Mars

Our outermost neighboring planet is the fourth planet in the solar system and, like the other three inner planets, is a "rocky planet." Because of its striking red color, it was named in ancient times after the Roman god of war, Mars (Greek: Ares), and was associated with war and disasters.

As recently as a century ago, it was even widely believed that Mars might be inhabited by an alien civilization. The red color of Mars’ surface is due to its iron oxide content—in other words, rust.

Because of its relatively close proximity to Earth, the planet has been actively studied with the help of space probes since 1965, and as early as 1976, a Viking probe achieved the first soft landing. Even back then, the focus was on whether traces of life could be found on our neighboring planet.

Mars is the most Earth-like planet in the solar system. A Martian day is about 0.5 hours longer than an Earth day, and a Martian year lasts just under two Earth years. The planet has a very thin atmosphere composed of carbon dioxide, and temperatures range from minus 85°C at night to as high as plus 20°C during the day. The Martian landscapes are also extreme: there are taller mountains (up to 26 km) and deeper canyons than on Earth. It is believed that liquid water existed on Mars long ago, perhaps even oceans. Today, there is virtually no water left on Mars, except for trace amounts in the polar caps, along with frozen carbon dioxide (dry ice). The two irregularly shaped moons, “Phobos” and “Deimos,” each only a few kilometers in size, may be small bodies captured from the “asteroid belt” between Mars and Jupiter by the planet’s gravity.

Data Overview

Surface

A rocky planet with high mountains (up to 26 km), deep canyons, and polar ice caps

Number of moons

2 (Phobos, Deimos)

Mass

0.107 Earth masses

Diameter

6,792 km (scale: 1.5 mm)

Distance from the Sun

At perihelion: 206.59 million km
(model: 45.9 m)
At aphelion: 249.23 million km
(model: 55.4 m)

Turnaround time

686 days, 23 hours, 31 minutes

Distance traveled in 24 hours

At perihelion: 2.289 million km
(Model: 51 cm)
At aphelion: 1.898 million km
(Model: 42 cm)

Rotation Duration

24 hours, 37 minutes, 22 seconds

Rotation Axis Tilt

25.19 degrees

Direction of rotation

clockwise (like a train loop)

Average Energy Irradiance

589 watts/m²

Mean Solar Angular Diameter

0.35 degrees

Temperature

Minimum temperature: -153 °C
Average temperature: -63 °C
Maximum temperature: 20 °C

Atmosphere

95.3% carbon dioxide (CO₂)
2.7% nitrogen (N₂)
1.6% argon (Ar)
0.13% oxygen (O₂)

Weather

Each season lasts twice as long as it does on Earth

First Probe Mission

1965 Mariner 4 Space Probe (U.S.)