awarehorizon // atlas_record
Mars
A cold desert carved by water that no longer flows.
- classification
- Terrestrial planet
- system
- Inner solar system
Mars is the fourth planet from the Sun and the most thoroughly explored world beyond Earth. Its thin atmosphere cannot sustain liquid water at the surface today, but its landscape records a very different past.
- Mean radius
- 3,389.5 km
- Surface gravity
- 3.72 m/s²
- Orbital period
- 687 Earth days
- Orbital distance
- 227.9 million km from the Sun (mean)
- Surface temperature
- about −63 °C mean; roughly −140 °C to +20 °C range
Only values with an established scientific consensus are listed. Where a quantity is uncertain or model-dependent, it is discussed in the sections below rather than stated as data.
Liquid water once shaped the surface
Valley networks, delta deposits and layered sediments record standing and flowing water early in Martian history.
The atmosphere is thin and mostly carbon dioxide
Surface pressure is under one percent of Earth's, far too low for stable liquid water in the open.
Mars is losing atmosphere to space
The planet has no global magnetic field today, and the solar wind strips ions from the upper atmosphere at a measurable rate.
Orbital imaging
High-resolution orbiters mapped river valleys, deltas and sedimentary layering across the surface.
In-situ rover analysis
Rovers examined rocks directly and found clays and sulphates — minerals that form in the presence of water.
Spacecraft particle measurements
Orbiting instruments measure escaping ions, quantifying atmospheric loss driven by the solar wind.
- Where did the remaining water go — locked in subsurface ice, bound in minerals, or lost to space?
- Did Mars ever host life?No evidence has been found; the question remains genuinely open.
- How long did surface water persist, and was it continuous or episodic?
Items above are unresolved. Hypotheses are labelled as such and are not presented as confirmed findings.