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Equinox. A solar equinox is a moment in time when the Sun crosses the Earth's equator, which is to say, appears directly above 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 20 March and 23 September.
Solstice. A solstice is the time when the Sun reaches its most northerly or southerly excursion relative to the celestial equator on the celestial sphere. Two solstices occur annually, around 20-22 June and 20-22 December. In many countries, the seasons of the year are defined by reference to the solstices and the equinoxes .
A plot of hours of daylight as a function of the date for changing latitudes. This plot was created using the simple sunrise equation, approximating the sun as a single point and does not take into account effects caused by the atmosphere or the diameter of the Sun. The sunrise equation or sunset equation can be used to derive the time of ...
In astronomy, an analemma ( / ˌænəˈlɛmə /; from Ancient Greek ἀνάλημμα (analēmma) 'support') [ a] is a diagram showing the position of the Sun in the sky as seen from a fixed location on Earth at the same mean solar time, as that position varies over the course of a year. The diagram will resemble a figure eight.
In fact it happens two days of the year, during the equinoxes. The solstices are the dates that the Sun stays farthest away from the zenith but also in those cases it's high in the sky, reaching an altitude of 66.56° either to the north or the south. All days of the year, solstices included, have the same length of 12 hours.
Fundal height, or McDonald's rule, is a measure of the size of the uterus used to assess fetal growth and development during pregnancy. It is measured from the top of the mother's uterus to the top of the mother's pubic symphysis. Fundal height, when expressed in centimeters, roughly corresponds to gestational age in weeks between 16 and 36 ...
The 45th parallel north is often called the halfway point between the equator and the North Pole, but the true halfway point is 16.0 km (9.9 mi) north of it (approximately between 45°08'36" and 45°08'37") because Earth is an oblate spheroid; that is, it bulges at the equator and is flattened at the poles. [ 1]
Age in days. This template is used on approximately 4,600 pages and changes may be widely noticed. Test changes in the template's /sandbox or /testcases subpages, or in your own user subpage. Consider discussing changes on the talk page before implementing them. This template returns the number of days between two dates.