Lord Visnu, has assumed the form of Sisumara in the seventh heaven, which is situated in the topmost level of the universe. All the other planets, beginning with the sun, exist under the shelter of this Sisumara planetary system

Expressions researched:
"Lord Visnu" |"has assumed the form of Sisumara in the seventh heaven, which is situated in the topmost level of the universe. All the other planets, beginning with the sun, exist under the shelter of this Sisumara planetary system"

SB Canto 5

Lord Viṣṇu, who is the source of knowledge and transcendental bliss, has assumed the form of Śiśumāra in the seventh heaven, which is situated in the topmost level of the universe. All the other planets, beginning with the sun, exist under the shelter of this Śiśumāra planetary system.

SB 5.22.17, Translation and Purport:

Situated 8,800,000 miles above Saturn, or 20,800,000 miles above earth, are the seven saintly sages, who are always thinking of the well-being of the inhabitants of the universe. They circumambulate the supreme abode of Lord Viṣṇu, known as Dhruvaloka, the polestar.

Śrīla Madhvācārya quotes the following verse from the Brahmāṇḍa Purāṇa:

jñānānandātmano viṣṇuḥ

śiśumāra-vapuṣy atha

ūrdhva-lokeṣu sa vyāpta

ādityādyās tad-āśritā

Lord Viṣṇu, who is the source of knowledge and transcendental bliss, has assumed the form of Śiśumāra in the seventh heaven, which is situated in the topmost level of the universe. All the other planets, beginning with the sun, exist under the shelter of this Śiśumāra planetary system.