The spiritual sky is beyond the material sky

 

„One mustard seed is calculated to be a universe itself. In one of the universes, in which we are now living, the number of planets cannot be counted by human energy, and so how can we think of the sum total in all the universes, which are compared to a bucketful of mustard seeds? And the planets in the spiritual sky are at least three times the number of those in the material sky. Such planets, being spiritual, are in fact transcendental to the material modes; therefore they are constituted in the mode of unalloyed goodness only. The conception of spiritual bliss (brahmānanda) is fully present in those planets. Each of them is eternal, indestructible and free from all kinds of inebrieties experienced in the material world. Each of them is self-illuminating and more powerfully dazzling than (if we can imagine) the total sunshine of millions of mundane suns. The inhabitants of those planets are liberated from birth, death, old age and diseases and have full knowledge of everything; they are all godly and free from all sorts of material hankerings.” (SB 2.6.18, Purport)

„Not even all of the material world is manifested before us. Our senses are so imperfect that we cannot even see all of the stars within this material universe. In Vedic literature we can receive much information about all the planets, and we can believe it or not believe it. All of the important planets are described in Vedic literatures, especially Śrīmad-Bhāgavatam, and the spiritual world, which is beyond this material sky, is described as avyakta, unmanifested. One should desire and hanker after that supreme kingdom, for when one attains that kingdom, he does not have to return to this material world.

Next, one may raise the question of how one goes about approaching that abode of the Supreme Lord. Information of this is given in the Eighth Chapter. It is said there:

anta-kāle ca mām eva smaran muktvā kalevaram

yaḥ prayāti sa mad-bhāvam yāti nāsty atra saṁśayaḥ

"Anyone who quits his body, at the end of life, remembering Me, attains immediately to My nature; and there is no doubt of this." (BG. 8.5) One who thinks of Kṛṣṇa at the time of his death goes to Kṛṣṇa. One must remember the form of Kṛṣṇa; if he quits his body thinking of this form, he approaches the spiritual kingdom. Mad-bhāvaṁ refers to the supreme nature of the Supreme Being. The Supreme Being is sac-cid-ānanda-vigraha - eternal, full of knowledge and bliss. Our present body is not sac-cid-ānanda. It is asat, not sat. It is not eternal; it is perishable. It is not cit, full of knowledge, but it is full of ignorance. We have no knowledge of the spiritual kingdom, nor do we even have perfect knowledge of this material world where there are so many things unknown to us. The body is also nirānanda; instead of being full of bliss it is full of misery. All of the miseries we experience in the material world arise from the body, but one who leaves this body thinking of the Supreme Personality of Godhead at once attains a sac-cid-ānanda body, as is promised in this fifth verse of the Eighth Chapter where Lord Kṛṣṇa says, "He attains My nature."  „

(BG Introduction)