Venus Equilateral (collection)

A Venus Equilateral is a rare near-equilateral triangle formation of Earth, Venus, and the Sun in their orbital motions around the Sun. Although the orbits of Earth and Venus are nearly circular, and not perfectly coplanar, Venus's orbital period is approximately 0.615 Earth years, resulting in a roughly 8:13 orbital resonance. This resonance leads to the apparent relationship where Venus appears to return to approximately the same spot in Earth's sky every five synodic periods, which corresponds to about eight Earth years.

As Earth and Venus orbit, their relative positions as viewed from the Sun will occasionally form a triangle. The term "Venus Equilateral" specifically refers to instances when this Earth-Venus-Sun triangle is close to equilateral; meaning all three sides of the triangle are approximately equal in length. Because the orbits are not perfectly circular or coplanar, a truly perfect equilateral triangle is never achieved, but near-equilateral configurations do occur periodically. These occurrences are not strictly cyclical because of perturbations to the orbits caused by other planets.

The term "Venus Equilateral" primarily denotes a geometrical phenomenon arising from the interplay of orbital mechanics. While visually interesting, it doesn't have direct practical implications for astronomy beyond illustrating orbital relationships. It is primarily a curiosity within the field of celestial mechanics and has captured the attention of those interested in astronomical patterns and resonances. Calculating the exact moments of these near-equilateral configurations requires sophisticated orbital calculations.