Description of Litoria

Introduction

• Litoria is a terrestrial planet, the second planet from its primary, and the second-largest of the three planets in its solar system. At .738 Earth masses, it is slightly smaller than the planet Venus. It is the only planet in its solar system within the habitable zone and thus capable of sustaining life.

• The inner planet of the system is a small lifeless planet not unlike Mercury. The outer planet is a large gas giant like Jupiter.

• Physical characteristics:
  • mean radius 4,778.25 km
  • mean circumference 30,023.66 km
  • flattening .0024887
  • surface area 29,081,890 km2
    • land 17,158,315 km2 (59%)
    • water 11,923,574 km2 (41%)
  • volume 456,674,562,012 km3
  • mass
  • escape velocity 8.2 km/s
  • sidereal rotation period 0d 25h 0m 38.2s
  • axial tilt 11.250989°
  • surface temperature
    • minimum -85.4°C
    • mean -12.0°C
    • maximum 60.2°C
  • surface pressure 90.2 kPa
  • atmosphere composition
    • nitrogen 76%
    • oxygen 22%
    • argon 0.9%
    • carbon dioxide 0.1%
    • water vapor 1.0%

• Orbital characteristics:
  • aphelion 147,280,599.28 km
  • perihelion 143,098,003.47 km
  • semi-major axis 145,189,301.38 km
  • eccentricity 0.0072
  • orbital period 360.001 days
  • mean orbital speed
  • inclination 1.2° to sun’s equator

• The planet was formed 3.5 billion years ago, and life appeared on its surface within a billion years. Since then, Litoria's biosphere has significantly altered the atmosphere and other abiotic conditions on the planet, enabling the proliferation of aerobic microorganisms as well as the formation of an ozone layer which, together with Litoria’s magnetic field, blocks harmful radiation, permitting life on land. The physical properties of Litoria, as well as its geological history and orbit, have allowed life to persist during this period. Litoria is expected to continue supporting life for another 1.5 billion years, after which the rising luminosity of its sun will eliminate the biosphere.

• Litoria's outer surface is divided into several rigid segments, or tectonic plates, that gradually migrate across the surface over periods of many millions of years. About 41% of the surface is covered with a salt-water ocean, the remainder consisting of one supercontinent and a few scattered islands. Litoria's interior remains active, with a thick layer of relatively solid mantle, a liquid outer core that generates a magnetic field, and a solid iron inner core.

Chronology

• The earliest dated solar system material is dated to 3.5529 ± 0.0006 billion years ago, and by 3.54 billion years ago Litoria and its two companion planets in the solar system formed out of the solar nebula, a disk-shaped mass of dust and gas left over from the formation of the sun. This assembly of Litoria through accretion was largely completed within 10–20 million years. Initially molten, the outer layer of Litoria cooled to form a solid crust when water began accumulating in the atmosphere. The moons formed shortly thereafter, 2.96 billion years ago.

• Litoria's two natural satellites provide ocean tides, stabilize the axial tilt and gradually slow the planet's rotation. Obviously, the larger moon exerts more of a force than the smaller. The moons were formed as a result of a large object with about 10% of Litoria's mass impacting Litoria in a glancing blow. Some of this object's mass would have merged with Litoria and a portion would have been ejected into space, but enough material would have been sent into orbit to form the larger nearer moon and the smaller farther moon.

• Outgassing and volcanic activity produced the primordial atmosphere. Condensing water vapor, augmented by ice and liquid water delivered by asteroids and the larger proto-planets and comets produced the oceans. The newly-formed sun was only 70% of its present luminosity, but a combination of greenhouse gasses and higher levels of solar activity served to raise Litoria's surface temperature, preventing the ocean from freezing over.

• There was a rapid initial growth of the continental crust followed by a long-term steady continental area. Over several hundreds of millions of years, the surface continually reshaped as continents formed and broke up. The continents migrated across the surface, occasionally combining to form a supercontinent. The present supercontinent recombined roughly 300–250 million years ago.

Evolution of life

• Highly energetic chemistry produced a self-replicating molecule around 3.3 billion years ago, and 0.5 billion years later the last common ancestor of all life existed. The development of photosynthesis allowed the sun's energy to be harvested directly by life forms; the resultant oxygen accumulated in the atmosphere and formed in a layer of ozone in the upper atmosphere. The incorporation of smaller cells within larger ones resulted in the develoopment of complex cells called eukaryotes. True multicellular organisms formed as cells within colonies became increasingly specialized. Aided by the absorption of harmful ultraviolet radiation by the ozone layer, life colonized the surface of Litoria. Evolution has followed a path similar to that on planet Earth up until the only mass extinction recorded in the geology of the planet. The cause of the extinction is not yet known, but it occurred before the evolution of mammals and eliminated the large dinosaurs and reptiles. Life on Litoria today consists of all the familiar terrestrial animal classes with the exception of Mammalia.
• The present pattern of ice ages began about 50 million years ago. The polar regions have since undergone repeated cycles of glaciation and thaw, repeating approximately every 100,000 years. The last ice age ended 20,000 years ago.

Composition and structure

• Litoria is a terrestrial planet, meaning that it is a rocky body. It is the larger of the two terrestrial planets in size and mass. Of these two planets, Litoria also has the highest density, the highestsurface gravity, the strongest magnetic field, and the fastest rotation. It is also the only planet with active plate tectonics.

Shape

• The shape of Litoria is very close to that of an oblate spheroid, a sphere squished along the orientation from pole to pole such that there is a bulge around the equator. This bulge results from the rotation of Litoria, and causes the diameter at the equator to be 68 km longer than the pole to pole diameter. The average diameter of the reference spheroid is about 9,556.5 km.

Chemical composition

• The mass of Litoria is approximately 5.98 × 1024 kg. It is composed mostly of iron (33.3%), oxygen (30.1%), silicon (14.2%), magnesium (14.1%), sulfur (2.6%), nickel (1.5%), calcium (1.3%), and aluminum (1.8%); with the remaining 1.1% consisting of trace amounts of other elements. Due to mass segregation, the core region is composed of iron (91.8%), with smaller amounts of nickel (4.8%), sulfur (3.3%), and 1% trace elements.

Internal structure

• The interior of Litoria is divided into layers by their chemical or physical properties. The outer layer of Litoria is a chemically distinct silicate solid crust, which is underlain by a highly viscous solid mantle. The crust is separated from the mantle by a thin layer. The thickness of the crust varies, averaging 6 km under the oceans and 30–50 km on the continents. The crust and the cold, rigid, top of the upper mantle are collectively known as the lithosphere, and it is of the lithosphere that the tectonic plates are comprised. Beneath the lithosphere is the asthenosphere, a relatively low-viscosity layer on which the lithosphere rides. Important changes in crystal structure within the mantle occur at 410 and 660 kilometers below the surface, spanning a transition zone that separates the upper and lower mantle. Beneath the mantle, an extremely low viscosity liquid outer core lies above a solid inner core. The inner core rotates at a slightly higher angular velocity than the remainder of the planet, advancing by 0.1–0.5° per year.

Heat

• Litoria's internal heat comes from a combination of residual heat from planetary accretion (about 20%) and heat produced through radioactive decay (80%). The major heat-producing isotopes in Litoria are potassium-40, uranium-238, uranium-235, and thorium-232. At the center of the planet, the temperature may be up to 7,000 K and the pressure could reach 360 GPa. Because much of the heat is provided by radioactive decay, scientists believe that early in Litoria history, before isotopes with short half-lives had been depleted, Litoria's heat production would have been much higher. This extra heat production, twice present-day at approximately 3 billion years ago,[63] would have increased temperature gradients within Litoria, increasing the rates of mantle convection and plate tectonics, and allowing the production of igneous rocks such as komatiites that are not formed today.

• Total heat loss from Litoria is 5.1 × 1013 watts. A portion of the core's thermal energy is transported toward the crust by mantle plumes, a form of convection consisting of upwellings of higher-temperature rock. These plumes can produce hotspots and flood basalts. More of the heat in Litoria is lost through plate tectonics, by mantle upwelling associated with mid-ocean ridges. The final major mode of heat loss is through conduction through the lithosphere, the majority of which occurs in the oceans because the crust there is much thinner than that of the continents.

Tectonic plates

• The mechanically rigid outer layer of Litoria, the lithosphere, is broken into pieces called tectonic plates. These plates are rigid segments that move in relation to one another at one of three types of plate boundaries, convergent boundaries, at which two plates come together; divergent boundaries, at which two plates are pulled apart; and transform boundaries, in which two plates slide past one another laterally. Earthquakes, volcanic activity, mountain building, and oceanic trench formation can occur along these plate boundaries. The tectonic plates ride on top of the asthenosphere, the solid but less viscous part of the upper mantle that can flow and move along with the plates, and their motion is strongly coupled with patterns convection inside Litoria’s mantle.

• As the tectonic plates migrate across the planet, the ocean floor is subducted under the leading edges of the plates at convergent boundaries. At the same time, the upwelling of mantle material at divergent boundaries creates midocean ridges. The combination of these processes continually recycles the oceanic crust back into the mantle. Because of this recycling, most of the ocean floor is less than 100 million years in age.

Surface

• Litoria's terrain varies greatly from place to place. About 45% of the surface is covered by water, with much of the continental shelf below sea level. The submerged surface has mountainous features, including a mid-ocean ridge system, as well as undersea volcanoes, oceanic trenches, submarine canyons, oceanic plateaus and abyssal plains. The remaining 55% not covered by water consists of two coastal plains and foothills, two pole-to-pole mountain chains, a large inland desert and two polar icecaps, both of which are over land.

• The elevation of the land surface of Litoria varies from the low point of −? m at the desert sea, to an altitude of 14,967 m at the top of the western mountain chain.

Hydrosphere

• Litoria's hydrosphere consists chiefly of the single ocean, but technically includes all water surfaces on the planet, including the polar ice caps, several lakes, many rivers, and underground waters down to a depth of 2,000 m. The deepest underwater location is the mid-oceanic ridge with a depth of −9,334.2 m. The average depth of the ocean is 2,700 m. About 94% of the water is saline, while the remaining 6% is fresh water. Most of the fresh water, about 74.7%, is currently ice. Sea water has an important influence on the planet's climate, with the ocean acting as a large hear reservoir.

Atmosphere

• The height of the troposphere varies with latitude, ranging between 9 km at the poles to 18.5 km at the equator, with some variation due to weather and seasonal factors.

• Litoria's biosphere has significantly altered its atmosphere. Oxygenic photosynthesis evolved 2.4 billion years ago, forming the primarily nitrogen-oxygen atmosphere of today. This change enabled the proliferation of aerobic organisms as well as the formation of the ozone layer which, together with Litoria's magnetic field, blocks ultraviolet solar radiation, permitting life on land. Other atmospheric functions important to life on Litoria include transporting water vapor, providing useful gases, causing small meteors to burn up before they strike the surface, and moderating temperature. This last phenomenon is known as the greenhouse effect. Trace molecules within the atmosphere serve to capture thermal energy emitted from the ground, thereby raising the average temperature. Carbon dioxide, water vapor, methane and ozone are the primary greenhouse gases in Litoria's atmosphere.

Weather and climate

• Litoria's atmosphere has no definite boundary, slowly becoming thinner and fading into outer space. Three-quarters of the atmosphere's mass is contained within the first 13 km of the planet's surface. This lowest layer is called the troposphere. Energy from the sun heats this layer, and the surface below, causing expansion of the air. This lower density air then rises, and is replaced by cooler, higher density air. The result is atmospheric circulation that drives the weather and climate through redistribution of heat energy.

• The primary atmospheric circulation bands consist of the trade winds in the equatorial region below 30° latitude and the westerlies in the mid-latitudes between 30° and 60°. Ocean currents are also important factors in determining climate, particularly the thermohaline circulation that distributes heat energy from the equatorial oceans to the polar regions.

• Water vapor generated through surface evaporation is transported by circulatory patterns in the atmosphere. When atmospheric conditions permit an uplift of warm, humid air, this water condenses and settles to the surface as precipitation. Most of the water is then transported to lower elevations by river systems and usually returned to the oceans or deposited into lakes. Atmospheric circulation, topological features and temperature differences determine the average precipitation that falls in each region.

Litoria can be subdivided into specific latitudinal belts of approximately homogeneous climate. Ranging from the equator to the polar regions, these are the tropical, subtropical, temperate, and polar climates.

Magnetic field

• Litoria’s magnetic field is shaped roughly as a magnetic dipole, with the poles currently located proximate to the planet's geographic poles. According to the dynamo theory, the field is generated within the molten outer core region where heat creates convection motions of conducting materials, generating electric currents. These in turn produce Litoria's magnetic field. The convection movements in the core are chaotic, and periodically change alignment. This results in field reversals at irregular intervals averaging a few times every million years. The most recent reversal occurred approximately 740,000 years ago. The field forms the magnetosphere, which deflects particles in the solar wind.

Orbit and rotation

Rotation

• Apart from meteors within the atmosphere, the main apparent motion of celestial bodies in Litoria's sky is to the west at a rate of 15°/h = 15'/min. This is equivalent to an apparent diameter of the Sun or Moon every two minutes; the apparent sizes of the Sun and the Moon are approximately the same.

Orbit

• Viewed from the celestial north pole, the motion of Litoria, the moon and their axial rotations are all counter-clockwise. Viewed from a vantage point above the north poles of both the sun and Litoria, Litoria appears to revolve in a counterclockwise direction about the sun.

• The Hill sphere, or gravitational sphere of influences (the maximum distance at which Litoria's gravitational influence is stronger than the more distant Sun and planets) of Litoria is about 1,000,000 km in radius. Objects must orbit Litoria within this radius, or they can become unbound by the gravitational perturbation of the sun.

Axial tilt and seasons

• Because of the small axial tilt of Litoria, the amount of sunlight reaching any given point on the surface varies over the course of the year. This results in a slight seasonal change in climate, with summer in the northern hemisphere occurring when the north pole is pointing toward the sun, and winter taking place when the pole is pointed away. During the summer, the day lasts longer and the sun climbs higher in the sky. In winter, the climate becomes generally cooler and the days shorter. Above the Arctic Circle, an extreme case is reached where there is no daylight at all for part of the year, a polar night. In the southern hemisphere the situation is exactly reversed, with the south pole oriented opposite the direction of the north pole.

• By astronomical convention, the four seasons are determined by the solstices, the point in the orbit of maximum axial tilt toward or away from the sun—and the equinoxes, when the direction of the tilt and the direction to the Sun are perpendicular. The winter solstice occurs on about ______, the summer solstice ______, the spring equinox ______, and the autumnal equinox ______.

• The changing Litoria-sun distance results in an increase of about ___% in solar energy reaching Litoria at perihelion relative to aphelion. Since the southern hemisphere is tilted toward the Sun at about the same time that Litoria reaches the closest approach to the Sun, the southern hemisphere receives slightly more energy from the Sun than does the northern over the course of a year. However, this effect is much less significant than the total energy change due to the axial tilt, and most of the excess energy is absorbed by the higher proportion of water in the southern hemisphere.

Moons

• The inner moon is a relatively large, terrestrial, planet-like satellite, with a diameter about one-quarter of Litoria's. The gravitational attraction between Litoria and the inner moon causes tides on Litoria. The same effect on the moon has led to its tidal locking, i.e., its rotation period is the same as the time it takes to orbit Litoria. As a result, it always presents the same face to the planet. As the moon orbits Litoria, different parts of its face are illuminated by the sun, leading to the lunar phases; the dark part of the face is separated from the light part by the solar terminator. Because of their tidal interaction, the moon recedes from Litoria at the rate of approximately __ mm a year.

• Viewed from Litoria, the moon is just far enough away to have very nearly the same apparent-sized disk as the Sun. The angular size of the moon is slightly smaller than that of the sun. This means that total eclipses cannot occur. However, the annular eclipses are spectacular.

• The most widely accepted theory of the moons’ origin states that they were formed from the collision of a large body with the early Litoria. The inner moon resulted from a large chunk that remained close to the planet. The outer moon is a smaller chunk that was captured by the planet’s gravitational pull at a farther distance.

Inner Moon

• Physical characteristics:
  • mean radius 1,911.3 km (0.4 “earths”)
  • flattening .00128
  • surface area 45,882,530 km2
  • volume 29,231,759,981.8 km3
  • mass
  • sidereal rotation period synchronous
  • axial tilt 5.125° (to orbit plane)

• Orbital characteristics:
  • semi-major axis 681,828 km
  • eccentricity 0.009
  • orbital period 30.01 days
  • inclination .051° to the ecliptic

Outer Moon

• Physical characteristics:
  • mean radius 101.5 km
  • flattening .000887
  • surface area 129,396.26 km2
  • volume 4,377,906.797 km3
  • mass
  • sidereal rotation period synchronous
  • axial tilt 24.25°

• Orbital characteristics:
  • semi-major axis 1,209,310.38 km
  • eccentricity 0.01503
  • orbital period 20.001 days
  • inclination 0.75° to the ecliptic

Habitability

• A planet that can sustain life is termed habitable, even if life did not originate there. Litoria provides the requisite conditions of liquid water, an environment where complex organic molecules can assemble and sufficient energy to sustain metabolism. The distance of Litoria from the sun, as well as its orbital eccentricity, rate of rotation, axial tilt, geological history, sustaining atmosphere and protective magnetic field all contribute to the conditions necessary to originate and sustain life on this planet.

Biosphere

• The planet's life forms are sometimes said to form a "biosphere". This biosphere is generally believed to have begun evolving about 2.5 billion years ago. The biosphere is divided into a number of biomes, inhabited by broadly similar plants and animals. On land primarily latitude and height above sea level separates biomes. Biomes lying within the Arctic Circle, Antarctic Circle or in high altitudes are relatively barren of plant and animal life, while the greatest latitudinal diversity of species is found at the equator. With respect to biomes, the two shores of Litoria are mirror images of each other.