Mankind has always been fascinated with the heavens: their beauties, their mysteries, their movements, and their surprises. Early on in man's history, after years of observation and record keeping, the learned discovered that—with certain exceptions—the movements of the heavenly bodies could be predicted, as could phenomena like eclipses, comets, and meteor showers. To them, what occurred on the dark canvas of space revealed creation's design, order, and perfection. As David wrote, "The heavens declare the glory of God; and the firmament shows His handiwork" (Psalm 19:1).
Despite the rational, scientific understanding of most celestial happenings, sudden changes in the normally placid, soothing nighttime sky can cause wonder and even panic. Comets, long thought to portend world-changing events, have been known to ignite terrors in superstitious people. Eclipses of the sun can spur the unenlightened to believe the end of the world has come, as can a "bloody" moon. From the earliest times, men and women perverted even the regular movements of heavenly bodies into astrology, and millions still consult their readings daily. God warns, "Do not learn the way of the Gentiles; do not be dismayed at the signs of heaven, for the Gentiles are dismayed at them" (Jeremiah 10:2).
Yet, God Himself uses heavenly phenomena as signs of momentous events. Perhaps the most famous is the "Star of Bethlehem," which guided the wise men to their audience with the young King of the Jews (Matthew 2:1-2, 9-11). Though this "star" was most likely an angel standing as a beacon for the magi to follow, many have postulated "natural" explanations such as comets and supernovae. The Ninth Plague on Egypt (Exodus 10:21-23), Joshua's Long Day (Joshua 10:12-14), Hezekiah's Sundial (II Kings 20:8-11), and the darkness during Jesus' crucifixion (Matthew 27:45) all involved aberrations of expected solar behavior. All signaled major movements in God's plan.
The sixth seal also involves heavenly bodies doing the unexpected: The sun darkens, the moon turns blood-red, the stars fall, and the sky itself rolls up like a scroll. Not only do these terrifying cosmic wonders signal the beginning of the Day of the Lord, but they, like the previous five seals, also serve as judgments against sinful mankind on planet Earth.