Seeing Stars: The Red Planet

Mars varies in brightness over months and years because of its size – it is only half the size of Earth. The planet will dim considerably during 2025. 

Jupiter is also bright at present but this is because it is so big. You could actually fit a line of 20 Mars planets across the face of Jupiter!

Mars gets its red colour because of iron present in the dust that covers the planet. Iron is also what gives rust and our blood its red colour. 

In line with the planet’s colour, the ancient Chinese called it the ‘fire star’ and the Greeks and Romans named the planet after their war gods.

Mars is home to one of the highest mountains and also the deepest and longest valley in the solar system.

The Olympus Mons volcano is roughly 27km high, about three times as tall as Mount Everest, while the Valles Marineris system of valleys, named after the Mariner 9 probe that discovered it in 1971, reaches as deep as 10km and runs east-west for roughly 4,000km, about one-fifth of the distance around Mars and close to the width of Australia.

We have learned a lot about Mars from the past 30 years of Lander, Rover, and Orbiter spacecraft missions. 

In the distant past, water flowed across the planet’s surface and Mars was once a habitable planet, with a thicker atmosphere than it has today. 

Two Rovers – Curiosity and Perseverance – are currently operating on Mars. Both have travelled around 30km each exploring the planet.

Did you know that pieces of Mars have reached Earth, but they haven’t been returned by spacecraft – yet! 

In the distant past, rocks from Mars have been blasted off the red planet’s surface due to an impact and after a considerable time orbiting the Sun, they have entered our atmosphere and landed on Earth as meteorites. More than 300 have been identified as Mars rocks.

Despite being known as a dry, dusty planet, Mars has ice, including small polar caps. Spacecraft have identified more than five million cubic km of ice at or near the surface of Mars. If this melted, it would cover the whole planet in water to a depth of 35 metres. Not so dry after all!