What happens if a Star Explodes near the Earth?

 What happens if a Star Explodes near the Earth?

Well, the nearest star from earth is the Sun. The sun is never going to explode because it has very less mass than required. However, if we increase it's mass by 8 times of its current mass, it will explode to be a neutron star.

What happens when the Sun explodes?

If you held the hydrogen bomb near your eyeball and detonate it, that explosion still be a billion times less bright than the brightness of watching the exploding Sun from earth.

How bright a supernova is?

Supernovas are insanely bright. They appear brighter than hundreds of billions of stars combined. They are so much bright, we can observe them from billions of light year far. 

They are so much bright that they appear out of nowhere in the sky.