Mars, also known as “the Red Planet”, is the fourth planet from our Sun and often referred to by its nickname. Covered in reddish iron oxide, Mars features canyons, volcanoes and dry lake beds on its rocky surface. Additionally, its thin atmosphere contains carbon dioxide, nitrogen and trace amounts of water and methane gasses – creating an extremely unstable environment on Mars.
Past Mars missions have revealed that its climate once varied widely. Since then, however, it has drastically shifted.
1. History of Mars
Mars formed about 4.5 billion years ago alongside the other rocky planets in our Solar System. It has an iron, nickel and sulfur core; an outer mantle composed mostly of basalt; and a basalt crust rich with iron oxide which gives Mars its characteristic red hue. Robotic rovers have discovered evidence that at one time its atmosphere may have been thick enough for water flow across its surface.
Mars’ surface features both smooth, flat northern plains and rugged southern highlands with numerous craters, featuring vast amounts of underground ice that could still be frozen today. Although Mars lacks an actual magnetic field, its crust does have some magnetism which may have formed very early in its history.
Mars, like Earth, features two small moons called Phobos and Deimos that orbit it regularly. Mars rotates daily; taking approximately 687 days (or 1.88 Earth years) for its full rotation around the Sun.
Mars is much colder than Earth, due to being further away from the Sun, as well as less dense than Earth and less dense objects (such as people) weigh less; for example a person weighing 100 pounds on Earth would only weight 38 pounds due to gravity differences. Furthermore, due to a very thin atmosphere composed mostly of carbon dioxide and trace gases that makes exploring difficult on foot; however robots equipped with cameras and tools have managed to traverse its surface for over 83 sols (sol = sol).
2. Geology of Mars
Orbiters, landers and rovers have provided much insight into Mars’ geology through extensive observations by orbiters, landers and rovers. Geologists use rocks’ age and composition information to reconstruct stories about past environments; geologists have discovered some rocks formed on Mars with water present, suggesting there once existed lakes and seas on its surface.
Mars exhibits a global geologic dichotomy similar to Earth, Venus, and the Moon: old, heavily-cratered highlands in its southern half contrasted by younger, low-lying plains in its northern half – similar to what can be found here on Earth or the Moon or Venus. Furthermore, large impact basins buried deep underground – Hellas and Argyre in particular – further accent this division.
Some areas on Mars’ surface display features that resemble streams – these are known as inverted relief features and it is believed that they were formed when sediments deposited were later eroded upward by wind or water erosion processes, with certain sediments cemented together through minerals dissolved in water, making them more resistant to erosion than loose material deposits.
Other features show that Mars once had an active, dynamic interior. For instance, there are numerous volcanic centers located within Tharsis bulge (shaped like a peanut) which may have resulted from early phases of melting within Mars’ crust; magma possibly moved around under a solid silicate layer and created these features.
Mars boasts one of the solar system’s most intricate systems of tectonic plates, explaining why there are many craters and canyons across its surface – but also why there have been no definitive signs of active plate tectonic activity yet on the Red Planet’s surface.
3. Atmosphere of Mars
Scientific instruments on Mars rovers have revealed evidence of water in its atmosphere. It likely consisted of hydrogen and carbon molecules; such presence being one of the conditions necessary for life on the planet.
Mars’ atmosphere is less than one percent that of Earth, which absorbs and reflects less solar radiation than expected, leading to faster cooling on Mars’ surface than should be the case and leading to thermal tides, in which hot air rises from regions warmed by sunlight while cool air sinks on opposite sides of its planet.
Mars boasts many diverse weather systems that can be divided into three distinct groups. These can be divided into microscale (which occurs locally with no larger impact), global scale, and mesoscale phenomena, the latter of which being driven by the higher concentrations of dust than on Earth.
Mars boasts several other intriguing atmospheric features:
Mars features very high winds and has extreme variations in temperature both day and night, partially as a result of taking longer for it to warm than Earth. Furthermore, due to an elliptical orbit around the Sun which creates distinct seasons lasting approximately three months (quarter of year).
Mars stands out amongst other planets for having no ozone layer, meaning UV radiation from the Sun can easily reach its surface without protection from atmospheric pressure; combined with this fact and low atmospheric pressure levels this makes creating lakes or seas on Mars extremely challenging as any excess liquid would evaporate quickly into space.
4. Climate of Mars
Mars has long held our fascination, inspiring dreams and even scientific studies of its own. Although its current form is one of a sterile frozen desert, evidence suggests that billions of years ago it may have had much more lifelike qualities reminiscent of Earth. Scientists now understand that there may have been rivers, lakes or even oceans containing liquid water on Mars in its past life.
Mars’ climate is heavily determined by solar radiation. Due to a thin atmosphere (100 times thinner than Earth), Mars can’t store heat energy from the Sun effectively and as such experiences temperature fluctuations that range widely.
As the Sun rises and sets on Mars, its heat travels through its atmosphere creating high and low pressure areas, leading to winds which sweep across its surface carrying dust from distant locations before depositing it elsewhere; due to no rainfall being available to wash away this dust.
Another key factor is Mars’ tilted axis, which changes throughout each year. Whichever hemisphere tilts closer to the Sun experiences spring and summer while autumn and winter occur elsewhere on the planet. At two points throughout each year – solstices and equinoxes – both hemispheres receive equal amounts of sunlight.
Scientists also study the formation of polar ice caps on Mars. This helps us gain an insight into its past climate. Polar ice caps consist of carbon dioxide that remains frozen throughout summertime but sublimates, or evaporates directly to gas in wintertime.
5. Surface of Mars
Mars’ surface is composed of rocks and dusty terrain with numerous craters, volcanoes, canyons and polar ice caps. Its thin atmosphere contains mostly carbon dioxide which gives the planet its distinctive reddish hue – hence its moniker as The Red Planet.
Mars is much colder than Earth, with an average temperature of -80F (-60C). Temperatures can drop as low as 195 F at the poles during winter and reach 70 F near its equator during midday hours during summer days.
Mars is covered with a thick blanket of red-tinged iron dust that gives its surface its distinctive red hue. This dust likely covers a crust composed of basalt – an abundant volcanic rock found both here on Earth and the Moon – while below this dust lies an estimated mantle composed of peridotite rocks containing silica, oxygen, magnesium and iron containing mineralizations such as carbon.
Like Earth, Mars experiences seasons, which are caused by changes in sunlight levels reaching its surface. Since Mars tilts relative to the Sun, certain regions receive more direct light at specific times during each year.
Phobos and Deimos, two small moons orbiting Mars, are heavily cratered bodies with orbits roughly six feet closer than that of Earth’s Moon. Scientists suspect it might have captured an asteroid and may one day crash into it or disintegrate, creating an orbiting debris field around Mars.
Mars’ polar regions are covered with an icy mixture composed of carbon dioxide and water ice, known as permafrost. Ice caps form when temperatures are warm enough, only to melt later due to cold weather; this cycle could have occurred for millions of years.