The word vernal is correct and usable in written English.
"Vernal" means relating to the spring season, and can be used when you want to describe something that is related to the spring. For example, "The vernal breeze blew through the trees, carrying the fragrant scent of blooming flowers."
The beginning of Passover is determined by the first full moon after the vernal equinox, which can occur on any day of the week.
To ensure that Easter occurs on a Sunday, the Council of Nicaea therefore ruled in 325AD that Easter would be celebrated on the Sunday after the first full moon on or after the vernal equinox.
"It must nearly be summer," I snickered to myself; such is the vernal regularity of industrial action by controllers across the Channel.
At a meeting held in Aleppo in 1997, representatives of several churches proposed that a new system be adopted from 2001, relying on actual astronomical observations rather than tables to define the dates of the vernal equinox and the full moon.
There are two types of vernal conjunctivitis.
The official Śaka year is the elapsed year, starting from the day following that of the vernal equinox.
Celestial longitude is measured eastward from the ascending intersection of the ecliptic with the equator, a position known as the "first point of Aries," and the place of the Sun at the time of the vernal equinox about March 21.
Right ascension, in astronomy, the east west coordinate by which the position of a celestial body is ordinarily measured; more precisely, it is the angular distance of a body's hour circle east of the vernal equinox, measured along the celestial equator.
The ecliptic is inclined at 23.44° to the plane of the celestial equator; the two points of intersection of the ecliptic and the plane mark the vernal and autumnal equinoxes.
If the stars are used, then the interval is called the sidereal day and is defined by the period between two passages of a star (more precisely of the vernal equinox, a reference point on the celestial sphere) across the meridian: it is 23 hours 56 minutes 4.10 seconds of mean solar time.
Since antiquity, the solar manifestations of the summer and winter solstices and the vernal and autumnal equinoxes have been bound up with the idea of sowing and reaping, death and rebirth, year's end and year's opening; at such times it was traditionally believed that supernatural forces were in control and should be propitiated.
