OpenAI GPT-5.6 launches with Sol, Terra and Luna

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OpenAI has begun a limited preview of GPT-5.6, introducing three AI models: Sol, Terra and Luna. The release matters because it is not only a product upgrade for ChatGPT, Codex and API users; it also shows how frontier AI access is being shaped by safety concerns, pricing pressure and government scrutiny.

Sol is OpenAI’s flagship GPT-5.6 model, aimed at demanding work across coding, cybersecurity, biology and long-horizon agentic tasks. Terra is positioned as a balanced model for everyday work, while Luna is designed as the fastest and most affordable option for high-volume tasks. OpenAI says Terra has “competitive performance to GPT-5.5” while being twice cheaper, and Luna brings stronger capability at the company’s lowest cost.

The most important detail is access. OpenAI said the GPT-5.6 family will first go to a small group of trusted partners after engagement with the US government. “At their request, we are starting with a limited preview,” the company said, adding that broader availability is planned in the coming weeks.

Pricing also makes the launch significant for developers and enterprises. GPT-5.6 Sol costs $5 per 1 million input tokens and $30 per 1 million output tokens; Terra is priced at $2.50 input and $15 output; Luna costs $1 input and $6 output. OpenAI also says cached-input reads continue to receive a 90 percent discount.

For businesses, the takeaway is clear: GPT-5.6 is a capability upgrade, a cost reset and a governance test. The winners will be teams that benchmark Sol, Terra and Luna against real workflows before moving critical systems.