"The name is well earned" means that

Mars, the fourth planet from the Sun, is often called the Red Planet. The name is well earned: its ground is full of iron that has rusted, and rust is red. Seen from the Earth, even without a telescope, it glows a dull orange-red, which is why people have known it since ancient times.

In many ways Mars looks like a smaller, colder version of our own world. It is about half the size of the Earth. It has seasons, ice caps at its poles, volcanoes, deep canyons and weather, with clouds and winds. Sometimes the wind lifts the red dust into storms so large that they cover the whole planet.

But it would be a hard place to live. Mars is a freezing desert, with an average temperature far below the freezing point of water. Its air is very thin and made mostly of carbon dioxide, so people could not breathe it. There are signs that floods once ran across its surface, but today most of its water is locked in icy soil and thin clouds.

A day on Mars is only a little longer than ours, at about 24.6 hours. Its year, though, lasts 687 Earth days, almost twice as long as a year on Earth.