Drag the time slider to watch Mars's global magnetic field disappear and its atmosphere thin out - real MAVEN mission figures on how fast the solar wind strips gas away, then and now.
Drag to orbit and scroll or pinch to zoom on the scene above. The slider runs from Mars's early history to today; the CME button shows how much faster the real escape rate climbs during a solar storm.
Atmosphere Escape: Mars 3D Explorer
This browser explorer shows why Mars lost most of its atmosphere: a global magnetic field that once deflected the solar wind shut off roughly 3.7 to 4.2 billion years ago, and NASA's MAVEN mission has since measured the atmosphere still escaping today at about 100 grams per second.
Drag the time slider and Mars's translucent atmosphere shell thins out while a faint blue shield arc - a simplified stand-in for the planet's old global magnetic field, not a field-line reconstruction - fades away once the slider crosses the dynamo-shutdown point. Two escape processes run at the same time: a slow, pale drift of gas leaving in every direction (thermal, or "Jeans," escape, which happens with or without a magnetic field) and a faster, directional stream of cyan and violet points pulled away from the sun-facing side (solar-wind stripping, which only turns on once the shield is gone). NASA's MAVEN mission found that today, about 75% of the ions solar wind strips away leave through a tail region behind Mars and about 25% leave through a plume above the poles, with a small remaining share coming from an extended gas cloud around the planet - the cyan and violet streams in this scene represent that same tail/polar split.
- Time slider (0 to 100) scrubs from about 4.5 billion years ago to today; the atmosphere shell and the shield arc respond live
- "Trigger a solar-storm (CME) event" button boosts the solar-wind stripping streams to illustrate the real 10-to-20-times rate increase MAVEN measured during solar storms
- Facts panel states the current era, the field status, the escape rate, and (at today's setting) the real tail/polar ion split
- Slow, pale thermal-escape points drift outward in every direction regardless of the slider position - real Jeans escape does not depend on the magnetic field
- Drag to orbit, scroll or pinch to zoom
- Runs fully in the browser with the vendored three.js engine - no account, no upload
| Figure | Value | Source |
|---|---|---|
| Present-day atmosphere loss rate | about 100 g/s | NASA MAVEN mission (Nov 2015) |
| Escape-rate increase during a solar storm (CME) | 10 to 20 times higher | NASA MAVEN mission (Nov 2015) |
| Tail-region share of today's escaping ions | about 75% | NASA MAVEN mission (Nov 2015) |
| Polar-plume share of today's escaping ions | about 25% | NASA MAVEN mission (Nov 2015) |
| Historical rate needed (wet Mars to today) | 100 to 1,000 times today's rate | NASA MAVEN mission (Nov 2015) |
| Global magnetic field (dynamo) shutdown | roughly 3.7 to 4.2 billion years ago | NASA MAVEN mission (Nov 2015) |
| Mars surface pressure today | about 0.6% of Earth's sea-level pressure | Standard planetary comparison figure |
Students studying planetary science or astrobiology, and anyone curious why Mars ended up dry while Earth kept its oceans, can use the time slider to connect one cause (the lost magnetic field) to one effect (the escaping atmosphere) without reading a research paper first. For the shield that Mars no longer has, see the Earth Magnetosphere 3D Explorer, which renders Earth's active dipole field directly. For a snapshot of Mars's present-day atmosphere structure by altitude rather than its loss over time, see the Planet Atmosphere Scale Heights 3D Explorer. For Mars's surface relief instead of its atmosphere, see the Mars Terrain 3D Explorer.
Everything renders on your device with WebGL. The 3D engine loads once (about 0.7 MB) and is cached.
This is an educational approximation, not a physics simulation. The scene does not solve particle-transport or magnetohydrodynamics physics; the shield arc is a simplified schematic indicator of when Mars had a global field, not a field-line model; the ancient atmosphere thickness shown while scrubbing back in time is illustrative, since MAVEN's 100 g/s rate and 75/25 ion split are present-day measurements only, and the "100 to 1,000 times higher" figure describes the average historical rate needed rather than a measured curve through time.
Frequently Asked Questions
Why did Mars lose most of its atmosphere?
Mars's global magnetic field (dynamo) shut off roughly 3.7 to 4.2 billion years ago. Without that shield, the solar wind has been directly stripping the atmosphere away ever since - NASA's MAVEN mission measures the present-day loss rate at about 100 grams per second.
How fast is Mars losing its atmosphere today?
About 100 grams per second, according to NASA's MAVEN mission - roughly a quarter pound per second. That rate climbs 10 to 20 times higher during solar storms (CMEs).
Where does the escaping gas actually go?
MAVEN found three regions: about 75% of escaping ions leave through a tail region behind Mars, about 25% leave through a plume above the poles, and a small remaining share comes from an extended gas cloud around the planet.
Was Mars's escape rate always this slow?
No - to go from a wetter, thicker-atmosphere world to today's thin one, the average historical rate needed to be 100 to 1,000 times higher than today's measured rate. This scene does not have a measured rate curve for that ancient era, only today's MAVEN figure and the historical range needed overall.
What is thermal (Jeans) escape, and is it different from solar-wind stripping?
Yes. Thermal escape happens when the fastest-moving gas molecules in the upper atmosphere simply drift away in every direction - it happens with or without a magnetic field. Solar-wind stripping is a directional process driven by the solar wind, and it is what turned on once Mars lost its magnetic shield.
Does Earth lose its atmosphere the same way?
Earth still has an active global magnetic field today, so it is far better shielded from solar-wind stripping than Mars is. See the Earth Magnetosphere 3D Explorer to see that active shield rendered directly.
Is the "shield" arc in this scene a real magnetic field simulation?
No - it is a simplified schematic indicator of when Mars had a global magnetic field, not a field-line reconstruction. For an actual rendered dipole field, see the Earth Magnetosphere 3D Explorer.
How does Mars's surface pressure compare to Earth's today?
Mars's average surface pressure today is about 0.6% of Earth's sea-level pressure - a direct result of billions of years of atmosphere loss.