noun
orbital eccentricity
Technical term in astronomy describing how much an orbit deviates from a perfect circle.
この惑星の軌道離心率は非常に小さいため、ほぼ円軌道を描いている。
Because this planet's orbital eccentricity is very small, it follows a nearly circular orbit.
軌道離心率が大きいほど、楕円軌道は細長くなる。
The larger the orbital eccentricity, the more elongated the elliptical orbit becomes.
Compound of 軌道 (orbit) and 離心率 (eccentricity).