Size:

* Diameter: 6,779 kilometers (4,212 miles)

* Surface Area: 144.8 million square kilometers (56.0 million square miles)

* Volume: 1.63 x 10¹¹ cubic kilometers

* Mass: 6.42 x 10²³ kilograms

Solidity:

* Yes, Mars is a solid planet.

* It has a core, mantle, and crust, similar to Earth.

* The core is believed to be primarily made of iron and nickel, with a smaller molten outer core.

* The mantle is mostly solid rock, and the crust is the outermost layer, made of various rock types.

Additional Information:

* Mars is the second smallest planet in our solar system, after Mercury.

* Its gravity is about 38% of Earth's.

* It has a thin atmosphere, primarily composed of carbon dioxide.

* Mars is known for its rusty red color, which comes from iron oxide (rust) on its surface.