It is because those planets (the Vaikuntha planets and the Goloka Vrndavana planet) are self-illuminating that all effulgence has become possible, and whatever there is that is dazzling is due to the reflection of that sva-dhama

Expressions researched:
"it is because those planets are self-illuminating that all effulgence has become possible, and whatever there is that is dazzling is due to the reflection of that sva-dhāma"

Srimad-Bhagavatam

SB Canto 2

The Lord's sva-dhāma does not require any sunlight or moonlight or electricity for illumination. That dhāma, or place, is supreme, and whoever goes there never comes back to this material world.

The Vaikuṇṭha planets and the Goloka Vṛndāvana planet are all self-illuminating, and the rays scattered by those sva-dhāma of the Lord constitute the existence of the brahmajyoti.

SB 2.4.14, Translation and Purport

Let me offer my respectful obeisances unto Him who is the associate of the members of the Yadu dynasty and who is always a problem for the nondevotees. He is the supreme enjoyer of both the material and spiritual worlds, yet He enjoys His own abode in the spiritual sky. There is no one equal to Him because His transcendental opulence is immeasurable.

There are two sides of the transcendental manifestations of the Supreme Lord, Śrī Kṛṣṇa. For the pure devotees He is the constant companion, as in the case of His becoming one of the family members of the Yadu dynasty, or His becoming the friend of Arjuna, or His becoming the associate neighbor of the inhabitants of Vṛndāvana, as the son of Nanda-Yaśodā, the friend of Sudāmā, Śrīdāmā and Madhumaṅgala, or the lover of the damsels of Vrajabhūmi, etc.