HELI'ACAL, a. [L. heliacus; Gr. the sun.]
Emerging from the light of the sun, or passing into it. The heliacal rising of a star, is when, after being in conjunction with it and invisible, it emerges from the light so as to be visible in the morning before sunrising. On the contrary, the heliacal setting of a star, is when the sun approaches so near as to render it invisible by its superior splendor.
