天 (tiān): Sky or heaven. In this context, it represents the vast, shared world or the expanse that covers everyone.
各 (gè): Each, every, respectively. It points to the individuals involved being in separate states.
一 (yī): One.
方 (fāng): Direction, side, place. Here, “一方” means “one place” or “one corner/side.”
When combined, 天各一方 literally translates to “sky, each one place.” The imagery created is powerful: under the immense, singular sky (天), we are each (各) in our own separate place (一方). It emphasizes both our connection (under the same sky) and our separation (in different places).
This idiom is more formal and literary than everyday slang. You'll hear it in heartfelt conversations, see it in writing, and find it frequently in song lyrics and movie dialogues.
Describing Old Friendships: It's very common to use this when talking about college or high school friends who have scattered across the country or the world for work after graduation.
Long-Distance Relationships: Couples in a long-distance relationship (异地恋, yìdìliàn) might use this to describe their difficult situation.
Family Separation: It's used to describe siblings who have grown up and moved to different cities, or family members who have emigrated.
The connotation is almost always melancholic and nostalgic. It's not a neutral, factual report of distance; it's an expression of the sadness that this distance causes.