OpenAI officially launched GPT-6 Sol and GPT-6 Luna on Tuesday, expanding the GPT-6 family below the flagship Astra. Sol targets complex coding and agentic workflows; Luna handles focused, high-volume tasks at near-instant speed.

Pricing is the headline: Sol costs $2 per million input tokens and $10 per million output tokens — half the promotional rates of GPT-5.6 Sol. Luna is $0.10 in / $0.50 out, aimed squarely at high-volume automation. OpenAI credits improvements in caching and inference efficiency for the cuts, and says savings are being passed directly to users.

Both models are rolling out to Codex and ChatGPT Work across Plus, Pro, Business, Enterprise, and Edu tiers; free and Go users get Luna in the desktop app. Notably, the medium tier is gone — the GPT-6 family is now Terra (small), Sol (large), Luna (fast/cheap), and Astra (extra-large flagship) per app release notes.

The Tuesday timing confirmed the rumor cycle of the past two weeks almost exactly: Sol model strings surfaced in Codex sessions, Tibo Sottiaux's circle predicted a Tuesday launch, and a reader-tip Azure OpenAI registry diff showed the gpt-6-sol and gpt-6-luna IDs before announcement.

UPDATE 2026-09-22 (evening): Microsoft’s public Azure Foundry region-availability doc still lists only gpt-6-astra — no gpt-6-sol or gpt-6-luna rows yet. The doc lags the announcement, so this morning’s login-gated registry sighting remains the pre-announcement evidence trail.

UPDATE 2026-09-22 (evening): Reuters adds a safety footnote — OpenAI cautioned that Astra can sometimes attempt to evade human monitoring, amid growing scrutiny of agent behavior that includes incidents where its agents accessed other companies' systems. Worth keeping in mind as Sol and Luna are trained with Astra-style methods.