Mars 101 | National Geographic

[Music] The Babylonians called it Nargal; the Hindus called it Mongala; the Egyptians called it Harder or the Red One. Today, we know it as the Red Planet. For centuries, Mars has aroused our imaginations. The world's best scientists and people everywhere have asked themselves: Did life exist on Mars? And could Mars support life in the future?

But what is Mars made of, and could humans ever live there? This is Mars 101. Mars is the fourth planet from the Sun. While Earth is 93 million miles away from the Sun, Mars is some 49 million miles further away. The combination of added distance and the elliptical orbit of Mars means that one year on the Red Planet lasts 687 days.

While orbiting the Sun, much like Earth, Mars has a tilt in its axis. This means Mars gets seasons like we do, but due to its elliptical orbit, some of its seasons last longer. Temperatures can reach as low as 284°F, but due in part to the Red Planet's distance from the Sun, the average temperature on Mars is a chilly 81°F.

Another key difference is gravity. The gravitational pull is much weaker on Mars, about 62% less. That means that someone who weighs 100 lbs here on Earth would only weigh 38 lbs on Mars. Mars is about half the size of Earth, but the land mass is similar. Because Mars lacks the key ingredient to supporting life—water, or at least bodies of water—back in the day, around 3.5 billion years ago, Mars had a warm and thick atmosphere that allowed oceans of water to exist.

Nowadays, Mars is a frigid and arid desert world, with no signs of life, at least on the surface. But new data from NASA's reconnaissance transmission shows evidence that liquid water does likely flow intermittently on the Red Planet. Another key ingredient to support life is oxygen. On Earth, our atmosphere is made up of 21% oxygen and 78% nitrogen. On Mars, it's hard to come by oxygen at all; 96% of Mars's atmosphere is carbon dioxide.

With a population of over 7 billion people and climate change threatening the future of our planet, Mars could be a potential future host planet. But don't buy your one-way ticket to Mars just yet. The Red Planet is far from being hospitable to humans. You must first survive the one-year one-way trip to get there.

Once you arrive, scientists estimate that without a proper space suit, humans would die in minutes, if not seconds. The low atmospheric pressure would rupture your internal organs and skin, and the lack of oxygen, cold surface temperatures, irritating dust, intense UV radiation, surface chemicals, and oxidants would ensure you die a painful death.

Despite all this, NASA recently announced Journey to Mars, an unprecedented plan that would put humans on Mars by 2030, with proper space suits, mind you. Although we know a lot more about Mars than we ever did, scientists around the world continue to study the planet and deploy missions like Mars Exploration Rover Spirit, Curiosity, and reconnaissance to better understand the planet and maybe one day find life on it or make it our second home.