God Uses The Sky For Signs For Us.

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And immediately after the affliction/tribulation of thoses days the sun will be darkened and the moon will not give her light,and the stars will fall from the heaven, and the powers of the heavens will be shaken.
And then the sign of the Son of man will appear in the heavens; And then all the tribes of the land will wail,
and they will see the Son of man comeing on the clouds of heaven with power and much glory.
---Daniel 7:13
Immediately after the tribulation of those days shall the sun be darkened, and the moon shall not give her light, and the stars shall fall from heaven, and the powers of the heavens shall be shaken: And then shall appear the sign of the Son of man in heaven: and then shall all the tribes of the earth mourn, and they shall see the Son of man coming in the clouds of heaven with power and great glory.
Matthew 24:29

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And what I say unto you I say unto all, Watch.
Mark 13:37