Our Earth, our Solar system, other planets in our Solar system & many other types of Solar systems are there in this Galaxy of ours. All these planets including earth, moon etc. in our Solar system & other solar systems are there in this Material World. Our earth is illumined by the Sun. Similarly other planets like Mars, Jupiter, Mercury, Saturn etc. are all illumined by the Sun, as all are part of the Sun's solar system. Sun is the external body which illumines all these planets & these planets have to depend on some outer body like Sun to have their existence / life. Similarly other Solar systems are there, in which also other Suns sustain their planets. In Material World no single planet is self illumined, that means all planets have to depend upon some other celestial body like Sun to illumine them & give life to them.
In Spiritual Worlds it is not like that. Spiritual Worlds are abodes of God Himself & there is no need for any external body like Sun to illumine it. These are illumined by the power & Grace of God Himself, that is the reason that these Planets / abodes of God are Self Illumined in nature. These planets are full of beauty & there is no disease etc. on those abodes. A person's soul always remains in Blissful & Happy state over there. These Spiritual Worlds are beyond the Material Worlds. Below verse of Bhagwat Gita explains that these abodes are Self Illumined in nature.
"na tad bhasayate suryo
na sasanko na pavakah
yad gatva na nivartante
tad dhama paramam mama" (Bhagwat Gita: Chapter Fifteen verse 6)
"Sri Krishna said: O Arjuna, That God abode of Mine is not illumined by the Sun or Moon, nor by fire or electricity as these are Self Illumined in nature. Those who reach there never return to this material world again."
Now how we can attain to these Spiritual Worlds? If we believe in God & invoke Him by prayers daily, then He shall certainly come to our rescue, as He always comes to the rescue of His devotees. So by the devotion, prayer to the Almighty, He shall arrange for our stay in the beautiful Spiritual Worlds which are abodes of God Himself.
God Himself is declaring below in Bhagwad-Gita that, a person can come to Him through devotion.
"man-mana bhava mad-bhakto
mad-yaji mam namaskuru
mam evaishyasi satyam te
pratijane priyo ’si me" (Bhagwat Gita: Chapter Eighteen verse 65)
"Lord Sri Krishna said: O Arjuna, Always think of Me, become My devotee, worship Me and offer your homage unto Me. Thus you will come to Me without fail. I promise you this because you are My devotee."
As God is the Supreme Soul from whom all these souls have emanated, so worshipping him constantly, one shall be established in the soul & shall attain a blissful life.
"bhaktya mam abhijanati
yavan yas chasmi tattvatah
tato mam tattvato jnatva
visate tad-anantaram" (Bhagwat Gita: Chapter Eighteen verse 55)
"Sri Krishna said: O Arjuna, One can understand Me as I am, as the Supreme Personality of Godhead, only by devotional service. And when one is in full consciousness of Me by such devotion, he can enter into the kingdom of God."
So let's be devoted to God as worshiping Him we shall be able to transcend this Material World & shall be able to enter the beautiful Spiritual World which is abode of God Himself.
Jai Sri Krishna