In the Quran the sky is referred to as-sama’,as-samawat & as-sama ad-dunya.

a.What is the best definition of the three terms mentioned that is given by mufassirs
b.What is their relationship between each other?
c.What would each of the term refer to, in our present scientific understanding of the Universe?
d.Also in 3:133 it is mentioned that the heaven is as big as as-samawatu wal ardh whereas in 57:21 it as-sama i wal ardh .Why the difference?
e.what is meant by "baina samawati wal ardh"-what is between heavens and earth?

a. The best definition of the three terms mentioned, as given by mufassirs (Quranic commentators), can vary based on their interpretations and the context in which they are used. However, generally speaking:

- As-sama’: This term refers to the sky or the heavens. It is often understood as the physical sky or the celestial realm.

- As-samawat: This term is the plural of as-sama’. It emphasizes the vastness and magnitude of the heavens, indicating multiple levels or layers of the sky.

- As-sama ad-dunya: This term specifically refers to the closest or nearest heaven, often understood as the visible sky from the Earth's perspective.

b. The relationship between these terms can be understood as a hierarchy or layered structure. As-sama' can be seen as the general term for the sky or heavens, while as-samawat represents the multiple levels or layers of the sky, emphasizing their vastness. As-sama ad-dunya, being the closest heaven, can be considered as the first or lowest layer of the celestial realm.

c. In our present scientific understanding of the universe:

- As-sama’: From a scientific perspective, as-sama’ can be interpreted as the entire expanse of the universe or the cosmos, including galaxies, stars, and all celestial bodies.

- As-samawat: The plural form of as-sama’ can be seen as representing the various layers or components of the universe, such as galaxies, clusters of galaxies, and other cosmic structures.

- As-sama ad-dunya: This term can correspond to the Earth's atmosphere and the visible sky from our perspective. It includes the troposphere, stratosphere, mesosphere, thermosphere, and exosphere.

d. The difference between the mention of the heavens and the earth in different verses can be attributed to the variations in the linguistic style of the Quran. In some verses, the phrase "as-samawatu wal ardh" (the heavens and the earth) is used to express the totality of the universe, emphasizing its vastness. On the other hand, the phrase "as-sama i wal ardh" (the heaven and the earth) is used to reference the visible sky or the celestial realm in a more specific or contextual manner.

e. The phrase "baina samawati wal ardh" (between the heavens and the earth) refers to the space or the expanse that exists between the celestial realm and the Earth's surface. It suggests the existence of a realm beyond our atmosphere and the celestial bodies that are observable from Earth. In a scientific context, it can indicate the vastness of space, which extends beyond our immediate cosmic neighborhood.