On May 22, 2016, Mars and the sun will be positioned on opposite sides of the Earth in what is known as a "Mars opposition." This line-up occurs roughly every 26 months. Eight days after the Mars opposition, on May 30, 2016, a Mars "close approach" occurs. A close approach is the point in Mars' orbit when the Red Planet comes the closest to Earth. At its closest approach, Mars will be 46.8 million miles away (75.3 million kilometers). If Mars and Earth had perfectly circular orbits, close approach would occur at the same time as opposition. However, since Mars and Earth both have elliptical orbits, the close approach is not aligned with opposition, and varies from year to year.