[pjc50]

From Newtonian mechanics, the orbit can only change by applying a force from somewhere, and a big move would require a lot of energy. And there's no evidence of such an event in the geologic pas; if it was triggered by an impact, it would be far larger than the one which killed the dinosaurs.

[wool_gather]

There's a reasonably thorough discussion of this topic, from an...interesting...perspective, in this essay: "How to Destroy the Earth" https://qntm.org/destroy

[dr_zoidberg]

Addendum: far larger than the one that created the moon.