In what way is Mars similar to Earth

At one time, astronomers believed the surface of Mars was crisscrossed by canal systems. This in turn gave rise to speculation that Mars was very much like Earth, capable of supporting life and habitation to a native civilization. Only as human satellites and rovers began to behave flybys and surveys of the planet, this vision of Mars quickly dissolved, replaced by one in which the Red Planet was a common cold, desiccated and lifeless world.

However, over the past few decades, scientists accept come to learn a great bargain about the history of Mars that has altered this view as well. We now know that though Mars may currently be very cold, very dry, and very inhospitable, this wasn't always the case. What's more than, we take come to run into that even in its electric current course, Mars and World actually have a lot in common.

Between the two planets, there are similarities in size, inclination, structure, limerick, and even the presence of water on their surfaces. That beingness said, they too have a lot of central differences that would make living on Mars, a growing preoccupation among many humans (looking at you lot, Elon Musk and Bas Lansdorp!), a significant claiming. Let's go over these similarities and the difference in an orderly manner, shall nosotros?

Sizes, Masses and Orbits:

In terms of their size and mass, Earth and Mars are quite different. With a mean radius of 6371 km and a mass of 5.97×10²⁴ kg, Globe is the fifth largest and fifth virtually-massive planet in the Solar System, and the largest of the terrestrial planets. Mars, meanwhile, has a radius of approximately 3,396 km at its equator (3,376 km at its polar regions), which is the equivalent of roughly 0.53 Earths. However, it'south mass is merely 6.4185 10 10²³ kg, which is effectually 10.7% that of Earth'southward.

Artistic representation of the orbits of Earth and Mars. Credit: NASA

Similarly, Globe's book is a hefty 1.08321 10 ten¹² km³, which works out i,083 billion cubic kilometers. Past comparison, Mars has a volume of 1.6318 x ten¹¹ km³ (163 billion cubic kilometers) which is the equivalent of 0.151 Earths. Between this deviation in size, mass, and volume, Mars'south surface gravity is 3.711 m/s², which works out to 37.half dozen% of Earths (0.3761000).

In terms of their orbits, Earth and Mars are also quite different. For instance, Globe orbits the Sun at an average distance (aka. semi-major centrality) of 149,598,261 km – or one Astronomical Unit of measurement (AU). This orbit has a very small eccentricity (approx. 0.0167), which means its orbit ranges from 147,095,000 km (0.983 AU) at perihelion to 151,930,000 km (1.015 AU) at aphelion.

At its greatest distance from the Sun (aphelion), Mars orbits at a distance of approximately 249,200,000 km (1.666 AU). At perihelion, when information technology is closest to the Lord's day, it orbits at a altitude of approximately 206,700,000 km (1.3814 AU). At these distances, the Earth has an orbital flow of 365.25 days (one.000017 Julian years) while Mars has an orbital flow of 686.971 days (1.88 Earth years).

However, in terms of their sidereal rotation (fourth dimension it takes for the planet to consummate a single rotation on its axis) World and Mars are again in the same boat. While World takes precisely 23h 56m and iv s to complete a single sidereal rotation (0.997 Earth days), Mars does the same in about 24 hours and forty minutes. This means that one Martian day (aka. Sol) is very close to single 24-hour interval on Earth.

Earth's centric tilt (or obliquity) and its relation to the rotation axis and plane of orbit. Credit: Wikipedia Commons

Mars'due south centric tilt is very similar to Globe'due south, being inclined 25.nineteen° to its orbital plane (whereas Globe's axial tilt is only over 23°). This means that Mars also experiences seasons and temperature variations similar to that of Earth (see beneath).

Construction and Limerick:

Earth and Mars are similar when it comes to their basic makeups, given that they are both terrestrial planets. This ways that both are differentiated between a dense metal core and an overlying mantle and crust composed of less dense materials (like silicate stone). However, World's density is higher than that of Mars – 5.514 g/cm^three compared to 3.93 g/cm³ (or 0.71 Earths) – which indicates that Mars' cadre region contains more than lighter elements than World'south.

World's core region is fabricated up of a solid inner core that has a radius of about i,220 km and a liquid outer cadre that extends to a radius of about 3,400 km. Both the inner and outer cores are composed of atomic number 26 and nickel, with trace amounts of lighter elements, and together, they add to a radius that is as large equally Mars itself. Current models of Mars' interior suggest that its core region is roughly  1,794 ± 65 kilometers (1,115 ± 40 mi) in radius, and is composed primarily of iron and nickel with nigh 16-17% sulfur.

Both planets have a silicate mantle surrounding their cores and a surface chaff of solid material. Earth's mantle – consisting of an upper mantle of slightly glutinous material and a lower mantle that is more solid – is roughly 2,890 km (1,790 mi) thick and is composed of silicate rocks that are rich in iron and magnesium. The Earth's crust is on boilerplate xl km (25 mi) thick, and is composed of rocks that are rich in iron and magnesium (i.e. igneous rocks) and granite (rich in sodium, potassium, and aluminum).

Artist's impression of the interior of Mars. Credit: NASA/JPL

Insufficiently, Mars' mantle is quite sparse, measuring some 1,300 to ane,800 kilometers (800 – i,100 mi) in thickness. Like Earth, this mantle is believed to be composed of silicate rock that are rich in minerals compared to the crust, and to be partially viscous (resulting in convection currents which shaped the surface). The crust, meanwhile, averages about 50 km (31 mi) in thickness, with a maximum of 125 km (78 mi). This makes it about three times as hick as Earth'south crust, relative to the sizes of the two planets.

Ergo, the two planets are similar in composition, owing to their common status as terrestrial planets. And while they are both differentiated between a metallic core and layers of less dense material, in that location is some variance in terms of how proportionately thick their respective layers are.

Surface Features:

When information technology comes to the surfaces of Earth and Mars, things once over again get a case of contrasts. Naturally, it is the differences that are most apparent when comparing Bluish Earth to the Red Planet – as the nicknames would suggest. Unlike other planet's in our Solar Organization, the vast majority of Earth is covered in liquid water, about 70% of the surface – or 361.132 1000000 km² (139.43 million sq mi) to be exact.

The surface of Mars is dry, dusty, and covered in clay that is rich iron oxide (aka. rust, leading to its cerise advent). Nevertheless, large concentrations of water ice water are known to be within the polar ice caps – Planum Boreum and Planum Australe. In add-on, a permafrost mantle stretches from the pole to latitudes of about threescore°, pregnant that ice water exists beneath much of the Martian surface. Radar data and soil samples have confirmed the presence of shallow subsurface water at the eye latitudes every bit well.

As for the similarities, Globe and Mars' both have terrains that varies considerably from place to identify. On Earth, both above and below body of water level, there are mountainous features, volcanoes, scarps (trenches), canyons, plateaus, and abyssal plains. The remaining portions of the surface are covered past mountains, deserts, plains, plateaus, and other landforms.

Mars is quite similar, with a surface covered by mountain ranges, sandy plains, and even some of the largest sand dunes in the Solar System. It too has the largest mountain in the Solar Arrangement, the shield volcano Olympus Mons, and the longest, deepest chasm in the Solar System: Valles Marineris.

Earth and Mars have too experienced many impacts from asteroids and meteors over the years. Yet, Mars' own touch craters are far better preserved, with many dating back billions of years. The reason for this is the depression air pressure and lack of atmospheric precipitation on Mars, which results in a very irksome rate of erosion. However, this was non always the case.

Mars has discernible gullies and channels on its surface, and many scientists believe that liquid water used to flow through them. By comparison them to similar features on Globe, it is believed that these were were at least partially formed by h2o erosion.  Some of these channels are quite big, reaching 2,000 kilometers in length and 100 kilometers in width.

Colour mosaic of Mars' greatest mount, Olympus Mons, viewed from orbit. Credit NASA/JPL

And then while they look quite different today, Globe and Mars were in one case quite similar. And like geological processes occurred on both planets to give them the kind of varied terrain they both currently have.

Atmosphere and Temperature:

Atmospheric pressure and temperatures are some other manner in which Earth and Mars are quite different. World has a dense atmosphere equanimous of five main layers – the Troposphere, the Stratosphere, the Mesosphere, the Thermosphere, and the Exosphere. Mars' is very sparse past comparing, with pressure level ranging from 0.four – 0.87 kPa – which is equivalent to about i% of Earth'south at ocean level.

Earth's atmosphere is likewise primarily composed of nitrogen (78%) and oxygen (21%) with trace concentrations of water vapor, carbon dioxide, and other gaseous molecules. Mars' is composed of 96% carbon dioxide, i.93% argon and 1.89% nitrogen forth with traces of oxygen and water. Contempo surveys accept besides noted trace amounts of marsh gas, with an estimated concentration of near 30 parts per billion (ppb).

Because of this, there is a considerable difference between the boilerplate surface temperature on Earth and Mars. On Earth, information technology is approximately 14°C, with plenty of variation due to geographical region, superlative, and time of year. The hottest temperature ever recorded on Earth was lxx.7°C (159°F) in the Lut Desert of Islamic republic of iran, while the coldest temperature was -89.ii°C (-129°F) at the Soviet Vostok Station on the Antarctic Plateau.

Space Shuttle Endeavor silhouetted against the atmosphere. The orange layer is the troposphere, the white layer is the stratosphere and the blue layer the mesosphere. Credit: NASA

Because of its thin atmosphere and its greater distance from the Sun, the surface temperature of Mars is much colder, averaging at -46 °C (-51 °F). Withal, because of its tilted axis and orbital eccentricity, Mars also experiences considerable variations in temperature. These tin can exist seen in the grade of a low temperature of -143 °C (-225.4 °F) during the wintertime at the poles, and a high of 35 °C (95 °F) during summer and midday at the equator.

The atmosphere of Mars is also quite dusty, containing particulates that measure out 1.5 micrometers in bore, which is what gives the Martian sky a tawny color when seen from the surface. The planet also experiences dust storms, which can turn into what resembles small tornadoes. Larger dust storms occur when the dust is blown into the atmosphere and heats upward from the Dominicus.

So basically, Earth has a dense temper that is rich in oxygen and water vapor, and which is more often than not warm and conducive to life. Mars, meanwhile, is mostly very cold, simply can become quite warm at times. It's also quite dry and very dusty.

Magnetic Fields:

When it comes to magnetic fields, Globe and Mars are in stark contrast to each other. On Earth, the dynamo effect created by the rotation of Globe's inner core, relative to the rotation of the planet, generates the currents which are presumed to exist the source of its magnetic field. The presence of this field is of extreme importance to both Earth's atmosphere and to life on Earth every bit we know it.

Map from the Mars Global Surveyor of the current magnetic fields on Mars. Credit: NASA/JPL

Essentially, World's magnetosphere serves to deflect most of the solar current of air'due south charged particles which would otherwise strip away the ozone layer and expose Earth to harmful radiation. The field ranges in forcefulness betwixt approximately 25,000 and 65,000 nanoteslas (nT), or 0.25–0.65 Gauss units (G).

Today, Mars has weak magnetic fields in various regions of the planet which appear to exist the remnant of a magnetosphere. These fields were commencement measured past the Mars Global Surveyor, which indicated fields of inconsistent strengths measuring at nigh 1500 nT (~sixteen-40 times less than World'due south). In the northern lowlands, deep touch on basins, and the Tharsis volcanic province, the field strength is very low. But in the ancient southern crust, which is undisturbed by giant impacts and volcanism, the field strength is higher.

This would seem to indicate that Mars had a magnetosphere in the past, and explanations vary as to how it lost it. Some propose that information technology was blown off, forth with the majority of Mars' atmosphere, by a large impact during the Tardily Heavy Bombardment. This impact, it is reasoned, would have as well upset the rut flow in Mars' fe core, arresting the dynamo outcome that would have produced the magnetic field.

Some other theory, based on NASA's MAVEN mission to written report the Martian temper, has it that Mars' lost its magnetosphere when the smaller planet cooled, causing its dynamo upshot to stop some iv.ii billion years agone. During the next several hundred one thousand thousand years, the Sun's powerful solar wind stripped particles away from the unprotected Martian atmosphere at a rate 100 to ane,000 times greater than that of today. This in turn is what acquired Mars to lose the liquid h2o that existed on its surface, as the environment to go increasing cold, desiccated, and inhospitable.

Satellites:

Earth and Mars are also similar in that both have satellites that orbit them. In Globe'southward case, this is none other than The Moon, our merely natural satellite and the source of the Earth's tides. It'due south existence has been known of since prehistoric times, and information technology has played a major role in the mythological and astronomical traditions of all human cultures. In addition, its size, mass and other characteristics are used as a reference betoken when assessing other satellites.

The Moon is one of the largest natural satellites in the Solar Arrangement and is the second-densest satellite of those whose moons who's densities are known (after Jupiter's satellite Io). Its diameter, at 3,474.8 km, is 1-4th the diameter of Earth; and at 7.3477 × 10²² kg, its mass is 1.two% of the Globe'southward mass. Information technology's mean density is 3.3464 g/cmⁱⁱⁱ , which is equivalent to roughly 0.6 that of Earth. All of this results in our Moon possessing gravity that is about 16.54% the strength of Globe'south (aka. 1.62 m/sⁱⁱ ).

The Moon varies in orbit around Earth, going from 362,600 km at perigee to 405,400 km at apogee. And similar nigh known satellites within our Solar Organisation, the Moon's sidereal rotation menstruum (27.32 days) is the same as its orbital period. This means that the Moon is tidally locked with Earth, with i side is constantly facing towards us while the other is facing abroad.

Thanks to examinations of Moon rocks that were brought back to Earth, the predominant theory states that the Moon was created roughly 4.v billion years ago from a collision between Globe and a Mars-sized object (known as Theia). This collision created a massive cloud of debris that began circling our planet, which eventually coalesced to grade the Moon we encounter today.

Mars has two small satellites, Phobos and Deimos. These moons were discovered in 1877 past the astronomer Asaph Hall and were named after mythological characters. In keeping with the tradition of deriving names from classical mythology, Phobos and Deimos are the sons of Ares – the Greek god of state of war that inspired the Roman god Mars. Phobos represents fear while Deimos stands for terror or dread.

Phobos measures about 22 km (14 mi) in diameter, and orbits Mars at a distance of ix,234.42 km when it is at periapsis (closest to Mars) and 9,517.58 km when it is at apoapsis (farthest). At this distance, Phobos is beneath synchronous altitude, which means that it takes only 7 hours to orbit Mars and is gradually getting closer to the planet. Scientists estimate that in 10 to l meg years, Phobos could crash into Mars' surface or break up into a band construction around the planet.

Meanwhile, Deimos measures virtually 12 km (vii.5 mi) and orbits the planet at a distance of 23,455.five km (periapsis) and 23,470.9 km (apoapsis). It has a longer orbital period, taking 1.26 days to consummate a full rotation effectually the planet. Mars may have boosted moons that are smaller than 50- 100 meters (160 to 330 ft) in diameter, and a grit ring is predicted betwixt Phobos and Deimos.

Scientists believe that these two satellites were one time asteroids that were captured by the planet's gravity. The low albedo and the carboncaceous chondrite composition of both moons – which is similar to asteroids – supports this theory, and Phobos' unstable orbit would seem to propose a recent capture. All the same, both moons have circular orbits almost the equator, which is unusual for captured bodies.

So while Earth has a single satellite that is quite large and dense, Mars has two satellites that are small and orbit it at a comparatively close altitude. And whereas the Moon was formed from Globe'due south ain debris after a rather severe standoff, Mars' satellites were likely captured asteroids.

Decision:

Okay, let's review. World and Mars have their share of similarities, but also some rather stark differences.

Mean Radius: 6,371 km                      three,396 km

Mass: 59.7×x²³ kg              half dozen.42 x 10²³ kg

Volume: 10.8 10 x¹¹ km³         1.63 x 10¹¹ km³

Semi-Major Axis: 0.983 – 1.015 AU      i.3814 – 1.666 AU

Air Pressure: 101.325 kPa                0.iv – 0.87 kPa

Gravity:9.8 m/southward²                     3.711 m/s²

Avg. Temperature: 14°C (57.2 °F)            -46 °C (-51 °F)

Temp. Variations:       ±160 °C (278°F)        ±178 °C (320°F)

Axial Tilt:                    23° 25.nineteen°

Length of Day: 24 hours                     24h 40m

Length of Year: 365.25 days                686.971 days

Water: Plentiful                      Intermittent (mostly frozen)

Polar Water ice Caps:         Yep                              Yep

In short, compared to Earth, Mars is a pretty small, dry, cold, and dusty planet. It has insufficiently depression gravity, very little temper and no breathable air. And the years are also mighty long, almost twice that of World, in fact. Even so, the planet does have its fair share of water (admitting mostly in ice form), has seasonal cycles like to Globe, temperature variations that are like, and a day that is nigh every bit long.

All of these factors will accept to exist addressed if e'er man beings desire to live there. And whereas some tin can be worked with, others volition have to be overcome or adjusted to. And for that, we will have to lean pretty heavily on our applied science (i.east. terraforming and geoengineering). All-time of luck to those who would like to venture there someday, and who do not programme on coming home!

We have written many articles about Mars hither on Universe Today. Here'southward an article almost how hard it will be to land large payloads onto the surface of Mars, and here's an article about the Mars methane mystery.

And here are some on the altitude between Earth and Mars, Mars' gravity, and if humans can live on Mars.

If y'all'd like more info on Mars, check out Hubblesite's News Releases about Mars, and here's a link to the NASA Mars Exploration home page.

And be sure to check out NASA'due south Solar System Exploration: Earth and Mars Comparing Nautical chart

We have recorded several podcasts just about Mars. Including Episode 52: Mars and Episode 92: Missions to Mars, Part 1.

Sources:

• NASA – All Near Mars
• NASA: Solar Arrangement Overview – Globe
• Academy of Phoenix – Mars Mission
• Wikipedia – Mars

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Source: https://www.universetoday.com/22603/mars-compared-to-earth/

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