NKJV Luke 21:10-11
Then He said to them, “Nation will rise against nation, and kingdom against kingdom. And there will be great earthquakes in various places, and famines and pestilences; and there will be fearful sights and great signs from heaven.

NLT
… and there will be terrifying things and great miraculous signs in the heavens.

NIV
…and fearful events and great signs from heaven.

NAS
…and there will be terrors and great signs from heaven.

While reading and studying this morning, I had to stop on the above scripture.
You can read the entire discourse if you wish but I wonder about the phrase “fearful sights”.
It is the Greek word phobetron, which contains a root of our word phobia.
It seems to be linked together with the great signs in the heavens so I tend to conclude that it is a fearful sight from the heavens.
The Revelation mentions a great star fell from heaven, burning like a torch, and it fell on a third of the rivers and on the springs of water. Rev 8:10-11
That sounds pretty well like an asteroid or comet hitting the earth.
At 7:17 AM on the morning of June 30, 1908, a mysterious explosion occurred in the skies over Siberia.
It was caused by the impact and breakup of a large meteorite, at an altitude roughly 4 miles in the atmosphere.
You can get a sense of the magnitude of this event by comparing observations made at different distances.
Seismic vibrations were recorded by sensitive instruments as much as 600 miles away.
At 300 miles, observers reported “deafening bangs” and a fiery cloud on the horizon.
About 110 miles from the explosion, the object was seen in the cloudless, daytime sky as a brilliant, sun-like fireball; thunderous noises were heard.
At distances around 40 miles, people were thrown to the ground or even knocked unconscious; windows were broken and crockery knocked off shelves.
Probably the closest observers were some reindeer herders asleep in their tents in several camps about 20 miles from the site.
They were blown into the air and knocked unconscious; one man was blown into a tree and later died. “Everything around was shrouded in smoke and fog from the burning fallen trees.”
Could this happen again?
Yes, I believe Revelation is evidence that it positively will!