Mars and Earth orbit the sun at different speeds: Earth has an inside track and gets around the sun more quickly. Plus, both have elliptical orbits, rather than perfect circles. So the distance to Mars from Earth is constantly changing. In theory, the closest the planets could come together would be when Mars is at its closest point to the sun (perihelion) and Earth is at itsfarthest point (aphelion). In that situation, the planets would be 33.9 million miles (54.6 million kilometers) from each other. But that has never happened in recorded history. The closest known approach was 34.8 million miles (56 million km) in 2003 ....... :D!
