How Much Water Is on Mars Compared to Earth?

Mars is often called the “Red Planet” because of its rusty, dusty surface. But did you know Mars also has water? Not as much as Earth, but enough to make scientists curious. Water is important for life, and finding it on Mars means we might discover signs of past—or even present—life there!

Earth is covered in water, about 71% of its surface is oceans, lakes, and rivers. Mars, on the other hand, is much drier. But scientists have found frozen water at its poles and even some hidden underground. If we compare the two planets, Earth is like a giant water balloon, while Mars is more like a desert with a few ice cubes. So, how much water does Mars really have? Let’s find out!

How Much Water Is on Earth?

Earth is the “Blue Planet” because water covers most of its surface. Here’s how much water we have:

• Oceans hold about 97% of Earth’s water.
• Ice caps and glaciers store another 2%.
• The remaining 1% is in lakes, rivers, and underground.

If we collected all of Earth’s water into a big ball, it would be about 1,386 million cubic kilometers in size. That’s a lot of water!

Fun Fact:

If Earth were the size of a basketball, all its water would fit in a ping-pong ball. But don’t let the small size fool you—that’s still way more than any other planet we know!

How Much Water Is on Mars?

Mars doesn’t have oceans or rivers like Earth, but it does have water in other forms:

• Polar Ice Caps: Mars has thick ice caps at its north and south poles. Most of this is frozen carbon dioxide (dry ice), but some is water ice.
• Underground Ice: Scientists believe there are large amounts of ice buried under Mars’ surface.
• Small Amounts of Liquid Water: Some earlier studies suggested tiny amounts of salty liquid water might flow during warm seasons, but this is debated today.

If we gathered all of Mars’ water, it would be about 5 million cubic kilometers. That’s only 0.03% of Earth’s water!

Comparison:

• Earth’s water = A large swimming pool.
• Mars’ water = Just a few cups from that pool.

Why Doesn’t Mars Have as Much Water as Earth?

Mars was once much wetter, with rivers and lakes. So, where did all the water go? Here are some reasons:

1. Mars Is Smaller: Its gravity is weaker, so water vapor escaped into space over time.
2. No Magnetic Field: Earth’s magnetic field protects our water from being blown away by solar winds. Mars lost its magnetic field long ago.
3. Thin Atmosphere: Mars’ air is too thin to keep liquid water stable. Most of it either froze or evaporated.

Fun Fact:

Billions of years ago, Mars might have had an ocean covering its northern half! But today, it’s just a dry, cold desert.

Could Mars Have More Hidden Water?

Yes! Scientists are still discovering more water on Mars. Here’s where they think it might be:

• Underground Lakes: Radar scans from ESA’s Mars Express suggest the possibility of subsurface liquid water beneath the polar ice, though this is still debated.
• Glaciers: Some areas have glaciers covered in dust.
• Seasonal Flows: Dark streaks on slopes might be salty water melting and flowing.

Future missions, like NASA’s Mars expeditions, will search for more water. Who knows? Maybe one day, astronauts will drink melted Martian ice!

Conclusion

Earth is a water-rich planet, while Mars is mostly dry with small amounts of ice and maybe some liquid water. Billions of years ago, Mars might have had rivers and lakes, but today, it’s a cold desert with frozen water at its poles and underground.

Scientists keep studying Mars to learn more about its water—and maybe even find signs of life! If humans ever live on Mars, they’ll need to use this water to survive. What do you think, could Mars one day have more water again?

📌 Frequently Asked Questions