Endless are the planets for each fixed star, and each of these planets is but one of the worlds of the Creator. Who is able to number the hosts of your Lord on those planets or enumerate the crafts of His servants on them?
Baha’u’llah, quoted in Amr va Khalq, 1:137.
As for your question about planets in which you ask if the planets that circle around fixed suns through the power of attraction are creations like terrestrial creations, know that in the explicit text of the Qur’an God set forth a clear, sufficient statement that will delight the ears that hear it. He said: “…the creation of the heavens and the earth and the creatures that He scattered among them” (Q 42:29). He explicitly states that there are beings in them that move according to the divine Will….As for the specific character of those beings–whether they are like terrestrial beings, or airy, fiery beings, or fiery beings–their natures differ and the balance of their elements diverge. The composition of those beings differs according to their essences.
`Abdu’l-Baha, quoted in Amr va Khalq, 1:145-6