Is Mars Bigger Than Earth?

Occasionally, a reader asks ”is Mars bigger than Earth?”. No, Mars is about one half of the size of Earth. Below is a comparison chart so the you can get an idea of how much smaller Mars is than Earth

Earth Mars
Diameter 12,742 km 6,792 km
Surface Area 510,072,000 km2 144,798,500km2
Volume 1.08321×1012km3 1.6318×1011km3
Mass 5.9736×1024kg 6.4185×1023kg

The diameter of Mars is about 53% of Earth’s and the surface area is close to 38% of Earth’s. When you put the numbers into a percentage, the surface area really seems small, but it is equal to all of the dry land on Earth. Scientists have found evidence of ancient liquid water on Mars. That means there were rivers and, possibly, oceans on the Red Planet. Imagine how small the available living space would have been then. Couple that with Mars having several of the tallest mountains and the deepest canyon in the Solar System and you realize exactly how little usable surface there really is on the planet.

Mars is the number one planet that scientists will mention when they are talking about terraforming. Transforming Mars would take centuries. Christopher McKay of NASA Ames Research Center believes that the key steps would be, first, releasing greenhouse gases to thicken the Martian atmosphere. This will help the planet retain heat from the Sun while filtering its radiation. The increased temperature would vaporize some of the carbon dioxide trapped in and on the planet’s surface. The CO2 will increase the greenhouse effect, warming the planet even more. The temperature could increase by as much as 70 degrees on the Celsius scale. The increased temperature will melt the subsurface water ice on Mars, creating rain, rivers, and lakes. The water vapor from this release would also increase the atmospheric pressure to a level equivalent to what is seen at high elevations here on Earth. After all of these steps, the air would still be 90% carbon dioxide or higher. This is when plant life would be introduced to convert some of that carbon dioxide into oxygen. While humans could occupy the planet as the plants are being introduced, it would be several centuries before they would be able to remove their oxygen masks.

The answer to ”is Mars bigger than Earth” is no. The planet may be minute compared to Earth, but it is seen as a world full of potential by scientists. It is the most studied planet other than Earth, so be sure to look around for more information on the Red Planet.

We’ve written many articles about Mars for Universe Today. Here’s an article with some interesting facts about Mars, and here’s the distance from Earth to Mars.

If you’d like more info on Mars, check out Hubblesite’s News Releases about Mars, and here’s a link to the NASA Mars Exploration home page.

We’ve also recorded an episode of Astronomy Cast all about Mars. Listen here, Episode 52: Mars.