The living entities are traveling from one planet to another, but it is not that we can go to any planet we like merely by a mechanical arrangement. If we desire to go to other planets, there is a process for going there. This is also mentioned: yānti deva-vratā devān pitṟn yānti pitṛ-vratāḥ (BG 9.25). No mechanical arrangement is necessary if we want interplanetary travel. The Gītā instructs: yānti deva-vratā devān. The moon, the sun and higher planets are called Svargaloka. There are three different statuses of planets: higher, middle and lower planetary systems. The earth belongs to the middle planetary system. Bhagavad-gītā informs us how to travel to the higher planetary systems (Devaloka) with a very simple formula: yānti deva-vratā devān. One need only worship the particular demigod of that particular planet and in that way go to the moon, the sun or any of the higher planetary systems.
Yet Bhagavad-gītā does not advise us to go to any of the planets in this material world, because even if we go to Brahmaloka, the highest planet, through some sort of mechanical contrivance by maybe traveling for forty thousand years (and who would live that long?), we will still find the material inconveniences of birth, death, disease and old age. But one who wants to approach the supreme planet, Kṛṣṇaloka, or any of the other planets within the spiritual sky, will not meet with these material inconveniences. Amongst all of the planets in the spiritual sky there is one supreme planet called Goloka Vṛndāvana, which is the original planet in the abode of the original Personality of Godhead Śrī Kṛṣṇa. All of this information is given in Bhagavad-gītā, and we are given through its instruction information how to leave the material world and begin a truly blissful life in the spiritual sky.
In the Fifteenth Chapter of the Bhagavad-gītā, the real picture of the material world is given. It is said there:
- ūrdhva-mūlam adhaḥ-śākham
- aśvatthaṁ prāhur avyayam
- chandāṁsi yasya parṇāni
- yas taṁ veda sa veda-vit
Here the material world is described as a tree whose roots are upwards and branches are below. We have experience of a tree whose roots are upward: if one stands on the bank of a river or any reservoir of water, he can see that the trees reflected in the water are upside down. The branches go downward and the roots upward. Similarly, this material world is a reflection of the spiritual world. The material world is but a shadow of reality. In the shadow there is no reality or substantiality, but from the shadow we can understand that there are substance and reality. In the desert there is no water, but the mirage suggests that there is such a thing as water. In the material world there is no water, there is no happiness, but the real water of actual happiness is there in the spiritual world.
The Lord suggests that we attain the spiritual world in the following manner (BG 15.5):
- nirmāna-mohā jita-saṅga-doṣā
- adhyātma-nityā vinivṛtta-kāmāḥ
- dvandvair vimuktāḥ sukha-duḥkha-saṁjñair
- gacchanty amūḍhāḥ padam avyayaṁ tat
That padam avyayam, or eternal kingdom, can be reached by one who is nirmāna-moha. What does this mean? We are after designations. Someone wants to become "sir," someone wants to become "lord," someone wants to become the president or a rich man or a king or something else. As long as we are attached to these designations, we are attached to the body, because designations belong to the body. But we are not these bodies, and realizing this is the first stage in spiritual realization. We are associated with the three modes of material nature, but we must become detached through devotional service to the Lord. If we are not attached to devotional service to the Lord, then we cannot become detached from the modes of material nature. Designations and attachments are due to our lust and desire, our wanting to lord it over the material nature. As long as we do not give up this propensity of lording it over material nature, there is no possibility of returning to the kingdom of the Supreme, the sanātana-dhāma. That eternal kingdom, which is never destroyed, can be approached by one who is not bewildered by the attractions of false material enjoyments, who is situated in the service of the Supreme Lord. One so situated can easily approach that supreme abode.
Elsewhere in the Gītā (8.21) it is stated:
- avyakto 'kṣara ity uktas
- tam āhuḥ paramāṁ gatim
- yaṁ prāpya na nivartante
- tad dhāma paramaṁ mama
Avyakta means unmanifested. 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.