Mars: More strange than you think

I don‘t know about you but planets always captivated me. Sure, younger I was big on astronomy but even to my young mind planets had a special place. Just thinking about all the weird details we learn about them each year shows us just how special our own Earth is. Historically, I am definitely not alone in that fascination. Since times immemorial, myths, stories and speculations abound on our neighbors even more so for our closest - Mars. Today, I want to share my love for the Red Planet. I hope that these bite-sized facts will spark your interest and convince you that you should look up from your nose from time to time. Let‘s begin.

Close sibling

Before pointing out how Mars differs from our home, I should show how it is shockingly similar in many ways - more so than you probably think. Just how it moves is similar. In the solar system, revolution times (that is the time it takes for a planet to spin 360 degrees) vary significantly. It goes from a few hours for the erratic Mercury to hundreds of years for Venus. But, for its part, Mars‘ revolution is almost the same as ours. A Martian day is about 24 hours and 37 minutes. An Earth Day is about 23 hours and 56 minutes (yes, not exactly 24 hours). That‘s just a difference of 38 minutes, the smallest difference between planets in the solar system. What‘s more, Mars's axis is inclined (about 30 degrees), another trait it shares with Earth. This means that Mars experiences 4 seasons, just like us. This is, again, an oddity in the solar system. Mars even has polar caps which recess and grow with the seasons. On that note, when the polar caps recess, the melt leads to an apparent darkening when looking at Mars from a telescope. This was thought to be evidence of vegetation and, ergo, proof of life on Mars in the middle-to-late 19th century. There was even a whole debate about deliberate canals on the surface of Mars. Although unfounded, these were critical to the development of the following wave of Mars-centered science fiction (think E. R. Burroughs or H.G. Wells).

Sure Mars does differ in some ways from Earth. It's only about half the size of Earth. His iconic red colour is due to ferric oxide dust - rust dust - which is (fortunately) rarer on Earth. Yet, when we look at other planets, we should be surprised that our closest neighbour is that similar to us. We even share from time to time with him: us with our space missions, it with meteorites. Indeed, as of 2006, 37 meteorites on Earth are confirmed to be of martian origin. Food for thought.

Delinquent children

One way we clearly differ from Mars is with moons. Our own moon is round, predictable and, most of all, enormous. Mars is not that lucky. First, Mars has two moons: Phobos and Deimos. These names are synonymous with dread and terror, which is fitting. These small, malformed rocks are a lot more active than our moon. Take Phobos: it does 3 full rotations around Mars every Martian day. More importantly, it is getting slowly closer to Mars each year - about 1.8 meters per century. Astronomers estimate that in 50 million years, it will either crash on Mars or be torn by smaller rocks orbiting Mars. In contrast, our moon is getting farther away from us each year - about 3.8 meters per century. We should be grateful for our moon while we still have it (for a long while to be sure, but still).

Mars dichotomy

But Mars itself is not as “clean-looking“ as Earth. Don‘t get me wrong, Earth is not a perfect sphere (a subject worth its post) but Mars is another matter. Mars is famous in the field for its dichotomy. In a word, Mars's northern hemisphere is drastically different than the southern. The southern hemisphere is on average 2 km higher than the northern hemisphere with a crust thickness almost doubled (58 km versus 32 km). On accurate telescopes, this makes Mars look a bit like a cooked egg still in its lower shell. This leads to drastically different environments. The northern lowlands are arid but relatively calm and flat. Meanwhile, the southern highlands are plagued with dust storms (some lasting years) and volcanoes. Seasons are also quite different up north than south.

This difference is so dramatic that researchers have theorized about the origin of the dichotomy for some time now. Some think it might have resulted from tectonic plate movement. Others that it was caused by a large impact or many smaller ones. Either way, researchers agree that this dichotomy is linked to our next subject.

The Tharsis region - Hell… on Mars

Next and last on our list is the infamous Tharsis region. Tharsis is pretty much a hellscape - known for the absurd number of volcanoes on it. Some even theorize that the region itself could be defined as a single volcano. What‘s more that region has moved over time, starting in the northern hemisphere and reaching the equator in about 4 billion years. In any case, Tharsis‘ volcanoes are huge - ridiculously huge. Simply put: we don‘t have anything even close to it on Earth. Tharsis Monte is a great example. Tharsis Monte is a subregion of 3 large volcanoes: Pavonis Mons, Arsia Mons and Ascraeus Mons. They all dwarf Mont Everest and it's not even close. Their diameter ranges from 375 km to 475 km and the highest (Ascraeus Mons) is 18 km high. Mount Everest is less than 9 km high. That‘s right: stack to Everest on top of each other. What‘s even more ridiculous is that Ascraeus Mons is not even the highest volcano in the Tharsis region. That honour goes to Olympus Mons - the highest mountain in the solar system full stop. It stands at an absurd 22 km high. Unbelievable.

Going back to Earth

But for now, let‘s go back to much more comfortable ground. As you can see, Mars has enough oddities to fill pages and pages more. I do hope that this short post convinced you that it is worth it to seek further than your everyday concerns - not just up there but also all around us. Stay curious. Keep exploring.

And see you next time.

References

Andrews-Hanna, Jeffrey C.; Zuber, Maria T.; Banerdt, W. Bruce (2008). "The Borealis basin and the origin of the martian crustal dichotomy". _Nature_.
Barlow, N. (2008). _Mars: An Introduction to its Interior, Surface, and Atmosphere_. Cambridge University Press, https://archive.org/details/marsintroduction0000barl/page/n9/mode/2up