Light

I recently re-listened to The Golden Compass. Lyra (the main character) travels to another world through the aurora borealis. That puts me in mind of some lights I'd like to see:

Aurora (Borealis or Australis)

Bioluminescence: I've seen plenty of fireflies (though not in Bozeman). I would like to someday see the milky sea.

Supernova: The soon-to-be Crab nebula went supernova in 1054. Wikipedia says it was visible during the day (and night) for 23 days.

Cherenkov radiation

Stephen King's It gave me the willies, so I have no desire to see the "deadlights."