: 2396: 2390: 2389: 2387: 2385: 2365: 2359: 2358: 2356: 2354: 2343: 2337: 2336: 2334: 2332: 2315: 2309: 2308: 2306: 2304: 2290: 2284: 2283: 2263: 2257: 2256: 2236: 2230: 2229: 2211: 2205: 2204: 2202: 2200: 2185: 2179: 2178: 2171: 2165: 2164: 2163:. 14 March 1986. 2153: 2147: 2146: 2136: 2130: 2129: 2127: 2125: 2110: 2104: 2103: 2101: 2099: 2084: 2078: 2077: 2070: 2064: 2063: 2061: 2059: 2048: 2042: 2041: 2023: 2017: 2016: 1990: 1981: 1975: 1974: 1965: 1959: 1958: 1949: 1943: 1942: 1933: 1927: 1926: 1906: 1900: 1899: 1880: 1874: 1873: 1853: 1847: 1846: 1826: 1820: 1819: 1799: 1793: 1792: 1772: 1766: 1765: 1747: 1741: 1739: 1721: 1715: 1709: 1703: 1697: 1691: 1690:(7119), 587-591. 1680: 1674: 1673: 1671: 1669: 1654: 1648: 1647: 1629: 1620: 1619: 1617: 1615: 1598: 1592: 1591: 1589: 1587: 1565: 1559: 1558: 1547: 1541: 1540: 1538: 1536: 1517: 1511: 1510: 1499: 1497: 1488:. 14 June 2019. 1474: 1465: 1463:Solstice d’hiver 1460: 1454: 1449: 1443: 1438: 1432: 1427: 1421: 1420: 1418: 1416: 1401: 1395: 1394: 1392: 1390: 1375: 1359: 1340: 1334: 1331: 1325: 1318: 1312: 1305:Iranian calendar 1303:The year in the 1301: 1295: 1284: 1082:Charles Borromeo 1030:Cultural aspects 874:Islamic calendar 789:established the 775:exactly overhead 756:solar terminator 746: 730: 710: 693:Illumination of 690: 675:autumnal equinox 538: 530: 522: 49: 31: 3509: 3508: 3504: 3503: 3502: 3500: 3499: 3498: 3459: 3458: 3457: 3445: 3435: 3433: 3421: 3409: 3399: 3397: 3389: 3387: 3382: 3339:Summer solstice 3282: 3277: 3247: 3242: 3179: 3070: 3037: 3011: 2892: 2792: 2743:Coordinate time 2715:Time in physics 2709: 2683: 2677: 2668: 2540: 2517: 2508: 2450: 2436: 2428: 2420: 2417: 2412: 2411: 2400:"Mars Calendar" 2398: 2397: 2393: 2383: 2381: 2371:(7 July 2016). 2366: 2362: 2352: 2350: 2345: 2344: 2340: 2330: 2328: 2316: 2312: 2302: 2300: 2292: 2291: 2287: 2280: 2264: 2260: 2253: 2237: 2233: 2226: 2212: 2208: 2198: 2196: 2195:. 19 March 2024 2187: 2186: 2182: 2173: 2172: 2168: 2155: 2154: 2150: 2137: 2133: 2123: 2121: 2111: 2107: 2097: 2095: 2085: 2081: 2072: 2071: 2067: 2057: 2055: 2050: 2049: 2045: 2038: 2024: 2020: 1988: 1982: 1978: 1967: 1966: 1962: 1951: 1950: 1946: 1935: 1934: 1930: 1923: 1907: 1903: 1896: 1882: 1881: 1877: 1870: 1854: 1850: 1843: 1827: 1823: 1816: 1800: 1796: 1789: 1773: 1769: 1762: 1748: 1744: 1736: 1722: 1718: 1710: 1706: 1698: 1694: 1681: 1677: 1667: 1665: 1656: 1655: 1651: 1644: 1630: 1623: 1613: 1611: 1599: 1595: 1585: 1583: 1566: 1562: 1549: 1548: 1544: 1534: 1532: 1519: 1518: 1514: 1495: 1493: 1476: 1475: 1468: 1461: 1457: 1450: 1446: 1439: 1435: 1428: 1424: 1414: 1412: 1409:AstroPixels.com 1403: 1402: 1398: 1388: 1386: 1376: 1372: 1367: 1362: 1341: 1337: 1332: 1328: 1319: 1315: 1302: 1298: 1285: 1281: 1277: 1272: 1179: 1127: 1106:directly behind 1094: 1042: 1034:Main articles: 1032: 1020: 955:eastern horizon 926: 919:, respectively. 878:Hebrew calendar 843: 830: 791:Julian calendar 783: 750: 747: 738: 731: 722: 711: 702: 691: 635: 630: 624: 618: 500:perfect ellipse 47: 38: 28: 17: 12: 11: 5: 3507: 3497: 3496: 3491: 3486: 3481: 3476: 3471: 3456: 3455: 3443: 3431: 3419: 3407: 3384: 3383: 3381: 3380: 3367: 3358: 3345: 3336: 3323: 3313:Vernal equinox 3310: 3297: 3287: 3284: 3283: 3276: 3275: 3268: 3261: 3253: 3244: 3243: 3241: 3240: 3235: 3230: 3228:Time metrology 3225: 3220: 3215: 3210: 3205: 3204: 3203: 3193: 3187: 3185: 3184:Related topics 3181: 3180: 3178: 3177: 3172: 3167: 3162: 3157: 3152: 3147: 3142: 3137: 3132: 3127: 3122: 3117: 3112: 3107: 3102: 3097: 3092: 3087: 3081: 3079: 3072: 3071: 3069: 3068: 3063: 3058: 3053: 3047: 3045: 3039: 3038: 3036: 3035: 3030: 3025: 3019: 3017: 3013: 3012: 3010: 3009: 3004: 2999: 2994: 2989: 2984: 2979: 2974: 2969: 2964: 2959: 2954: 2949: 2944: 2939: 2934: 2929: 2923: 2918: 2913: 2908: 2902: 2900: 2894: 2893: 2891: 2890: 2885: 2880: 2875: 2873:Dialing scales 2870: 2865: 2860: 2859: 2858: 2848: 2843: 2838: 2833: 2828: 2823: 2818: 2813: 2808: 2802: 2800: 2794: 2793: 2791: 2790: 2785: 2780: 2775: 2770: 2765: 2760: 2755: 2750: 2745: 2740: 2735: 2730: 2725: 2719: 2717: 2711: 2710: 2708: 2707: 2705:Prime meridian 2702: 2697: 2695:Ephemeris time 2691: 2689: 2685: 2684: 2671: 2669: 2667: 2666: 2664:180th meridian 2661: 2656: 2651: 2646: 2641: 2636: 2631: 2626: 2621: 2616: 2611: 2606: 2601: 2596: 2591: 2586: 2581: 2576: 2571: 2566: 2561: 2560: 2559: 2548: 2546: 2542: 2541: 2539: 2538: 2533: 2528: 2522: 2519: 2518: 2507: 2506: 2499: 2492: 2484: 2478: 2477: 2456: 2448: 2434: 2426: 2416: 2415:External links 2413: 2410: 2409: 2391: 2360: 2338: 2310: 2285: 2278: 2258: 2251: 2231: 2224: 2206: 2180: 2166: 2148: 2131: 2105: 2079: 2065: 2043: 2036: 2018: 1976: 1960: 1944: 1928: 1921: 1901: 1894: 1875: 1868: 1848: 1841: 1821: 1814: 1794: 1787: 1767: 1761:978-0192862051 1760: 1742: 1734: 1716: 1704: 1692: 1675: 1649: 1642: 1621: 1593: 1560: 1542: 1512: 1466: 1455: 1444: 1433: 1422: 1396: 1369: 1368: 1366: 1363: 1361: 1360: 1335: 1326: 1313: 1296: 1278: 1276: 1273: 1271: 1270: 1265: 1260: 1255: 1249: 1244: 1239: 1234: 1229: 1224: 1219: 1213: 1208: 1203: 1197: 1192: 1186: 1180: 1178: 1175: 1126: 1123: 1118:Earth's shadow 1112:Satellites in 1093: 1090: 1031: 1028: 1019: 1016: 966: 965: 958: 925: 922: 921: 920: 910:constellations 891: 881: 863: 856:spring equinox 850:= spring, and 842: 839: 835:Universal Time 829: 826: 818:date of Easter 782: 779: 771:subsolar point 752: 751: 748: 741: 739: 732: 725: 723: 712: 705: 703: 701:at the equinox 692: 685: 659:vernal equinox 634: 631: 620:Main article: 617: 614: 457:directly above 439: 438: 435: 432: 429: 426: 423: 420: 417: 414: 410: 409: 406: 403: 400: 397: 394: 391: 388: 385: 381: 380: 377: 374: 371: 368: 365: 362: 359: 356: 352: 351: 348: 345: 342: 339: 336: 333: 330: 327: 323: 322: 319: 316: 313: 310: 307: 304: 301: 298: 294: 293: 290: 287: 284: 281: 278: 275: 272: 269: 265: 264: 261: 258: 255: 252: 249: 246: 243: 240: 236: 235: 232: 229: 226: 223: 220: 217: 214: 211: 207: 206: 203: 200: 197: 194: 191: 188: 185: 182: 178: 177: 174: 171: 168: 165: 162: 159: 156: 153: 149: 148: 145: 142: 139: 136: 133: 130: 127: 124: 120: 119: 116: 113: 110: 107: 104: 101: 98: 95: 91: 90: 87: 84: 81: 78: 74: 73: 68: 63: 58: 53: 33: 15: 9: 6: 4: 3: 2: 3506: 3495: 3492: 3490: 3487: 3485: 3482: 3480: 3477: 3475: 3472: 3470: 3467: 3466: 3464: 3454: 3449: 3444: 3442: 3432: 3430: 3425: 3420: 3418: 3413: 3408: 3406: 3396: 3395: 3392: 3378: 3377: 3371: 3368: 3366: 3362: 3359: 3356: 3355: 3349: 3346: 3344: 3340: 3337: 3334: 3333: 3327: 3324: 3321: 3320: 3314: 3311: 3308: 3307: 3301: 3298: 3296: 3292: 3289: 3288: 3285: 3281: 3274: 3269: 3267: 3262: 3260: 3255: 3254: 3251: 3239: 3236: 3234: 3231: 3229: 3226: 3224: 3221: 3219: 3216: 3214: 3211: 3209: 3206: 3202: 3199: 3198: 3197: 3194: 3192: 3189: 3188: 3186: 3182: 3176: 3173: 3171: 3168: 3166: 3163: 3161: 3158: 3156: 3153: 3151: 3148: 3146: 3143: 3141: 3138: 3136: 3133: 3131: 3128: 3126: 3123: 3121: 3118: 3116: 3113: 3111: 3108: 3106: 3103: 3101: 3098: 3096: 3093: 3091: 3088: 3086: 3083: 3082: 3080: 3078: 3077:units of time 3073: 3067: 3066:Sidereal time 3064: 3062: 3059: 3057: 3054: 3052: 3051:Galactic year 3049: 3048: 3046: 3044: 3040: 3034: 3031: 3029: 3026: 3024: 3021: 3020: 3018: 3014: 3008: 3007:Weekday names 3005: 3003: 3000: 2998: 2997:Tropical year 2995: 2993: 2990: 2988: 2985: 2983: 2980: 2978: 2975: 2973: 2970: 2968: 2965: 2963: 2962:Intercalation 2960: 2958: 2955: 2953: 2950: 2948: 2945: 2943: 2940: 2938: 2935: 2933: 2930: 2928:(lunar Hijri) 2927: 2924: 2922: 2919: 2917: 2914: 2912: 2909: 2907: 2904: 2903: 2901: 2899: 2895: 2889: 2886: 2884: 2881: 2879: 2876: 2874: 2871: 2869: 2866: 2864: 2861: 2857: 2854: 2853: 2852: 2849: 2847: 2844: 2842: 2839: 2837: 2834: 2832: 2829: 2827: 2824: 2822: 2819: 2817: 2814: 2812: 2809: 2807: 2804: 2803: 2801: 2799: 2795: 2789: 2786: 2784: 2781: 2779: 2776: 2774: 2771: 2769: 2768:Time dilation 2766: 2764: 2761: 2759: 2756: 2754: 2751: 2749: 2746: 2744: 2741: 2739: 2736: 2734: 2731: 2729: 2726: 2724: 2721: 2720: 2718: 2716: 2712: 2706: 2703: 2701: 2698: 2696: 2693: 2692: 2690: 2686: 2681: 2675: 2665: 2662: 2660: 2657: 2655: 2652: 2650: 2647: 2645: 2642: 2640: 2637: 2635: 2632: 2630: 2627: 2625: 2622: 2620: 2617: 2615: 2612: 2610: 2607: 2605: 2604:24-hour clock 2602: 2600: 2599:12-hour clock 2597: 2595: 2592: 2590: 2587: 2585: 2582: 2580: 2577: 2575: 2572: 2570: 2567: 2565: 2562: 2558: 2555: 2554: 2553: 2550: 2549: 2547: 2543: 2537: 2534: 2532: 2529: 2527: 2524: 2523: 2520: 2516: 2512: 2505: 2500: 2498: 2493: 2491: 2486: 2485: 2482: 2474: 2470: 2469:Sixty Symbols 2466: 2462: 2457: 2453: 2449: 2445: 2444: 2439: 2435: 2431: 2427: 2423: 2419: 2418: 2405: 2401: 2395: 2380: 2379: 2374: 2370: 2364: 2348: 2342: 2327: 2326: 2321: 2314: 2299: 2295: 2289: 2281: 2275: 2271: 2270: 2262: 2254: 2248: 2244: 2243: 2235: 2227: 2225:0-912006-60-9 2221: 2217: 2210: 2194: 2190: 2184: 2176: 2170: 2162: 2158: 2152: 2144: 2143: 2135: 2120: 2116: 2109: 2094: 2090: 2083: 2075: 2069: 2053: 2047: 2039: 2037:0-935702-68-7 2033: 2029: 2022: 2014: 2010: 2006: 2002: 1998: 1994: 1987: 1980: 1972: 1971: 1964: 1956: 1955: 1948: 1940: 1939: 1932: 1924: 1918: 1914: 1913: 1905: 1897: 1891: 1887: 1886: 1879: 1871: 1865: 1861: 1860: 1852: 1844: 1838: 1834: 1833: 1825: 1817: 1811: 1807: 1806: 1798: 1790: 1784: 1780: 1779: 1771: 1763: 1757: 1753: 1746: 1737: 1735:0-19-214231-3 1731: 1727: 1720: 1713: 1708: 1701: 1696: 1689: 1685: 1679: 1663: 1662:Time and Date 1659: 1653: 1645: 1639: 1635: 1628: 1626: 1610: 1609: 1604: 1597: 1581: 1577: 1576: 1571: 1564: 1556: 1552: 1546: 1530: 1526: 1522: 1516: 1509: 1506: 1491: 1487: 1483: 1479: 1473: 1471: 1464: 1459: 1453: 1448: 1442: 1437: 1431: 1426: 1410: 1406: 1400: 1385: 1381: 1374: 1370: 1357: 1353: 1349: 1345: 1339: 1330: 1323: 1317: 1310: 1306: 1300: 1293: 1289: 1283: 1279: 1269: 1266: 1264: 1261: 1259: 1256: 1253: 1250: 1248: 1245: 1243: 1240: 1238: 1235: 1233: 1230: 1228: 1225: 1223: 1220: 1217: 1214: 1212: 1209: 1207: 1204: 1201: 1198: 1196: 1193: 1190: 1187: 1185: 1182: 1181: 1174: 1171: 1168: 1164: 1160: 1159: 1154: 1146: 1145: 1140: 1136: 1131: 1122: 1119: 1115: 1110: 1107: 1103: 1102:geostationary 1099: 1089: 1087: 1083: 1079: 1075: 1073: 1069: 1065: 1060: 1058: 1054: 1049: 1047: 1041: 1037: 1027: 1025: 1022:Mirror-image 1015: 1013: 1009: 1004: 1000: 998: 994: 989: 985: 983: 979: 975: 971: 963: 959: 956: 952: 948: 947: 946: 938: 930: 918: 914: 911: 907: 903: 899: 895: 892: 889: 885: 882: 879: 875: 871: 867: 866:March equinox 864: 861: 857: 853: 849: 845: 844: 838: 836: 825: 823: 819: 815: 811: 807: 802: 800: 796: 795:tropical year 792: 788: 787:Julius Caesar 778: 776: 772: 767: 763: 761: 757: 745: 740: 736: 729: 724: 720: 716: 709: 704: 700: 696: 689: 684: 683: 682: 680: 676: 672: 668: 664: 660: 655: 653: 649: 644: 640: 629: 623: 613: 611: 607: 605: 601: 597: 596:March equinox 593: 588: 586: 582: 578: 574: 570: 569:March equinox 566: 561: 559: 555: 552:and sets due 551: 547: 543: 539: 537: 531: 529: 523: 521: 516: 511: 509: 505: 501: 497: 496:vary slightly 493: 492:Earth's orbit 489: 485: 481: 477: 473: 468: 466: 462: 458: 454: 450: 446: 436: 433: 430: 427: 424: 421: 418: 415: 411: 407: 404: 401: 398: 395: 392: 389: 386: 382: 378: 375: 372: 369: 366: 363: 360: 357: 353: 349: 346: 343: 340: 337: 334: 331: 328: 324: 320: 317: 314: 311: 308: 305: 302: 299: 295: 291: 288: 285: 282: 279: 276: 273: 270: 266: 262: 259: 256: 253: 250: 247: 244: 241: 237: 233: 230: 227: 224: 221: 218: 215: 212: 208: 204: 201: 198: 195: 192: 189: 186: 183: 179: 175: 172: 169: 166: 163: 160: 157: 154: 150: 146: 143: 140: 137: 134: 131: 128: 125: 121: 92: 75: 72: 67: 62: 57: 50: 45: 41: 36: 30: 26: 22: 3213:Decimal time 2956: 2942:Astronomical 2821:Complication 2816:Atomic clock 2468: 2461:Haran, Brady 2441: 2394: 2382:. Retrieved 2376: 2363: 2351:. Retrieved 2341: 2329:. Retrieved 2323: 2313: 2301:. Retrieved 2297: 2288: 2268: 2261: 2241: 2234: 2215: 2209: 2197:. Retrieved 2193:earthsky.org 2192: 2183: 2169: 2160: 2151: 2145:. I. Pitman. 2141: 2134: 2122:. Retrieved 2118: 2108: 2098:22 September 2096:. Retrieved 2092: 2082: 2068: 2058:22 September 2056:. Retrieved 2046: 2027: 2021: 1999:(1): 87–95. 1996: 1992: 1979: 1969: 1963: 1953: 1947: 1937: 1931: 1911: 1904: 1884: 1878: 1858: 1851: 1831: 1824: 1804: 1797: 1777: 1770: 1751: 1745: 1725: 1719: 1707: 1695: 1687: 1683: 1678: 1666:. Retrieved 1661: 1652: 1633: 1612:. Retrieved 1606: 1596: 1584:. Retrieved 1573: 1563: 1550: 1545: 1533:. Retrieved 1528: 1515: 1505:semidiameter 1501: 1494:. Retrieved 1481: 1458: 1447: 1436: 1425: 1413:. Retrieved 1408: 1399: 1387:. 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Index

Equinox (celestial coordinates)
Equinox (disambiguation)
UT
equinoxes
solstices
equinox
solstice
equinox
solstice
Sun
equator
directly above
20 March
23 September
the plane
Earth
equator
Sun
Earth's rotation axis
Earth's orbit
vary slightly
perfect ellipse
ecliptic longitude
declination
Latin
angular size
atmospheric refraction
east
west
sundial

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