Spring Meridian is a part of the equinox meridiator that has the celestial longitude 0° (±0°) (0h). It is also called celestial Prime Meridian, First point of Aries Meridian, Pisces Meridian, March Meridian, Vernal Meridian, and Midnight Meridian because during the course of the year, the sun passes through this meridian on March 20 or 21 as it travels from southern to northern hemispheres and western to eastern hemispheres along the ecliptic.
Unlike the geographical Prime Meridian on the world map, the Spring Meridian lies on both ends of the celestial map. But like Prime Meridian, it passes between poles and passes through the equator. Like equator, Spring Meridian divides two celestial hemispheres, though into western hemisphere to the west and eastern hemisphere to the east.
These constellations are best visible in September because the sun is furthest away from these constellations. There are following constellations passing through this meridian in order of decreasing declination (north to south).
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