Mars Journey

Mars follows an elliptical orbit around the Sun at an average distance of 142 million miles (228 million kilometers). It completes one full orbit every 687 Earth days, giving the Red Planet a year nearly twice as long as Earth’s. Mars travels at an average orbital speed of about 54,000 miles per hour (87,000 km/h).

The orbit of Mars has a noticeably higher eccentricity than Earth’s, causing greater variation in its distance from the Sun. At perihelion (closest approach), Mars is about 128 million miles from the Sun. At aphelion (farthest point), it reaches 154 million miles. This variation contributes to more extreme seasonal changes than those on Earth.

Seasonal Effects and Orbital Tilt

Mars has an axial tilt of approximately 25 degrees, very similar to Earth’s 23.5 degrees. Combined with its elliptical orbit, this tilt produces distinct seasons that last roughly twice as long as Earth’s. When Mars is closest to the Sun during its southern summer, the increased solar heating can trigger planet-wide dust storms that last for weeks or months.

The changing distance also affects the apparent brightness of Mars from Earth. Every 26 months, when Earth overtakes Mars in its faster inner orbit, the two planets come relatively close, creating favorable windows for spacecraft launches.

Orbital Characteristics

Mars takes 687 Earth days to complete one orbit, during which it moves through the zodiac constellations at a slower pace than inner planets. Its orbital path lies entirely outside Earth’s, so Mars never shows phases like Venus or Mercury when viewed from Earth. Instead, its appearance changes mainly in brightness and size as the distance between the two planets varies.

Two small moons, Phobos and Deimos, orbit Mars in nearly circular paths. Phobos, the inner moon, orbits so quickly that it rises in the west and sets in the east, completing three orbits per Martian day.

Human Exploration and Mission Planning

Mars’s orbit plays a critical role in mission planning. Launch windows to Mars occur approximately every 26 months when the planets are properly aligned for efficient transfer orbits. Most spacecraft use a Hohmann transfer trajectory — a large elliptical path that takes about 7 to 9 months to reach Mars.

Once at Mars, orbiters must carefully slow down to be captured into orbit around the planet. Many missions use aerobraking, dipping into the thin Martian atmosphere to gradually lower their orbit and save fuel.

Scientific Value of Mars’s Path

Studying Mars’s orbit helps scientists understand the long-term climate history of the planet. Evidence suggests that Mars once had a more circular orbit and different axial tilt, which may have supported liquid water on its surface billions of years ago. Today, its elliptical path contributes to the harsh, cold conditions that dominate the planet.

Ongoing and future missions continue to use Mars’s predictable orbital path to conduct detailed studies of its geology, atmosphere, and potential for past or present life. The Red Planet’s journey around the Sun remains one of the most important targets for understanding how planetary orbits influence habitability.

Sources & further reading: NASA – Mars • NASA Solar System Exploration – Mars