- OpenAI is releasing a preview of ChatGPT-5.6 to trusted partners on Thursday
- The new GPT-5.6 comes in three versions: Sol, Terra and Luna
- Initial access is via API only, with a wider rollout to ChatGPT later
GPT-5.6 comes in three different versions, Sol, Terra and Luna, but it won’t be anything like the normal ChatGPT releases we’ve been used to. First, there will be a limited preview for trusted partners, followed by a wider rollout later. The preview begins this Thursday for the lucky ones.
The staggered rollout is not by OpenAI’s design. In a release about the new models, OpenAI said: “As part of our ongoing engagement with the US government, we previewed our plans and the models’ capabilities ahead of today’s launch. At their request, we are starting with a limited preview for a small group of trusted partners whose participation has been shared with the government before releasing more broadly.”
The delay comes after US President Donald Trump signed an executive order establishing a voluntary framework under which AI developers could give the US government access to their new models for up to 30 days before releasing them to trusted partners.
OpenAI is clearly unhappy with the situation: “We don’t think this kind of public access process should become the long-term standard. It keeps the best tools from users, developers, enterprises, cyber defenders and global partners who need them.”
Meet Sol, Terra and Luna
OpenAI is launching GPT-5.6 as a family of three models named after celestial bodies, rather than the more usual naming conventions like “Instant” and “Mini”. Sol, Terra and Luna are three versions of the new ChatGPT-5.6, each aiming for a different balance between intelligence, speed and cost.
GPT-5.6 Sol is the flagship model and OpenAI’s most capable AI to date. This is the model for the toughest tasks: complex coding, multi-step reasoning, agent-style work and specialist tasks where accuracy matters more than speed. OpenAI says that Sol has improved capabilities in coding, biology and cybersecurity, and that it also gets new “max” and “ultra” modes designed to give it more time and, in ultra mode, extra subagents to work through complicated tasks. You can think of Sol as the ‘big-brain’ version of GPT-5.6 that you want when the question is hard enough that it’s worth waiting a little longer.
GPT-5.6 Terra is the middle option and probably the one most regular people will use. OpenAI describes it as a balanced model for everyday work, with performance competitive with GPT-5.5, but at half the price. That makes the Terra sound like the likely daily driver model: powerful enough for writing, planning, research, coding assistance, and general ChatGPT use, but not as expensive or heavy as the Sol. If Sol is the specialist you call on for the tough problems, Terra is the model you expect to use for most normal tasks.
GPT-5.6 Luna is the fast and affordable model. It’s designed to offer strong capabilities at OpenAI’s lowest price in the GPT-5.6 family, suggesting it’s aimed at quick responses, lighter tasks, and high-volume usage where speed matters. This is the model you would expect to handle simpler questions, summaries, paraphrases, quick brainstorming and everyday back and forth without needing the full power of the Sun. Luna might not be the standout model, but it could end up being the one people interact with the most if it makes ChatGPT feel faster and cheaper to run.
What will you notice?
As I’ve mentioned before, the test for new AI models, like GPT-5.6 or Claude Sonnet 5, will increasingly be how well they handle multi-step tasks and agent processes.
For regular ChatGPT users, the most obvious change using GPT-5.6 may not be a dramatic new button or interface. It’s likely that ChatGPT will feel more capable when you ask it to do something complicated and less like a chatbot that needs to be painstakingly walked through each step.
This matters because most people don’t use ChatGPT by comparing benchmark scores. They sense if it understands a messy request, remembers the point of the task, follows instructions properly, and gets closer to a finished result the first time. If GPT-5.6 works as OpenAI suggests, the upgrade should be most noticeable in the moments when today’s models still feel impressive but a little fragile.
When can I get it?
OpenAI’s three-model structure is interesting, and it’s not clear if the ChatGPT version automatically sends your request to different models depending on how complex it is. Obviously, not all tasks need the same level of intelligence. A fast, cheaper model like Luna could handle simple summaries, paraphrases and everyday questions, while a more powerful model like Sol could be reserved for tougher work where depth matters more than speed.
GPT-5.6 is not available in ChatGPT during the preview, so regular users may not notice any of this right away. OpenAI says the models are currently available via API and Codex to a limited group of trusted partners and organizations, with wider availability through ChatGPT planned later.
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