Two of Saturn’s moons. Dione is the nearer one, and Enceladus is the snowball in the back. They are made of the same material, but obviously Enceladus has much higher reflectivity.
Enceladus has a 314 mile diameter. That means it would just about fit between Phoenix and San Diego.
Dione in the foreground has a diameter of 698 miles, more than twice that of Enceladus. It’s the 15th largest moon in the solar system.
It is boundlessly fascinating to me that we live in an age where we can see the moons of a far-away planet in this detail.