This is a polar grid centered on the sun, and along the ecliptic. Powers of ten up to about 1 LY. The smallest radial spacings are in millions of km. Angle spacings are 10?°. Usefull to study the planets excentricities, and orbital inclinations. You need to zoom-in and out to see the nice scaling effect. Of course, this is the same technology as Selden's graticules.

Download link to the addon (tiny zip file !) :
http://nho.ohn.free.fr/celestia/Cham/PolarGrid.zip