A few cool things:
Here are some of the most amazing things I have ever seen (so far, so t"once in a lifetime", unfortunately):
The total solar eclipse on August 21, 2017 in Culver, Oregon -- the coolest, and weirdly emotional, most amazing 2 minutes of my recent life. Everyone told me not to waste time to try to take pictures. They were right. The only halfway decent ones I got were from time lapse I had running on the side. There was a guy there who had traveled from Manchester, who had been to one before. When we asked him if it was worth the trouble to come all the way to Central Oregon, he said he would have swam and walked if he would have had to. He too was right.
I once (and only once) saw a meteor storm - I think it may have been the Leonids of 2002. I was at a wedding in Carmel when it started, and you could see a rain of shooting stars for hours - like several, sometimes dozens, at the same time and going on continuously, brightly visible, even with all the lights on in the back yard and while driving on the freeway. I stayed up all night.
We saw the Space Shuttle in orbit, when it was about to dock with the International Space Station. It was dusk (just after sunset), we were going for a brief walk in Napa, and there they were - lit up by the setting sun, brighter than anything else in the sky, passing by at satellite speed close behind one another in the same direction. I saw the shuttle in flight two other times - both times on the back of a NASA 747. The first time was at the Paris Air Show in 1983, and the last time was on its farewell tour, when it did a fly-by at Moffett Field in 2012.
Weirdly, all these have to do with things in space. Yeah no I'm not an astro guy, but I do think the Smithsonian Air and Space Museum (and its unfortunately incomprehensibly named cousin at Dulles) is very, very cool. I also spend way too much time at night gazing at the stars, trying to internalize, in a Rubik's cubian sort of way, the well understood models of how earth, sun, moon, planets, and various constellations all move relative to one another and how that translates into what I'm seeing from my position at this time.
The corollary: those natural phenomena which sound cool but end up being underwhelming when you actually see them:
Partial eclipse (sun, moon - ok, it's mildly interesting and kind of cool, but nothing more)
Almost any hyped meteor shower -- where you get all excited and then go out late at night and wait, and after half an hour maybe see a shooting star or two (and freeze your butt off). Well, ok, shooting stars are always cool but still.
Halley's comet (1986). Wtf? That was supposed to be a once-in-a-lifetime thing -- that little schmear? I'll take the comet Hyakutake (1996) or Hale-Bopp (1997) any time - now those were cool. They probably deserve to be on the list above, except you could see them for a long time.