Also a thing to consider. Old temples and ancient legends have some things in common. Sky and Serpents.
>They aim at a specific point in the sky>They often involve serpentsAnd not just any kind but often feathered and related to the sky often described as trying to swallow the sun. In China we have their version of a dragon that looks coiled with mustache looking things often related to thunder and a ball of lightning at his feet, in South America you have their winged serpent god Quetzalcoatl. You have them all over the place they were significant in the old world. Why?
But how can I say for sure it was a nova and not just a simple asteroid strike? Well all the things I mentioned cannot be explained by a simple meteor or a shower. Only an electrical event would do this. And the only thing strong enough to produce it is our Sun.
OK, but what does a micronova do? how are we in danger, specifically?
So basically as the Sun gears up towards the Micronova it begins creating larger CMEs that are so powerful they will take out the electric grid worldwide.
That happens possibly over a decade before the Main event hits (actual Micronova, POSSIBLE Crust Displacement ,coastal megafloods).
Worst case scenario? (that I personally don't believe will happen)
By blasting one side of the earth and evaporating a thousand feet of sea water instantly, which later comes down as rain, and also causing a pressure wave, which causes massive ocean waves. Then all that water freezes and causes what you mite call instant Ice Age.
https://www.youtube.com/watch?v=8DxnCdqt3mw&t=200s 
