That statement is incorrect. Jupiter is indeed the largest planet in our solar system, but it's not twice as big as all the other planets combined.

Here's why:

* Volume vs. Mass: It's important to distinguish between size and mass. While Jupiter is the largest in terms of volume (the amount of space it takes up), it's not the most massive.

* Combined Mass: The combined mass of all the other planets in our solar system is actually greater than the mass of Jupiter.

Therefore, the statement that Jupiter is twice as big as all the other planets combined is not true.