Like the rest of the planets in the Solar System, Mars travels an elliptical orbit around the Sun. This means that it has a closest point to the Sun in its orbit as well as a distant point.
When an object reaches the closest point in its orbit, astronomers call this “perihelion”. The perihelion for Mars is 207 million km, or 1.38 astronomical units (1 AU is the average distance from the Earth to the Sun).
The most distant point on an orbit is called aphelion. The aphelion for Mars is 249 million km, or 1.67 AU.
The average distance from Mars to the Sun is 228 million km, or 1.52 AU. Astronomers call this the semi-major axis.
Mars actually has the second most eccentric orbit of all the planets in the Solar System, right after crazy Mercury. The wide ranging distances have a significant impact on its seasons. When Mars is at perihelion, its southern hemisphere is tilted towards the Sun, and can heat up much more than when its northern hemisphere is experiencing summer.
The dust storms that can rage across the entire planet usually get going when the distance from Mars to Sun is the smallest.
Finally, if you’d like to learn more about Mars in general, we have done several podcast episodes about the Red Planet at Astronomy Cast. Episode 52: Mars, and Episode 91: The Search for Water on Mars.