The moon and stars are the lesser sources of illumination, the religious leaders and teachers, who should guide and inspire the people.

When it is said that the moon shall not give her light or shall be turned into blood, and the stars shall fall from heaven, it is indicated that the leaders of the churches shall become debased, engaging in strife and contention, and the priests shall become worldly minded, concerned about earthly instead of heavenly things.
The meaning of these prophecies is not exhausted by one explanation, however, and there are other senses in which these symbols can be interpreted.

Baha'u'llah says that in another sense the words "sun," "moon," and "stars" are applied to the ordinances and instructions enacted in every religion.

As in every subsequent Manifestation the ceremonies, forms, customs and instructions of the preceding Manifestations are changed in accordance with the requirements of the times, so, in this sense the sun and moon are changed and the stars dispersed.
In many cases the literal fulfillment of these prophecies in the outward sense would be absurd or impossible; for example, the moon being turned into blood or the stars falling upon the earth.

The least of the visible stars is many thousand times larger than the earth, and were one to fall on the earth there would be no earth left for another to fall on! In other cases, however, there is a material as well as a spiritual fulfillment.
For example, the Holy Land did literally become desert and desolate during many centuries, as foretold by the prophets, but already, in the Day of Resurrection, it is beginning to "rejoice and blossom as the rose," as Isaiah foretold.