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What are the atmospheres of Mars and Pluto like?

I am in 8th grade and we are currently learning about the solar system. I was wondering if you could please tell me if you could tell me what the atmosphere is like on Mars and also on Pluto? Thank you!

The atmosphere of Mars is made up of 95% carbon dioxide, 3% nitrogen and 1.6% argon. To compare, the Earth's atmophere is made of 78% nitrogen, 21% oxygen and 1% argon. What's the big difference? Life. The plants on earth convert carbon dioxide to oxygen, which is why our planet has so much of it. Mars' atmosphere is also much thinner than ours. The surface pressure on Mars is only 0.7% of the average surface pressure at sea level on Earth. This means that there is much much less gas in Mars' atmosphere. The atmospheric pressure also changes seasonally on Mars, because the temperature is cold enough (about -65 C) that some of the carbon dioxide freezes (actually it 'sublimes,' or goes straight from gas to solid) during the winter and "snows" onto the polar cap. This means there's dramatically less carbon dioxide left in the atmosphere. During the summer, when the polar cap warms up again, the carbon dioxide goes back into the atmosphere. Mars also has a lot of dust in its atmosphere, and winds create large dust storms.

Not very much is known about Pluto's atmosphere because it is very far away, and no spacecraft has visited it yet, whereas Mars is the most visited planet besides Earth. Pluto's atmosphere is made up of mostly nitrogen and some methane, and is very very thin - it has 100,000 times less gas in it than Earth's atmosphere. Pluto's temperature fluctuates between -235 and -170 C, depending on how close it is to the sun, and when it is warmer, some of the nitrogen ice on its surface evaporates and goes into the atmosphere. Recently, researchers have found that Pluto's atmosphere is getting thicker and its temperature a little warmer, which is very exciting!

March 2003, Cathy Jordan (more by Cathy Jordan) (Like this Answer)

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