"And God said, 'Let there be lights in the firmament of the heaven to divide the day from the night; and let them be for SIGNS, and for seasons, and for days, and years:'" (Genesis 1:14).
Jesus said this in answer to the questions about the end of the age and His second coming:
"And GREAT earthquakes shall be in divers places, and famines, and pestilences; and FEARFUL SIGHTS and GREAT SIGNS shall there be from HEAVEN" (Luke 21:11).
"And there shall be SIGNS in the SUN, and in the MOON, and in the STARS; and upon the earth distress of nations, with perplexity; the sea and the waves roaring (tsunamis); Men's hearts failing them for fear, and for looking after those things which are coming on the earth: for the powers of heaven shall be shaken. And then shall they see the SON of man COMING in a cloud with power and great glory. And when these things BEGIN to come to pass, then look up, and lift up your heads; for your redemption draweth nigh" (Luke 21:25-28).