Most such points of reference have been personal, principally times I have moved to a new place for a new university or job. The only real external event that has shaped my life was covid, and I refer to before 2020 as "before times". It coincided with a big change in life circumstances as well as the general disruption.
Quite a few people now have "pre-covid" as one of their reference points.
New Horizons probe mission has been "big" connector of life for me - I was still in high school when it launched (2006) and I was 3 (!!!) dropsfrom University and 1 "finished" trade (log builder stuff) school later when first detailed images of Pluto arrived (2015).
Life after that has been much more clear as last "reachable" big mystery was solved - Pluto might not be planet but it has BIG heart![]()
I'd say the eventual trip to Mars and finding out if there's life on any of Jupiter and Saturn's moons are pretty big reachable mysteries.