On June 27, 2026, Beijing Time, OpenAI officially rolled out the GPT-5.6 series models, which include three variants: Sol, Terra, and Luna, named after the Sun, Earth, and Moon, respectively. Sol, the flagship model, is tailored for complex reasoning and challenging tasks. It boasts a new "Full Power" setting and an "Extreme" mode, enabling it to harness sub-agents for managing intricate workflows. This model shines in fields such as cybersecurity and biological research. Terra, on the other hand, is a well-balanced model that delivers performance comparable to GPT-5.5 but at roughly 50% lower costs. It is ideally suited for enterprise applications and daily productivity tasks. Luna, the most economical model in the GPT-5.6 lineup, prioritizes speed and affordability, making it perfect for large-scale online services and high-throughput scenarios. Currently, the GPT-5.6 series is in a limited preview phase, accessible only to a select group of trusted partners. OpenAI plans to gradually extend access to a wider audience in the coming weeks.