Why is Mars referred to as the Red Planet?

Why is Mars known as the Red Planet?

Even with the naked eye, most of the surface of Mars looks rusty red in colour. And areas that look green are in fact red, an optical illusion caused by contrasting light and dark areas.

Astronomers have given many explanations for these various colours. Some argued that the green areas were vegetation and red regions were oceans. Then, in 1934, American astronomer Rupert Wildt gave a new theory: the browns, yellows and reds on Mars came from iron oxide rust. Examine a rusting corrugated iron roof, and you will see iron oxide in many of its colours.

When the Viking 1 and Viking 2 spacecraft landed on Mars in 1976, their instruments scooped up and analysed surface material. They proved that Wildt’s theory was indeed right. Mars is covered with rusty, red sand, which is often whipped 30 km (nearly 20 miles) high by winds blowing at more than 100 km/h (62 mph).

These intense storms occur particularly when Mars is closest to the Sun, and the planet may be hidden by dust for months. When the dust settles, it is thoroughly mixed, giving Mars a surface of almost uniform rusty redness.