Yes, there is! The planet "B" is a popular designation for exoplanets, which are planets outside of our solar system.

Here's how it works:

* Star Names: Astronomers often use letters to identify planets orbiting a specific star. For example, the star Proxima Centauri has a planet called "Proxima Centauri b."

* Discovery Order: The letter "b" is given to the first planet discovered orbiting that star. Subsequent discoveries get letters like "c", "d", and so on.

So, while there's no planet in our solar system that starts with "b", there are many exoplanets that do!