March 1, 2004
A: FROM MENTOR JOAN LUSK IN RI
The ecliptic is the plane defined by the earth's orbit around the
sun. The sun itself, at the center of the orbit, is in the ecliptic,
and so are the moon and the planets. The constellations of the
zodiac straddle this plane - hence astrologers talk about the sun
being "in" one of these constellations as viewed from the earth,
passing through them in a yearly cycle.
http://reference.allrefer.com/encyclopedia/E/ecliptic.html