Mars, on the other hand, has been unprotected because of its lack of magnetic field, and over billions of years, maybe enough atmosphere has been stripped away to account for a transition from a habitable planet to the planet that we see today.
Marte, por otra parte, ha estado desprotegido debido a su falta de campo magnético, y durante miles de millones de años, ha sido despojado de su atmósfera para pasar de planeta habitable al planeta que vemos hoy.