HARVEST MOON

1. That point of intersection of the ecliptic and the celestial equator occupied by the sun as it changes from north to south declination, on or about September 23. Also called SEPTEM- BER EQUINOX, FIRST POINT OF LIBRA. 2. The instant the sun reaches the point of zero declination when crossing the celestial equator from north to south

The various appearances of the moon during differ- ent parts of the synodical month. The cycle begins with new moon or change of the moon at conjunction. The visible part of the waxing moon increases in size during the first half of the cycle until full moon appears at opposition, after which the visible part of the waning moon decreases for the remainder of the cycle. First quarter occurs when the waxing moon is at east quadrature; last quarter when the waning moon is at west quadrature. From last quarter to new and from new to first quarter the moon is crescent; from first quarter to full and from full to last quarter it is gibbous. The elapsed time, usually expressed in days, since the last new moon is called age of the moon. The full moon occurring nearest the autumnal equinox is called harvest moon; the next full moon, hunter’s moon.

The season in the Northern Hemisphere which begins astronomically at the vernal equinox and ends at the summer solstice. In the Southern Hemisphere the limits are the autumnal equinox and the winter solstice.

1. The angular distance in the ecliptic from the vernal equinox to the ascending node of the orbit. 2. The angular distance, always measured eastward, in the plane of the celestial equator from Greenwich through 360°.

An orbital element that specifies the orientation of an orbit; it is a broken angle consisting of the angular distance in the ecliptic from the vernal equinox to the ascending node of the orbit plus the angular distance in the orbital plane from the ascend- ing node to the pericenter, i.e. the sum of the longitude of the ascending node and the argument of pericenter.

Angular distance east of the vernal equinox, along the ecliptic; the arc of the ecliptic or the angle at the ecliptic pole between the circle of latitude of the vernal equinox at the circle of latitude of

Zero hours local sidereal time, or the instant the vernal equinox is over the upper branch of the local meridian. Local sidereal noon at the Greenwich meridian is called Greenwich sidereal noon.

The great circle of the celestial sphere through the celestial poles and the equinoxes; the hour circle of the vernal equinox

1. One of the two points of intersection of the ecliptic and celestial equator, occupied by the su

Of or pertaining to an equinox or the equinoxes