<img src="https://d5nxst8fruw4z.cloudfront.net/atrk.gif?account=iA1Pi1a8Dy00ym" style="display:none" height="1" width="1" alt="" />
Skip Navigation


Mars, the planet we know best, has interesting surface features including evidence for running water.

Atoms Practice
Estimated2 minsto complete
Practice Mars
This indicates how strong in your memory this concept is
Estimated2 minsto complete
Practice Now
Turn In
Imagine Earth with No Atmosphere

Imagine Earth with No Atmosphere

Source: http://www.jpl.nasa.gov/spaceimages/details.php?id=PIA02653
License: CC BY-NC 3.0

Before Mariner 5 flew by Mars is 1965, humans thought that the red planet was a welcoming world with water and vegetation; maybe even more advanced life forms. Mars may once have been hospitable, but it isn’t today. What happened?

Why It Matters

Credit: NASA
Source: http://en.wikipedia.org/wiki/File:Mars_atmosphere.jpg
License: CC BY-NC 3.0

The thin Martian atmosphere can be seen on the horizon [Figure2]

  • Early in the history of the solar system, Mars had liquid water that moved across the planet.
  • Currently Mars has a thin atmosphere; it is cold and has no obvious life.
  • If there is life on Mars, it is microbial and it lives under the soil.

Can You Apply It?

With the link below, learn more about Mars. Then answer the following questions.

  1. Why was Mars warm enough to have liquid water early in the history of the solar system?
  2. Why do scientists think Mars had a significant atmosphere 4 billion years ago?
  3. Which gases would have had to have been in the atmosphere and why?
  4. How did Mars lose its atmosphere and when?
  5. What is the evidence for the previous answer?
  6. How will the spacecraft MAVEN determine how much carbon dioxide was lost to space in the past 4 billion years?

    Notes/Highlights Having trouble? Report an issue.

    Color Highlighted Text Notes
    Please to create your own Highlights / Notes
    Show More

    Image Attributions

    1. [1]^ Credit: NASA/JPL/MSSS; Source: http://www.jpl.nasa.gov/spaceimages/details.php?id=PIA02653; License: CC BY-NC 3.0
    2. [2]^ Credit: NASA; Source: http://en.wikipedia.org/wiki/File:Mars_atmosphere.jpg; License: CC BY-NC 3.0

    Explore More

    Sign in to explore more, including practice questions and solutions for Importance of the Atmosphere.
    Please wait...
    Please wait...
    Add Note
    Please to create your own Highlights / Notes