A new image from ESA's Mars Express Orbiter shows exactly how different regions of Mars are from each other. From the cloudy northern polar region all the way down to Helles Planitia down south, Mars is a puzzle of different types of terrains. At the heart of all this is what is known as the Martian Dichotomy.
The north pole of Mars is obscured by clouds, with paths running south to the northern hemisphere. Clouds block the polar region from view, but we know that it is always covered with ice, thicker in winter and thinner in summer. We also know that he is sunk into a cat. The northern hemisphere is 2 km lower than the southern hemisphere. In the ancient past of Mars, the northern hemisphere may have been covered with water.
The Northern Hemisphere is characterized by low-lying plains without many impact basins. This makes scientists think that he is much younger. It certainly looks younger to the southern hemisphere, which is heavily marked by all crater sizes.
The ordinary geography that dominates the northern hemisphere is called the Vastitas Borealis and is wrap around the world. Mars topographic map puts it in focus.
A rough strip of terrain separates the northern hemisphere of Mars from its southern hemisphere. The group has flat meats, rocks, breaks, canyons and valleys. Scientists believe that many of these features were carved out of water and ice, while some were likely to be carved out by lava flows from Mars' massive volcanoes.
One representative area of this strip of terrain is called Cydonia Mensae, a very studied region. It contains the infamous "Face of Mars", which looks like a human face.
The northern plains just below the polar cap are dark gray and dusty. Together with the prominent escarpment, they create a dark ray on the surface of the planet's mostly yellow-brown color. Traveling south are the huge orange mountains marked by bony craters of all sizes. Scientists believe that the southern mountains are ancient and that some of these craters date to the earliest history of the planet.
The part of the southern mountains visible in the main image is Arabia Terra (upper left) and Terra Sabeya (middle and lower right). At the bottom and almost out of view is the massive Hellas Planitia, a large plain in the interior of Hellas Elasian Basin
The Martian dichotomy, the split between the northern and southern terrains is one of the Greatest Mysteries of Mars. that the two regions are so different? What caused the discrepancy?
Mars may have had tectonic plates similar to Earth in its past, and perhaps some geological processes in the mantle of the planet are responsible. A combination of factors, perhaps.
The one-off hypothesis has been reinforced in recent years as we become better and better looking on Mars. One of the signs against him is that an impact of the magnitude needed would obscure large parts of Mars in a discard. But there is no evidence of this on the surface. On the other hand, if this happened long enough, perhaps as much as 4.5 billion years ago, erosion could remove evidence of this blanket.
The Martian dichotomy could have been created by some sort of plate tectonics that moved massive amounts of material on the planet. As our understanding of this process on Earth is still very limited, this complicates assumptions about the same Mars processes. But it is possible that the cells or jets of material from the mantle of the planet have risen to the surface in one hemisphere while the material has faded into the other. But since there is no observed evidence of plate tectonics on Mars, this is unlikely.
It is even hypothesized that many major impacts create a dichotomy. But the problem with all these suggested explanations for the dichotomy is that we just don't have enough evidence. Neither to confirm it, nor to really exclude it. Maybe the NASA InSight Lander will shed some light.
Currently, Mars has six orbits, and the curiosity rover and the InSight lander are on the surface. And several other missions are planned.
Over time, our scientific knowledge of Mars will continue to grow and ultimately, perhaps in the very distant future, we will solve the Martian dichotomy.