Mars can be seen with the naked eye throughout most of the year and becomes easier and brighter to identify during oppositions, when Earth and Mars come closest together on their orbital paths around the Sun.
Planet Earth’s surface is reddish brown in hue and covered with black volcanic sand and dark basalt rocks that punctuate its arid valleys and escarpments.
Galileo made the first telescopic observations of Mars in 1610. Giovanni Virginio Schiaparelli later created the first modern map of Mars with indications of interconnecting systems of straight lines on bright areas he called canali (Italian for channels).
Percival Lowell established an observatory in Flagstaff, Arizona during the late 19th century specifically to study Mars. Through these efforts he was able to determine that its rotation period is 24 hours and 40 minutes and that there are four seasons on Mars.
At Mars’ surface, wind circulation is determined by Hadley cell motion – named for English scientist George Hadley (1685-1768). Rising air near the equator moves one part northward and one part southward at surface levels until cooling and sinking takes place preventing direct movement across latitudes. Instead, wind patterns are directed by topography and surface landforms to create regional circulation patterns that steer away from direct movement across latitudes.
Mars’ polar caps feature seasonal ice sheets that dwarf those on Earth, covering an area roughly equivalent to Alaska. Like Earth, however, Mars also has an uneven tilted axis which causes its exposure to sunlight to vary across its surface.
Mars’ atmosphere is less complex than Earth due to the absence of oceans, with global average temperature estimated at minus 153 degrees Fahrenheit but temperatures can range widely depending on time of year or location – though temperatures typically decrease as altitude does increase; although notable exceptions exist. NASA’s Curiosity rover touched down at Yellowknife region on Aug 5; its name honoring Canada’s capital which historically served as a starting point for mapping of some of its oldest rocks.
Comparative to Earth, Mars has a much thinner atmosphere due to early loss of carbon dioxide and other gases to space or ground sources (rock formation). Air pressure on Mars also varies over time and location, which has an impactful impact on what gases make up its atmosphere: CO2, water vapor, nitrogen and argon; further composition can be changed by UV light which breaks apart H2O molecules to release carbon monoxide and ozone into its surroundings.
Mars’ atmosphere is constantly shifting and evolving as we discover more of what its past looked like. Dust storms play an integral part in shaping its atmosphere; some of the largest occur during southern summer and autumn when Mars is closest to the Sun; these dust storms have global reach driven by Hadley circulation which mirrors trade winds here on Earth.
Mars’ light gravity makes its atmosphere susceptible to pressure from solar wind particles emitted by our Sun. Over millions of years, this pressure stripped lighter molecules away from Mars’ atmosphere and began thinning it out over time; something NASA’s MAVEN mission is currently researching.
Most scientists believe that Mars initially began with a thicker atmosphere rich in hydrogen and carbon dioxide. This would have fostered a temperate climate suitable for liquid water to exist on Mars as well as potentially supporting microbial life – something known to exist on Earth around hydrothermal vents or fissures in ocean floor, although we don’t yet know which conditions on Mars or anywhere else would support such microbes.
Mars is much colder than Earth because of its thin atmosphere that retains less heat, coupled with being further away from the Sun. These factors combine to produce temperatures ranging from minus 195 F (minus 125 C) at its poles during winter to an agreeable 70F (20C) nearer the equator during midday hours.
Mars shares Earth’s four seasons, but each one lasts for longer due to its more elliptical orbit and Jupiter’s influence – this explains why Mars does not always come close enough for great viewing with telescopes or naked eyes.
Mars’ axis of rotation is tilted from its direction relative to the Sun; this phenomenon is known as its obliquity, and may range anywhere from near zero – when seasons don’t exist – up to 45 degrees when seasonal differences become extreme.
One major distinction between Mars and Earth is the lack of moving tectonic plates on Mars, meaning volcanoes like Olympus Mons will continue to build over the same hot spot for their entire lifetimes. Dust loss from the atmosphere on Mars is more difficult because there’s no precipitation on its surface to wash it away; windy weather creates series of high and low pressure areas known as baroclinic circulation which causes dust particles to rise into the air before disseminating across its surface – similar to how Earth generates trade winds do this process.
There’s evidence of liquid water once flowing and pooling on Mars, but only life capable of using hydrogen and carbon dioxide as energy could survive here. Even then, its lifespan likely would only have been billions of years before climate changed to cold and dry environments.
Mars’ surface is covered with dust that occasionally bursts forth as large dust storms, creating conditions similar to Mount Olympus where volcanic activity would increase with time, increasing eruption height. Scientists have noted signs of volcanic activity on Mars such as some areas that seem highly magnetized indicating they once contained magnetic fields.
One unique aspect of Venus is that there are no moving tectonic plates like on Earth, meaning a volcano that forms over geothermal hot spots will likely remain there throughout its lifespan. This may explain why Olympus Mons has grown so high over time–each eruption has added height to it like pruning trees grow larger year by year.
Mars’ red hue can be attributed to its dusty atmosphere and iron-rich rocks in its crust. But that isn’t its only source of hue; Phobos and Deimos, two small moons believed to have formed from captured asteroids, orbit the planet at an approximate distance twice that between Earth and Sun.
People have long speculated about whether Mars had life. Early astronomers lamented its capricious motion through space – sometimes moving in line with other stars (direct prograde motion) or in opposite direction (retrograde). Finally in 1609 German astronomer Johannes Kepler provided evidence that Mars followed an elliptical orbit and used gravitation to dictate its nonuniform but predictable movements.
Mars, being a planet with plenty of water, once had an ocean known as Oceanus Borealis that covered most of the southern half of its surface around 4.1 to 3.8 billion years ago due to specific planetary conditions. Over time however, temperature variations and changes to how Martian crust formed caused it all the water in its atmosphere to seep into its ground layer where up to 99% was embedded within rock called hydrous minerals that contain hydrogen and oxygen as its constituent elements.
Today, remnants of that water can still be seen on Mars, though mostly as carbon dioxide and ice deposits. We can even detect changes in its seasonal distribution.
Scientists have also detected methane on Mars. Although we cannot see or smell it directly, the Mars Odyssey orbiter detects it every four-and-a-half hours when dipping into its atmosphere.
Methane production likely results from chemical reactions involving water and heat, such as serpentinization or pyrite formation, among others. Other possible sources are rock-water reactions or breaking down of sulfides and carbonates into hydrogen gas; since methane levels spike at different times throughout the year, scientists speculate it is released through seasonal processes.