Terrestrial planet
Mars
The red planet
Mars is the fourth planet from the Sun, a cold desert world famous for its rust-red color, which comes from iron oxide in its soil. Mars has the largest volcano in the solar system, Olympus Mons, and a canyon system, Valles Marineris, that would stretch across the United States. Ancient riverbeds and minerals that form in water show Mars was once warmer and wetter, making it the prime target in the search for signs of past life.
Quick facts
- Distance from Sun
- 228 million km (1.52 AU)
- Diameter
- 6,779 km (0.53x Earth)
- Day length
- 24.6 hours
- Year length
- 687 Earth days
- Moons
- 2 (Phobos and Deimos)
- Avg. temperature
- -63 C
What's it like there?
A day on Mars feels familiar at 24.6 hours, and Mars has seasons like Earth thanks to a similar axial tilt. But the air is thin carbon dioxide, only about 1% of Earth's pressure, and average temperatures sit around -63 C. Dust storms sometimes grow to engulf the entire planet. The sky is butterscotch-colored by day and sunsets appear blue. Water exists today as polar ice caps and subsurface ice.
Notable moons
Phobos
Larger moon, orbiting so close it circles Mars three times a day; slowly spiraling inward.
Deimos
Smaller, outer moon, about 12 km across.
Fun facts
Olympus Mons is about 2.5 times the height of Mount Everest.
Mars sunsets appear blue because of how fine dust scatters light.
Pieces of Mars have landed on Earth as meteorites.
Mars' polar ice caps are made of water ice and frozen carbon dioxide.
A Mars year lasts almost two Earth years, so each season is about twice as long.
Exploration history
Viking 1 & 2 1976
First successful Mars landers, returning surface photos and soil tests.
Curiosity 2012+
Rover that confirmed ancient Mars had conditions suitable for life.
Perseverance & Ingenuity 2021+
Rover caching samples for return; Ingenuity made the first powered flight on another planet.
Mars vs Earth
| Property | Earth | Mars |
|---|---|---|
| Diameter | 12,742 km | 6,779 km |
| Year length | 365 days | 687 days |
| Moons | 1 | 2 |
| Average temperature | 15 C | -63 C |
| Gravity | 1 g | 0.38 g |
Scientific Sources & Provenance
All data is verified against official space agency records (NASA, ESA, and IAU).
- NASA Science / Mission Datahttps://science.nasa.gov/mars/
- NASA Science / Mission Datahttps://mars.nasa.gov/
- NASA Science / Mission Datahttps://nssdc.gsfc.nasa.gov/planetary/factsheet/marsfact.html