One of my favorite movies when I was a kid was Day of the Triffids. In this 1963 British film, the earth experiences an unusual meteor shower. Everyone who watched the meteors were struck blind, and for reasons not sufficiently explained in the film a rare type of plant (a “triffid”) mutated into a shambling stalk of killer asparagus. The star of the film, Howard Keel, was recovering from eye surgery at the time, so he was left to survive in post-apocalyptic England, dodging escaped prisoners and killer vegetables. Not one of the great plot lines in film history, but it made me wary of watching meteor showers when I was eight years old. In fact, a meteor shower cannot really strike you blind.
Like the imaginary Day of the Triffids, the coming “Great American Eclipse” has generated more weirdness than I would have expected. For example, officials in South Carolina are concerned about “possible ‘Lizard Man,’ ‘Bigfoot’ sightings in during eclipse.” There is even a “Total Eclipse Safety Tips” page recommending residents “Fill your car up with gas and buy groceries before the weekend.” To be fair, the reason is not particularly apocalyptic; officials are worried about a huge influx of visitors for Eclipse Day. Even more fringe, the eclipse will “reveals exact date Nibiru will destroy Earth” (spoiler: September 23, 2017).
Prophecy-obsessed Christians have latched onto the eclipse as well. Anne Graham Lotz, for example, speculates the solar eclipse is a sign of impending judgment on America. She starts her brief comments by citing Joel 2:31. In that text the sun is darkened before the great day of the Lord. Along with the blood-moon delusions of a few years ago, this obsession with regular astronomical phenomenon is the result of a combination of poor biblical exegesis and a lack of understanding of science.
First, a solar eclipse is a normal and predictable event. There is nothing about this even which is unusual or supernatural. Simply put, the moon blocks light from the sun. This is a very predictable event. There was a solar eclipse March 8/9, 2016 visible in Indonesia (no apocalyptic judgment happened), and there will be another solar eclipse July 2, 2019 visible in South America. You can visit Time and Date to find out dates for lunar or solar eclipse in your area.
Second, any biblical text which mentions the “sun darkened” is not talking about a regular, normal eclipse. I mention here only two examples. In the Joel 2:31 passage Lotz cites, the sun is darkened as a part of apocalyptic events associated with the Day of the Lord. In the immediate context Joel refers to the Holy Spirit as “poured out” on all people. This is a standard way of referring to the New Covenant (for example, Isaiah 35; Jer 33:31-33). The “darkening of the sun” could refer (literally) to the sun darkened during God’s wrath on Jerusalem in 586 B.C., or (more figuratively) to the abasement of the sun and moon as spiritual forces, gods, etc. Either way, it is not a natural, predictable phenomenon.
A second example of unnatural darkness is the three hours of darkness during the crucifixion (Mark 15:33). This cannot be an eclipse since it lasts far too long and is localized to “the land,” probably just Jerusalem or Judea. Although the darkness can be explained theologically in several different ways, it is not a natural, predictable phenomenon.
Third, the Bible must be read in its cultural context. The ancient world did not fully understand what an eclipse was and often thought they were signs from the gods. For example, according to Herodotus an eclipse occurred during a war between the Medes and the Lydians; both sides were so terrified by the sign they immediately signed a peace treaty (Hist. 1.73-74). The eclipse was allegedly predicted Thales of Miletus.
Similarly, in 1503 Columbus accurately predicted a lunar eclipse and the red moon and used this prediction to pacify the local Jamaican islanders. Thucydides 1.23.3, a listed eclipses along with earthquakes, droughts, famines, and pestilence affected the Athenians during the Peloponnesian War. David Aune included a lengthy excursus on Roman prodigies in his commentary on Revelation. Eclipses were among the “unnatural or extraordinary occurrence or phenomenon understood as a sign warning of divine anger” in Roman culture (Revelation, 2:402).
This means a writer living in 500 B.C. or A.D. 90 who wanted to describe strange apocalyptic signs would naturally include eclipses in their list of cosmic signs. But the word in this context has to mean an unpredicted, unnatural darkness rather than a natural and predictable solar eclipse.
Conclusion. If you live in America, enjoy your eclipse. But do not worry about it as a sign from God ushering in his judgment. Honestly, God has plenty of good reasons to smite America and he does not need to warn us with an eclipse.