What is Venus's orbital eccentricity approximately?

Venus’s orbital eccentricity is approximately 0.007, more precisely about 0.0068. Eccentricity measures how much an orbit departs from a perfect circle: 0 represents a circle, while larger values indicate a more elongated ellipse.

Because Venus’s eccentricity is so small, its orbit is nearly circular. Its distance from the Sun changes only from about 0.718 AU at perihelion to about 0.728 AU at aphelion, a difference of roughly 1.46 million kilometres. Venus has the least eccentric planetary orbit in the Solar System today.

The answer is often confused with Earth’s eccentricity, about 0.017, or Mars’s, about 0.093. Mercury’s orbit is much more elongated, with an eccentricity near 0.206. These differences affect how strongly a planet’s solar heating changes over an orbit.

A low eccentricity does not mean Venus travels at constant speed. Under Kepler’s laws, Venus moves slightly faster when nearer the Sun and slightly slower when farther away. Its nearly circular path is a present-day orbital condition; simulations suggest Venus’s ancient eccentricity may have been substantially higher.