Some of these I have been thinking on for a while and as such are additions to the planet event idea.

New years party: +10% population, +5% artifact production. (The planet has gained a new year on its cycle and is have a massive party.)

Magnus Visit: +15% defense. (Some caption that is taking the Journey of the Magnus mission has come to this planet [higher chance to happen when doing the mission]).

shouldnt the magnus visit be after the mission is completed instead of during the mission? otherwise people will just do one click and then stop. but i love both ideas. specifically the new years party. every drop of artifact helps.

Exactly.