Anti-solar point

The point on the rainbow axis around which the arcs of a rainbow appear is called the anti-solar point.

• An imaginary straight line can always be drawn that passes through the Sun, the eyes of an observer and the anti-solar point – the geometric centre of a rainbow.
• The idea that a rainbow has a centre corresponds with what an observer sees in real-life.
• Seen in side elevation the centre-point of a rainbow is called the anti-solar point.
• ‘Anti’, because it is opposite the Sun with respect to the location of an observer.
• Unless seen from the air, the anti-solar point is always below the horizon.
• The centre of a secondary rainbow is always on the same axis as the primary bow and shares the same anti-solar point.
• First, second, fifth and sixth-order bows all share the same anti-solar point.