Surface area

Surface of Mars imaged by the Hubble telescope as a composite of four images between April 27 and May 6, 1999.

The surface area of any object is the total measure of the area of its surface. For an object in a hydrostatic-equilibrium or near-spherical shape, the surface area is a function of the equatorial and polar radii of the object. But some objects, like the Martian moons Phobos and Deimos, have highly irregular shapes, and their surface areas do not lend themselves to an accurate calculation.

Surface areas of solar system bodies are often given not only in traditional units of area but also as a fraction or multiple of the surface area of the earth.