Surah 37. As-Saffat

5"Lower heaven" : The nearer heaven which can be seen with the naked eye, without the help of a telescope. The worlds beyond which can be seen through the telescopes of different powers, and the worlds which have not so far been observed through any moans, are the distant heavens. In this connection, one should also note that "sama " is not something definite and determined, but man generally has been using this word and its other synonyms for the heavens since the earliest times.

6That is, "Heaven is not merely empty space so that anyone who likes may enter it, but it has been fortified strongly, and its different regions have been bounded by such strong barriers that it is impossible for any rebel satan to exceed them. Every star and planet in the universe has its own circle and sphere escaping from which is as difficult as entering it. With the naked eye one can only see empty space, but, in reality, there are countless regions in space which have been even more strongly fortified and protected than they could be by steel walls. One can imagine and estimate the strength of these barriers by the difficulties man is experiencing in the way of reaching the moon, which is our nearest neighbor in space. Similar difficulties prevent the other creation of the earth, the jinns, from ascending towards the heavens.

7To understand this one should keep in view the fact that in the time of the Holy Prophet, soothsaying was in great vogue in Arabia. The soothsayers used to make predictions, give news of the unseen, tell the whereabouts of the lost properties and articles, and the people used to visit them to know the events of their past and future lives. These soothsayers claimed that they had some jinns and satans under their control, who brought them all sorts of news. In this environment when the Holy Prophet was appointed to Prophethood, and he began to recite the verses of the Qur'an, which described the past history and contained news of the future, and also stated that an angel brought him these verses, his opponents immediately branded him a soothsayer and started telling others that, like the other soothsayers, he too was associated with a satan, who brought him news from the heavens, which he presented as revelations from Allah. To refute this accusation, Allah says: "The satans have no access to heaven. They have no power to hear the conversations of the angels and bring its news for others; if by chance a little of it enters the ear of a satan, and he tries to bring it down, he is followed by a flashing flame." In other words, it means: "The grand system of the universe, which is functioning under the agency of the angels has been firmly guarded and secured against every interference of the satans. Not to speak of interfering in it, they do not even have the power to obtain any kind of information about it. " (For further explanation, see AI-Hijr: 17-18 and the E.N's thereof).