Ancient astronomers were mystified by the Red Planet’s seemingly random movement across the sky, sometimes moving in line with its celestial neighbors (prograde motion) or in reverse (retrograde).
Although Mars and Earth share many similarities, they differ greatly in many aspects.
Atmosphere
Mars has an extremely tenuous atmosphere with pressure that is less than 1 percent that of Earth, comprised mainly of carbon dioxide with small amounts of nitrogen and argon present; furthermore, the Martian sky features dust particles of 1.5 micrometer diameter that give its characteristic yellow tint.
On Mars, surface winds are determined by Hadley cells, named for English scientist George Hadley (1685-1768). When air rises near the equator and flows north and south until about 30 degrees latitude where it sinks and cools before returning toward the equator – with occasional interruption from planet rotation or surface landforms which direct wind flow locally.
Due to these factors, Mars’ surface temperature is relatively low; however, underneath that lies an extremely hot magma layer thought to have formed after a massive impact event millions or billions of years ago. This core of magma may contain lighter elements which contribute to its slow rotation rate as well as weaker gravity than Earth.
Owing to Martian atmosphere limitations, liquid water no longer exists on its surface today; however, evidence exists from orbital pictures showing river deltas and lake beds on Mars; furthermore rovers have discovered rocks formed from water forming minerals; furthermore there are indications that the polar ice caps used to be much larger; while briny waters may occasionally flow seasonally down certain hillsides or crater walls.
Mars stands out in the solar system because of its jet streams, which form and power due to differences in air pressure between its northern and southern hemispheres. These jets may also be affected by high terrain features like mountains that contribute to dust storms. Scientists use computer models of Mars’ atmosphere on various scales – mesoscale models detail large-scale features of its atmosphere while microscale models focus more on smaller phenomena.
Temperature
Mars is much colder than Earth due to its distance from the Sun and thinner atmosphere made up largely of carbon dioxide – 95 percent to be exact! These factors combine to create harsh and dry conditions on this world that has reached temperatures as low as minus 225 degrees Fahrenheit at its poles – though temperatures occasionally can climb above 70 degrees at noon at its equator during summer days!
Mars’ surface is generally dry, dusty, and covered in dirt rich in iron oxide (known as “rust,” giving its reddish hue). Yet large concentrations of ice water exist within its two polar ice caps (Planum Boreum and Planum Australe) while radar data suggests there could be shallow subsurface water throughout middle latitudes too.
Mars’ seasons differ significantly from our own due to its elliptical orbit and tilted axis. When Mars comes closer to our star, its southern hemisphere tilts toward us for a brief summer season; on its farthest journey away it tilts away, producing long winter seasons instead.
Phobos and Deimos, like Earth’s two moons, were discovered by American astronomer Asaph Hall in 1877 and named for Greek mythological gods of war – Ares and Deimos.
Mars can experience very windy conditions. Strong gusts of air can send dust flying into the air, covering surfaces and blocking sunlight from reaching sunlight sources. At times, these winds create dust storms which cover entire regions on Mars; sometimes taking months for it all to settle back down again.
Although Mars does not support life as we know it, scientists believe it once had more liquid water to support life on this planet. Atmospheric pressure and temperature are currently too low for stable surface water formation; however, scientists still hope to find hidden pockets of liquid beneath its surface.
Volcanoes
Researchers were amazed to discover that Mars’ seemingly featureless plain was home to an unexpectedly violent geologic history, with massive amounts of lava emerging from numerous fissures as recently as one million years ago, covering an area nearly the size of Alaska and leading to large flood events with deep channels that eventually formed as result of interplay between water in and below its surface and flood-induced eruptions of volcanic rock.
Scientists suspect most Martian volcanism to be basaltic. Basalt is an extrusive igneous rock composed primarily of iron and magnesium minerals and typically dark gray or black in hue. Erupting from volcanoes as highly fluid flows or via the coalescence of molten clots at fire fountain bases (Hawaiian eruption), basaltic magma with high amounts of silica can form thicker and stickier magma with slower bubble formation rates that prove harder for gas bubbles to escape smoothly resulting in explosive eruptions.
When lava flows over ice, it can cause it to melt and break apart into water and debris, triggering what is known as a phreatic eruption and producing distinctive landforms resembling small volcanic cones or craters. Furthermore, melting ice forms channels down slopes that may have contributed to some of the features observed near Elysium Mons.
Mars is home to some of the solar system’s largest volcanoes, including Olympus Mons – taller than any mountain on Earth! Rising plumes of hot rock from its core have formed these giant peaks over millions of years.
Volcanoes on Mars are 10-100 times bigger than their Earth counterparts and produce longer lava flows due to higher eruption rates and reduced surface gravity, particularly those in Tharsis region which are relatively young and active.
Scientists have examined images of Mars volcanoes to gain a greater understanding of how they formed, while also analyzing chemical data collected by Spirit Rover to ascertain composition and structure of Martian soil. With this information in hand, scientists will be better equipped to create models of its environment as well as pinpoint possible sites for future human exploration on this distant world.
Water
Two years ago, planetary scientists announced the discovery of a large saltwater lake at Mars’ south pole that generated both enthusiasm and some doubt from other scientists. Since then, however, researchers have confirmed the presence of that lake as well as discovered three others; providing valuable new data that will aid in better understanding its role within Mars’ water cycle and how its presence influences its surface environment.
Scientists speculate that Mars once had more water than it has now; however, much of it likely dissipated into space as a result of losing its magnetic field, which kept the atmosphere intact; or perhaps it changed due to variations in Mars’ rock composition.
One of the central mysteries about Mars is whether or not there was ever liquid water on its surface; if this were true, could life ever have emerged on this Red Planet? To understand this further, researchers need more details of its past history.
Mars’ geological history can be divided into three distinct periods, named for regions on its surface: Noachian, Hesperian and Amazonian – with Amazonianism covering at least half its history.
These different time periods were separated by the Late Heavy Bombardment, an intense period of meteorite impacts. Noachian periods are characterized by extensive cratering while Hesperian ones tend to feature relatively fewer. Finally, Amazonian periods were found between 2.9 billion to 3.8 billion years ago.
Similar to Earth, Mars features a dense metallic core encased by a silicate mantle. However, its crust may contain heavier elements, making it more likely to evaporate under heat exposure.
Phobos and Deimos may have formed from asteroids captured by Mars’ gravity; their potato shapes indicate this is unlikely to change with gravity being too weak to keep them spherical. Their proximity makes them visible through telescopes – potentially providing useful guidance when landing humans on its surface in future attempts.