After how many years of formation of Earth did life appear?

The appearance of life on Earth is estimated to have occurred around 3.5 to 3.8 billion years ago, which would be roughly 500 million years after the Earth's formation, estimated to have occurred about 4.5 billion years ago. This timeline aligns well with fossil evidence of the earliest stromatolites, which are structures created by microbial communities.

The significance of this answer lies in understanding that while Earth underwent significant geological and atmospheric changes in its early years, the emergence of life required a stable environment with liquid water, suitable temperatures, and complex chemistry. Therefore, the answer indicating 500 million years highlights a crucial transition in Earth's history, marking the dawn of biological processes that would eventually lead to the diverse life forms we see today.

Other timeframes, like 100 million, 300 million, or even 1 billion years, represent periods well before or after the actual emergence of life, making them less accurate in the context of when life first appeared on our planet.