You could try making the planets spin by setting up an animation in the Materials Lab.  For each sphere, open the Mat Lab, set the materials you wish to use on the sphere, probably, an imported texture may be best here.  (see skiwillgee's excellent mini tut, making image based materials for Bryce ) then set the timeline at the bottom of the Mat Lab window so that the texture image rotates through 360 degrees. 

I've not tried it with more than one sphere, but I wonder if you could even get the planets to spin at different rates. Anyway, this should free up your animation time line to concentrate on the planetary orbits.

Good luck. Hope to see a link on here to your work if it's successful.

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As a writer, I control the lives of millions. Whole worlds can be destroyed by typing the correct sequence of letters on my keyboard.

Robert A. Read