Eccentricity of the Earth's orbit around the Sun. The fluctuation between a nearly circular and elliptical orbit drives cyclic changes in the Earth's environment, including the global carbon cycle.

The maximum eccentricity possible is 1, which forms not a closed orbit but a parabola, meaning the object will never complete a full orbit but instead be flung off into space.) The difference ...

A 128-minute orbit, according to Kepler's third law, works out to a semi-major axis of 8,413 km (5,228 mi). Such an object with less than 0.25 eccentricity (a roughly circular orbit), therefore ...