Orbit of Mars

Mars has an orbit with a semimajor axis of 1.524 astronomical units (228 million km) (12.673 light minutes), and an eccentricity of 0.0934.

[10] Until the work of Johannes Kepler (1571–1630), a German astronomer, the prevailing belief was that the Sun and planets orbited the Earth.

In 1543, Nicolaus Copernicus had proposed that all the planets orbited in circles around the Sun, but his theory did not give very satisfactory predictions and was largely ignored.

An equation in Astronomical Algorithms that assumes an unperturbed elliptical orbit predicts the perihelion and aphelion times with an error of "a few hours".

Formulas for computing position straight from orbital elements typically do not provide or need corrections for the effects of other planets.

E. Myles Standish wrote: "Classical ephemerides over the past centuries have been based entirely upon optical observations:almost exclusively, meridian circle transit timings.

(8.5.1 page 10) For DE405, created in 1995, optical observations were dropped and as he wrote "initial conditions for the inner four planets were adjusted to ranging data primarily…"[15] The error in DE405 is known to be about 2 km and is now sub-kilometer.

[17] But improving the model of the asteroid belt is of great concern to those requiring or attempting to provide the highest-accuracy ephemerides.