Could it be that the planets are castaway heads.

THE CURSE

May they never
Return home at night...

May you have no part of eventide,
May you have no room of your own,
Nor road, nor return.
May your days be all exactly the same,
Five Fridays in a row,
Always an unlucky Tuesday,
No Sunday,
May you have no more little worries,
Tears or inspiration,
For you yourself are the greatest worry on earth:

Prisoner!

Handcuffs weigh much more than gravestones.

(from "Gratitude")

I'm a bloodletter, not a politician," Nyx said. "I just take off heads.

You're on Earth. There's no cure for that.

Planets move in ellipses with the Sun at one focus.