Do you know what would happen if a single star fell to the earth? The very notion is absurd. Most stars (like our sun) are millions of times larger - and thus more massive - than the earth. So a star wouldn't "fall" to earth in the first place. The earth would have to "fall" into a star, and the effect would be something like a huge whale swallowing up a microscopic plankton. I doubt that our planet would even make much of a ripple across the surface of an enormous star. And, of course, it would then be instantly destroyed by heat. If that is the case, though, then why do popular passages in the Bible like Revelation 6:13 talk about all of the stars falling to earth as if they are only as big as they appear to us in the night sky? Clearly, if a verse like Revelation 6:13 is not meant to be the absolute end of human history (and there's quite a bit more in Revelation after chapter 6), then what we have in verse 13 is a figurative statement.
In fact, we find this same picture of judgment on heavenly lights repeated over and over again throughout the Scriptures. Just take a look at passages like Isaiah 13:10, 24:21-23, Ezekiel 32:7, Joel 2:10, Amos 8:9, and Micah 3:6. In other words, God has promised this kind of judgment before on nations like Egypt, Babylon, Assyria, and Tyre. When we get to Matthew 24:29 and Revelation 6:12-13, the judgment is being directed at apostate Israel, but just as in previous times and previous judgments, what is being described concerning the sun, moon, and stars is not a permanent destruction of celestial bodies, but rather a removal of authority, influence, power, and leadership.
Heavenly lights often represent ruling authority like that of nations or individual rulers, and therefore the failing of those lights represents the collapse of that leadership (see for example Isaiah 14:12-15). So in a passage like Revelation 6 (or Matthew 24), the lights are failing in the judgment of Jerusalem, which points to the removal of its power and authority.
But we find the opposite of this failing light effect in Isaiah 30:26, when the prophet, speaking of the renewal of the people in Zion (New Covenant) says, "Moreover, the light of the moon will be as the light of the sun, and the light of the sun will be sevenfold, as the light of seven days, in the day when the LORD binds up the brokenness of His people, and heals the wounds inflicted by His blow."
Now if that verse is meant to be taken literally, then something that is clearly supposed to be a good thing: the brightening of sun and moon versus the darkening of them as seen in so many judgment oracles, would become a horror. Even now we stress over the amount of sunlight that touches our skin. Imagine if it was seven times stronger! It would burn every living thing on the earth to a crisp! And a moon shining like the sun? Is that good? I suppose a better question is: has this happened? We understand from reading Isaiah 30 that this is a New Covenant blessing, so we should be living in the time of super-sun and sunny-moon even now.
It ought to be apparent that what is being referred to in Isaiah 30 is the reverse of what was being referred to in all of the failing light oracles. As the other passages indicated a collapse of authority and rule, this intensifying of the light represents an increase in the authority and rule of the New Covenant people of God. In other words, what would start as a tiny mustard seed in Jerusalem on the day of Pentecost would grow and intensify until it spread around the globe. As the church of the Lord Jesus Christ grows and conquers by the power of the gospel, its influence in the world will brighten.
This is a fantastic message of hope for Christians. This world is not something to fear and withdraw from - waiting for the day when Jesus will come back to rescue you. It is a Promised Land to conquer in the name of Jesus Christ with the sword of the Spirit (which is the Word of God) and in the power of the Holy Spirit by the grace of God. So get out there and shine like the stars in the heavens (Philippians 2:15)!