User:Aeluwas/Antisolar point

The antisolar point is the imaginary point on the celestial sphere exactly opposite the Sun.

Occasionally, during sunset or sunrise, anticrepuscular rays can be seen to converge at the antisolar point. Also, on a moonless night away from city lights, it is often possible to see the gegenschein at that point, arising from the back-scattering of light by interplanetary dust. In astronomy, when the moon or planets are in opposition, they are found close to the antisolar point. The antisolar point is the center of rainbows, and can be easily found on a sunny day: it it located at the shadow of one's head.

Anthelic point
The anthelic point is often used as a synonym for the antisolar point, but the two should be differentiated. While the antisolar point is directly opposite the sun, always below the horizon when the sun is up, the anthelic point is opposite but at the same altitude as the sun, and is therefore located on the parhelic circle. There are several halo phenomena that are centered on or converge on the anthelic point, such as the anthelion, Wegener arcs, Tricker arcs and the parhelic circle itself.

Notes and references
Category:Spherical astronomy