OpenAI opens GPT-5.6 Sol, Terra and Luna to the public

OpenAI began rolling out its GPT-5.6 model series - Sol, Terra and Luna - to all users on July 9, after an initial late-June preview that had been limited to government-approved partners pending a federal safety review. Sol is the flagship tier tuned for demanding domains such as biology, chemistry and cybersecurity, Terra is a balanced mid-tier, and Luna is the fastest and most affordable option. Preview API pricing runs $5/$30 per million input/output tokens for Sol, $2.50/$15 for Terra and $1/$6 for Luna.