One hypothesis suggests that the greenhouse effect

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One hypothesis suggests that the greenhouse effect may have been further enhanced by clouds or by other gases, such as methane Another hypothesis suggests that the young Sun might not have been quite as dim as is generally assumed A third hypothesis suggests that Mars never had an extended period of warmth, but instead had only intermittent periods of rainfall and warmth, perhaps triggered by the heat of large impacts Why did Mars change? Loss of CO2 and water possibly due to a change in Mar’s magnetic field The magnetic field weakened as the small planet cooled and the core solidified, leaving the atmosphere vulnerable to solar wind particles Like the CO2, water vapor may have been stripped away by the solar wind Mars changed primarily because of its relatively small size Mar’s distance from the Sun also helped seal its fate Climate change from axis tilt Models suggest that liquid water might form just beneath the surface or at rock/ice boundaries on the surface whenever the tilt is greater than about 40 degrees Is Mars habitable? Was habitable some time before about 2 – 3 billion years ago The lack of liquid water means the surface of Mars is not habitable at the current time Is there any evidence of life on Mars?
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