God made the sun, moon and stars as a mode to communicate to the Jewish people His appointed times (Feasts, Moadim).
“And God said, “Let there be lights in the vault of the sky to separate the day from the night, and let them serve as signs to mark sacred times, and days and years” Genesis 1:14
Jesus likewise shared that there would be signs in the heavens before his second coming as a guide to make us aware of the end times. The signs aid us to determine the nearness of his return and to pinpoint time periods before and during the tribulation (Daniels 70th Week).
A great sign appeared in heaven: a woman clothed with the sun, with the moon under her feet and a crown of twelve stars on her head. 2 She was pregnant and cried out in pain as she was about to give birth.
This sign will appear in the heavens above Israel on September 23, 2017. According to scripture this sign will take place during the middle of the Tribulation which is 3 ½ years (1260 days).