So far the Avataras are concerned there are two types. One is called nitya and the other is called naimittic. Nitya means eternal and namittic Avataras appear for some specific function in the material worlds. Nitya Avataras have their eternal abodes in the spiritual sky from which they may sometimes descend to the material worlds, but naimittic Avataras are expansions of Nitya Avataras for some timely purpose. So the non-human forms of Avataras do not have their planets in the spiritual sky.
Letter to Ekayani Dasi, 25 July, 1970