The snap best friends planets feature is part of Snapchat+, where planets represent your position on another person's Best Friends list.
Mercury represents the closest ranking, while the other planets follow in order until Neptune.
These positions can change over time depending on how your interactions with different friends develop.
It’s a fun way to explore Snapchat’s social features, but the ranking doesn’t necessarily reflect the full strength of a real-life friendship.
Have you noticed your planet position changing even when your friendship seems just as strong?