It’s not a great picture of Jupiter, but that’s not the point. The point is that this photograph was taken by NASA’s Cassini spacecraft currently orbiting Saturn. When the picture was taken, Cassini was approximately 1.8 billion kilometres from Jupiter. So, at the time of the photograph, the distance from Saturn to Jupiter was roughly the same as the distance from the Earth to Saturn. A similar picture of Earth would only light up a single pixel in Cassini’s camera.

https://solarsystem.nasa.gov/resources/13540/hello-again-jupiter/