GPT-5.6 Explained: How Luna, Terra, and Sol Differ

OpenAI's new GPT-5.6 family splits into three named tiers — Luna, Terra, and Sol — under a "scales with your ambition" pitch. Here's what changed, how the tiers are organized, and how it reaches Microsoft 365 Copilot.

07/10/2026 · Model Evaluation · 6 min read