World 04 · terrestrial planet
Mars
A cold desert with the memory of water.
Mars is a cold, rocky desert whose surface preserves extensive evidence of a wetter and warmer past.
Editorial representation. Color and relief are interpretive; measurements below use the sourced reference catalog.
- Order from Sun
- 4
- World type
- Terrestrial
Mean radius
3,389.5km
About half Earth’s diameter
Solar day
24h 40m
Only about forty minutes beyond Earth
Mean surface reference
-65°C
A planetary mean, not local weather
Planet portrait
Familiar rhythms, alien conditions
Mars is close enough to invite comparison and different enough to expose where intuition fails.
A day close enough to feel familiar
A Martian solar day is only about forty minutes longer than a day on Earth. That near-match makes the daily rhythm feel intuitive, even while the planet’s year stretches across almost 687 Earth days.
The similarity is useful for human-scale comparison, but it does not make the environment Earth-like: temperature, pressure and breathable air remain entirely different constraints.
Thin air changes every familiar rule
Mars has a thin atmosphere dominated by carbon dioxide. It offers little thermal insulation and no breathable air, so the average surface temperature and pressure cannot be read as ordinary weather conditions.
Helios treats the temperature shown here as a planetary reference value, not a forecast and not a measurement for every location or season.
A dry world that still carries water’s evidence
Channels, deltas, minerals and layered terrain preserve evidence that liquid water once shaped parts of Mars. The planet is presented as a geological record, not as a promise that its present surface is wet or habitable.
Its red appearance comes from iron-bearing minerals in the soil and dust. The visual treatment on this page is editorial, while the physical values remain tied to the cited references.
Personal comparison
Put the numbers against your own body
Gravity, day length and sunlight delay become more understandable when they are related to an Earth reference.
Your Earth reference
What would the scale read on Mars?
Enter an Earth scale reading. The calculation applies the ratio between Mars surface gravity and standard Earth gravity; your mass does not change.
Use a value from 0 to 1,000 kilograms.
Mars scale equivalent
—kg
This is an Earth-style scale equivalent. It is not a medical or body-mass calculation.
Reference signals
Three numbers that change the whole experience
A thin atmosphere dominated by carbon dioxide.
Gravity
Your mass stays; the scale reading changes
Mars surface gravity is about 37.8% of the Earth reference used by Helios. The result is a scale-reading comparison, not a change in mass.
Year
One orbit, hundreds of local days
A Martian year lasts about 687 Earth days, or roughly 668.6 Martian solar days using the reference day length.
Moons
Two small companions
Mars has 2 recognized moons—Phobos and Deimos. The catalog snapshot is dated 2026-07-17.
Exploration record
How we learned to read this planet
Mission summaries are tied to dated official records and are not presented as live telemetry.
- 01
Mars rover mission
Mars 2020 · Perseverance
Perseverance explores Jezero Crater for evidence of past habitability, seeks signs of ancient microbial life and collects rock and regolith samples for possible future return.
Historical field record
Nearest archived observation to September 21
InSight recorded this sol at one landing site. The date below is historical—not “Mars today” and not a planet-wide forecast.
- Sol
- 675
- Temperature °C
- -96.9 / -62.3 / -15.9
min / average / max - Pressure Pa
- 722.1 / 750.6 / 768.8
- Horizontal wind m/s
- 1.1 / 7.2 / 22.5
- Common direction
- WNW
- Samples
- 88,628
to · northern late autumn · southern late spring
Surface context
Three places, three ways to read relief
Mars Trek products are imagery and terrain layers. They do not provide the planet’s orbital position.
Jezero Crater
18.38°, 77.58°
MRO Context Camera mosaic
Mars_MRO_CTX_Clonode_32bit_globalregional mosaic; scale varies by zoom · mosaicOpen Mars Trek Olympus Mons
18.65°, 226.20°
MOLA shaded relief
Mars_MOLA_128ppd_shade128 pixels per degree · hillshadeOpen Mars Trek Valles Marineris
-14.00°, 301.00°
MOLA shaded relief
Mars_MOLA_128ppd_shade128 pixels per degree · hillshadeOpen Mars Trek Mission media
The archive remembers where each image came from
Mars 2020 Perseverance Landing Coverage with Commentary
The largest, most advanced rover NASA has sent to another world touched down on Mars Thursday, after a 203-day journey traversing 293 million miles (472 million kilometers).…
HQNASA media details
How Perseverance Drives on Mars
NASA’s Perseverance Mars rover is using its self-driving capabilities as it treks across Jezero Crater seeking signs of ancient life and gathering rock and soil samples for…
JPLNASA media details
Perseverance Arrives at Mars: Feb. 18, 2021
After nearly 300 million miles (470 million km), NASA’s Perseverance rover completes its journey to Mars on Feb. 18, 2021. But, to reach the surface of the Red Planet, it has to…
JPLNASA media details
NASA’S Perseverance Rover’s First 360 View of Mars
This video shows the first 360-degree view of the landing site of NASA’s Perseverance rover on Mars, as captured by the rover’s color Navigation Cameras, or Navcams. The Navcams…
JPLNASA media detailsScientific limits
What these values do—and do not—describe
Every displayed value keeps its source, definition and date context. Reference values are not presented as observations happening now.
Sources and provenance
- NASA Jet Propulsion LaboratoryPlanetary Physical Parameters ReferenceAccessed Jul 17, 2026
- NASA Jet Propulsion LaboratoryApproximate Positions of the Planets ReferenceAccessed Jul 17, 2026
- NASA SciencePlanet Sizes and Locations in Our Solar System ReferenceAccessed Jul 17, 2026
- NASA ScienceTemperatures Across Our Solar System ReferenceAccessed Jul 17, 2026
- NASA ScienceMars: Facts ReferenceAccessed Jul 17, 2026
- NASA ScienceMars Moons: Facts ReferenceAccessed Jul 17, 2026
- NASA ScienceMars 2020: Perseverance Rover Latest availableAccessed Jul 18, 2026