Terra is likely dead and that is probably a good thing. It was only slightly better than Luna but significantly more expensive. This is a great lineup. Right now, Luna > Haiku, Opus > Sol, and Astra > Fable.
Please welcome GPT-6 Sol and GPT-6 Luna to the GPT-6 universe.
GPT-6 Sol and Luna build on the advances behind GPT-6 Astra, bringing much of its strengths into faster and more affordable models to support work at scale.
We’ve also made caching and inference more efficient, and we’re passing the savings directly to you: 50% lower API prices for Sol and Luna compared with GPT‑5.6 promotional pricing.