In my case it’s clear blue skies and anything like stillness or being relaxed.
Edit: for some context the footage of 9/11, the people falling off the plane in Afghanistan, the explosion in Beirut, and many others had that same ominous clear blue sky in the background.
Black holes fill me with a sense of doom.
For most intents and purposes, they’re no more dangerous than a star of the same mass in the same place.
There’s also the theory that our universe could be the inside of a black hole in a higher-order universe.
Of course, trying to imagine the size of our universe, let alone an entire hierarchy of them where ours may just be itself an insignificant speck, might cause more doom sensation than less. Do with this information what you will.
I think it’s the time dilation and spaghetti. And they can be damn difficult to spot. Or it may just be pure irrationality.