Similarities & Differences in Mars & Earth

By Lexa W. Lee; Updated April 24, 2017
Mars is similar to Earth is some ways, and very different in others.

Earth and Mars are planets positioned next to each other in the solar system. Only Venus is closer to Earth. Although the same materials make up Earth and Mars, they are present in different amounts. The two planets are also thought to have similar origins, although they evolved to become very different. While there are many forms of life on Earth, whether any exists on Mars at all remains a question.


Both Earth and Mars are believed to have condensed out of a massive cloud of hot gases around the sun about 4.6 billion years ago, according to the European Space Agency. Since that time, radioactive decay and the loss of heat following their formation have influenced how they each have evolved. Both planets have dense cores and hard exterior crusts. In addition, water had a role in the history of both.


Mars is nearly twice as large as the moon and a little over half the size of Earth, according to the Center for Mars Exploration. The diameter of Mars is about 4,217 miles, compared to that of Earth, which is about 7,926 miles. In addition, Earth has a mass that is 10 times greater. Because of its much smaller size and mass, Mars cooled at a much faster rate than Earth, following its initial formation. Also, its lower gravity resulted in the faster loss of volatile materials, such as water and gases.

Atmosphere and Water

Mars has a very thin atmosphere that consists mostly of carbon dioxide. Average atmospheric pressure is 7 millibars, compared to 1,013 millibars on Earth. Without much atmosphere to protect it from heat loss, temperatures on Mars are much colder. According to NASA Quest, average temperature in the mid-latitudes are minus 58 degrees Fahrenheit. At night, it can drop to minus 76 degrees, while daytime highs may reach 32.

Although water may once have existed on the surface of Mars, it disappeared long ago for unknown reasons. In comparison, Earth's surface is two-thirds water.


The Earth's outer crust is always moving. It is divided into plates that move laterally. In contrast, Mars' is stable, although there still appears to be some magma flow underground. Its geologic state is thus very different from that of the Earth. Greater stability on Mars results in the preservation of much older features, some dating back to about four billion years.

About the Author

Lexa W. Lee is a New Orleans-based writer with more than 20 years of experience. She has contributed to "Central Nervous System News" and the "Journal of Naturopathic Medicine," as well as several online publications. Lee holds a Bachelor of Science in biology from Reed College, a naturopathic medical degree from the National College of Naturopathic Medicine and served as a postdoctoral researcher in immunology.