you asked the right person that question ha ha.
A major event that takes place which the entire planet would see at the same time.
One that I can think of is a MASSIVE solar flare or micro nova of our sun. Night would change color it would be so massive.
Some of the smaller dwarf Galaxies only have about a billion stars. The spoke in the milky way we're on on is part of a Dwarf Galaxy that merged. The next merger is with the Sagittarius galaxy. Which the core is passing through the milky way right now.
Sagittarius galaxy has a very long dust trail that is heading toward Sol. I'm not sure when the dust will arrive though it should be in the within 100 years and it lot of dust.
This is a representation of the Sagittarius galaxy passing through the Milky way. What they call the "leading tidal debris" I read is much closer then what it shows in this pic.
The dust and debris in my opinion could easily trigger a micro solar flare