There seems to be a problem with the elliptical orbit code that puts
objects in incorrect positions.
For example, if you take current JPL data for Ceres and add this to
Stellarium in elliptical orbit format you get a position pretty far off
from what you get using the comet_orbit function.
At least for Ceres, you can get the position corrected by subtracting 90
degrees from the orbit_AscendingNode, orbit_LongOfPericenter, and
There is an unresolved issue in Planet::draw_sphere about rotating the
texture 90 degrees that could be related.
I wondered if this might trigger any ideas of where to concentrate?
Here is the (uncorrected) elliptical data:
name = Ceres-ell
parent = Sun
radius = 470
oblateness = 0.0
albedo = 0.113
lighting = true
sidereal_period = 1680.15
halo = true
color = 1.0,1.0,1.0
tex_halo = star16x16.png
tex_map = nomap.png
coord_func = ell_orbit
orbit_Epoch = 2452600.500000000
orbit_Period = 1680.224536101142
orbit_SemiMajorAxis = 413781759.8318673
orbit_Eccentricity = 0.07927998653797770
orbit_Inclination = 100.58356977077303
orbit_AscendingNode = 260.48265607209696
orbit_LongOfPericenter = 154.52621121276100000
orbit_MeanLongitude = 386.59322373625800000