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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.
21. 14:14. 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.
Subsolar point. The subsolar point on a planet is the point at which its Sun is perceived to be directly overhead (at the zenith); [1] that is, where the Sun's rays strike the planet exactly perpendicular to its surface. It can also mean the point closest to the Sun on an astronomical object, even though the Sun might not be visible.
The Cosmic Calendar is a method to visualize the chronology of the universe, scaling its currently understood age of 13.8 billion years to a single year in order to help intuit it for pedagogical purposes in science education or popular science. In this visualization, the Big Bang took place at the beginning of January 1 at midnight, and the ...
14:14. Earth during the summer solstice in June 2017. The summer solstice or estival solstice[i] occurs when one of Earth 's poles has its maximum tilt toward the Sun. It happens twice yearly, once in each hemisphere (Northern and Southern). For that hemisphere, the summer solstice is the day with the longest period of daylight and shortest ...
Sunrise equation. A contour plot of the hours of daylight as a function of latitude and day of the year, using the most accurate models described in this article. It can be seen that the area of constant day and constant night reach up to the polar circles (here labeled "Anta. c." and "Arct. c."), which is a consequence of the earth's inclination.
The equation of time has zeros near 15 April, 13 June, 1 September, and 25 December. Ignoring very slow changes in the Earth's orbit and rotation, these events are repeated at the same times every tropical year. However, due to the non-integral number of days in a year, these dates can vary by a day or so from year to year.
Illumination of Earth by the Sun on the day of an equinox. The March equinox[7][8] or northward equinox[9] is the equinox on the Earth when the subsolar point appears to leave the Southern Hemisphere and cross the celestial equator, heading northward as seen from Earth. The March equinox is known as the vernal equinox (spring equinox) in the ...