The Solar System

What is the atmosphere on Mars like?
Answered by Jessika Toothman and Science Channel
  • Jessika Toothman

    Jessika Toothman

  • Science Channel

    Science Channel

  1. The atmosphere surrounding Mars is much less dense than Earth's -- more than 99 percent less dense on average, although the actual PSI varies depending on a number of factors. Altitude is one. At the lowest point on Mars, the pressure is usually around 9 millibars; up on Olympus Mons, it's only around 1 millibar. The atmosphere is about 95 percent carbon dioxide, and the rest consists of nitrogen, argon and very small amounts of oxygen, water vapor and trace amounts of other gasses like neon, krypton, xenon, ozone and methane.

    Temperatures tend toward the frigid side; most of the year the majority of the planet experiences temperature well below freezing (lows are down to around -220 degrees Fahrenheit or -140 degrees Celsius). All that carbon dioxide in the atmosphere doesn't pack much punch in terms of the greenhouse effect, either. The atmosphere only raises the temperature by about 40 degrees Fahrenheit (5 degrees Celsius) as opposed to how cold the planet would be if it lacked an atmosphere altogether.

    Despite being so insubstantial --perhaps due to the fact that Mars does not have a magnetosphere -- Mars' atmosphere does support wind and massive dust storms are common. The airborne dust particles are also what give Mars its red skies. When light from the sun reaches Mars, those particles scatter the light to a greater degree than how they're scattered on Earth, so instead of seeing blue you see red.

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  2. The atmosphere on Mars is very different from that of planet Earth. For one thing, more than 95 percent of Martian atmosphere is carbon dioxide. Mars has very little oxygen (about 0.13 percent) and only a little nitrogen (2.7 percent). It has a minuscule amount of water vapor and a mere seven millibars of atmospheric pressure. Just to give you an idea, planet Earth has an atmospheric pressure of 1,000 millibars. The atmosphere on Mars is very thin, so it doesn't retain heat. The only heat on this cold planet comes from the sun's radiation that has been absorbed into the ground. Because the atmosphere is so thin, the temperatures swing radically, with a difference of about 100 degrees Fahrenheit (or 60 degrees Celsius) between the daily highs and lows. This thin atmosphere also contributes to seasonal changes -- with carbon dioxide evaporating into the atmosphere in summer and carbon dioxide "snow showers" in the winter.

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