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|Astronomy and Geology|
|Auster • History of Auster|
|Benthochordata • Thalassaflora|
Artistic depiction of Auster
|Adjective||Austerian, rarely Australian|
|Aphelion||98.5 million km |
61 million mi
|Perihelion||95.5 million km |
59 million mi
|Orbital period||209 days|
|Satellites||1 (asteroid Aethiopius)|
|Mean radius||1.47 Earths |
|Volume||3.18 Earths |
3.44 × 1012 km3
8.25 × 1011 mi3
|Mass||3.41 Earths |
2.04 × 1025 kg
|Mean density||5.93 g/cm3|
|Mean surface gravity||15.52 m/s2 |
|Sidereal rotation period||21 hours|
|Surface pressure||84.6 kPa|
1.5% carbon dioxide
0.3% water vapour
- See also: Terra Chordata § Auster
Auster, officially Epsilon Eridani e, is a super earth in the Epsilon Eridani system, the second planet from the star. It orbits at an average distance of 97 million km (60 million miles), in the "Goldilocks zone" of its stellar system. Epsilon Eridani is a K class star, commonly called an orange dwarf, and is considerably dimmer, smaller, and cooler than the sun. The oxygen concentration is about 15% in the atmosphere, and nitrogen makes up 83%. 1.5% is carbon dioxide, and the rest is composed of trace elements.
Auster can be broken up into similar compositional and physical layers to Earth, but due to pressure it lacks a fully liquid outer core, with a similar density to the its mantle. For this reason, its magnetic field is weaker, and animals have had to adapt to the slightly harsher radiation. Auster is far more tectonically active than Earth. Auster has one satellite, a 32 kilometer (20 mile) wide asteroid, caught in orbit 200 million years before Auster was terraformed. The satellite is named Aethiopius, after the land (Aethiopia) where Auster lived in Greco-Roman mythology.
Geography and TectonicsEdit
The ocean makes up about 80% of Auster's surface area, and thus it has more aquatic diversity than Earth. Almost no ice exists on Auster, even at the poles. The depth of the ocean reaches 50,000 feet, so overall Auster has much more water by volume than Earth. There are four oceans on Auster. The smallest of the three, the Thetis Ocean, is found between the continents in two branches; it lies in the tropics. The Eurus Ocean lies to the east of the main landmasses. The Zephyrus Ocean is the largest ocean on the planet, and lies to the west of the main landmasses. The Chronos Ocean lies over the north pole. It is like a capsule in time, with many otherwise extinct marine groups living in the area.
Compared to Earth, there is little land on Auster. As of 400 million years after terraforming (the time period used for the life forms) three continents exist, one stretching across most of the southern hemisphere, going over the south pole; and two smaller continents in the northern hemisphere. Even the tallest mountains rarely reach above 10,000 feet above sea level, and most land is swampy and low lying.
The southern continent, Panaustralia, stretches across 30% of the southern hemisphere, and makes up 50% of the planet's land. It is centered around 60°S. Panaustralia can be considered a supercontinent of sorts. The Thetis Ocean lies between Panaustralia and the northern continents. One of the northern continents, Hemitropica, lies around the equator, and is the smallest continent on the planet, making up only 20% of the planet's land. Despite its size, most of the land life of Auster lies on Hemitropica. The northernmost continent, Borealia, lies not far south of the North Pole, and makes up 30% of Auster's land. Borealia is the coldest of the three continents, but still averages 24°C.
The planet is in constant tectonic action, especially in the case of volcanism. Dozens of volcanic island chains exist in the middle of Auster's oceans at any given time. All known mass exinctions on the planet were caused due to volcanic activity, as it recovered easily from all other phenomena. It would likely be vulnerable to a gamma ray burst, but has not experienced one in its history. Auster experiences supercontinent cycles, in a shorter timescale than Earth, with supercontinents occurring about 200 million years apart. The next supercontinent on Auster will form about 50 million years from the time mentioned.
Since the introduction of Earthly life, four supervolcanoes have caused mass extinctions. The much higher tectonic activity (due to more heat in the interior of the planet) creates much more active volcanoes. Super Earths tend to quickly recover from other extinction events, such as asteroid impacts, so volcanoes are the only known cause of extinctions on the planet. A gamma ray burst would decimate nearly all life, due to the weak magnetic field, but in Auster's history no known gamma ray bursts have affected the planet. The first extinction occurred 60 million years after introduction; followed by one 170 million years hence; the Nyx Traps supervolcano, 277 million years hence, the worst in Austerian history; and a relatively mild extinction 330 million years hence.
Before the time of terraforming, almost no oxygen existed on Auster. Due to the green algae and cyanobacteria (but not plants) introduced, the oxygen levels rose to 15% within 400 million years, and are still rising. The large proportion (1.5%) of carbon dioxide in the atmosphere, as least compared to Earth, is because of the high amounts of volcanic activity on Auster. This is the reason for Auster's tropical climate, considering that it is proportionally closer to its star than Earth is to the sun. Like Earth, nitrogen levels are high, at 83%; once again, a lot of this nitrogen is due to volcanic activity. Other gasses in the atmosphere include water vapour (0.3%), argon (0.15%), neon (0.002%), and helium (0.001%). Interestingly, despite the higher temperatures, there is less water vapour than on Earth, possibly for the reason that Auster does not a have a complete water cycle, with a near constant temperature.
Like Earth, Auster has layers in its atmosphere, including a troposphere, stratosphere (including an ozone layer), mesosphere, thermosphere, and exosphere. Its thermosphere is home to extravagant displays of auroras, as the charged particle concentration hitting Auster is considerably higher than on Earth. Because of the weak magnetic field, auroras extend considerably farther south than they would on Earth.
Weather and ClimateEdit
The climate of Auster is tropical, similar to that of the Amazon rainforest, as the carbon dioxide content of the atmosphere is 1.5%; on Earth the carbon dioxide level is only 0.039%. The average temperature on Auster is 29ºC; at the equator reaching 36ºC. These conditions benefit the introduced life on Auster. Ice caps are nonexistent on Auster due to the high temperatures.
Weather on Auster includes rainfall, wind, and many hurricanes due to the warm temperatures, but snowfall is nearly absent from the planet, as the temperature of Auster is too warm to allow water to freeze. Tropical storms are so strong as sometimes to completely remake shorelines. Wind can reach speeds of up to 330 kph during hurricanes, and this would devastate any plants on the surface. However, no plants were introduced, and instead cyanobacteria and green algae produce oxygen, as well as form the basis for most food chains.
Auster is heavily bombarded with radiation, for two reasons. First, the outer core is not completely liquid, making for a weaker magnetic field. Second, Epsilon Eridani is a young star, so gives off more radiation than the sun. Because of the radiation and the age of the planet, life never developed on Auster. However, its habitability was enough so that terraforming was quite effective, resulting in millions of species derived from those on Earth.
The crust of Auster is very similar to that of Earth, with oxygen and silicon as the primary elements. Unlike Earth, aluminum is rarer in the crust, and magnesium is more abundant. Iron also exists in larger quantities in the crust than on Earth. Calcium, sodium, and potassium are also abundant in the crust, but in lower quantities than the aforementioned elements. Like on Earth, the most abundant compound in the crust is silica (SiO2). Evidently, Auster has more oceanic crust than does Earth.
In the mantle of Auster, only one layer exists, due to the abundant interior heat within Auster. It is similar in consistency to Earth's asthenosphere, and a rigid mesosphere is nonexistent. Oxygen and magnesium are in the largest quantities, followed by silicon. Like on Auster's crust, iron is more abundant than Earth, while aluminum is rarer. Metal oxides are the most common compounds in Auster's mantle. One force causing increased plate tectonics is the fact that convection occurs not only in the upper layers of the mantle, but in the lower layers too. A hotter internal temperature inhibits a rigid layer of the mantle.
Auster's core does have two layers, but the distinction is less than that of Earth. So much pressure exists in the center of Auster that the outer core generates a magnetic field only 65% as strong as Earth. Of course, the magnetic field is strong enough to allow life to survive, but any humans on the planet would suffer genetic damage due to the radiation. 90% of Auster's core is iron, and nickel exists in the core, but surprisingly magnesium is somewhat abundant in the core, as it is in the rest of the planet. The inner core is completely solid, just as on Earth, and the outer core is liquid, but very viscous compared to Earth's outer core.
Orbit and RotationEdit
Auster orbits right in the middle of Epsilon Eridani's habitable zone, at an average distance of 97 million km. This is somewhat variable, from 98.5 million km at its perihelion, to 95.5 million km at its aphelion. One day on Auster is 21 hours, shorter than Earth's day. This is due to a trend that larger planets have shorter days, although this has exceptions, for example, Venus rotates in 243 Earth days, while Mars rotates in just over one Earth day. Still, these exceptions are always due to an unusually long rotational period, which Venus obviously bears; its orbit, at 224 days, is shorter than its rotational period, at 243 days. Auster's orbit is not very elliptical, comparable in eccentricity to Earth.
Auster has an axial tilt of only 10.5º, and so experiences minimal differences in seasons. However, Auster experiences precession, which due to a lack of a stabilizing moon can vary from 5º to 17º. Still, this is not enough to damage any life living on Auster. The precession happens very slowly compared to Earth, in cycles of five million years.
For several reasons, native life on Auster does not exist. For one, the stellar radiation possibly sterilized the planet, or prevented life from existing in the first place. Earth's life was evidently more adaptable, so when the planet was terraformed all sorts of new creatures evolved. From only seven introduced animals came perhaps millions of animal species on the planet. Another reason Auster lacks native life is that it lacks almost all organic material, with Carbon being one of the rarest elements in its crust. Despite all of the radiation, oceans remained existent on Auster, unlike the fate of Mars, which was stripped of most surface water when its magnetic field was destroyed.
When Auster was terraformed, it was at the stage in its development when life was likely to evolve when it hadn't before, but with the introduction of many Earthly bacteria, these primitive organisms, if they ever existed, didn't stand a chance against the relatively advanced (compared to an original life form) bacteria and archaea. The diatoms introduced were far ahead of even the bacteria, being eukaryotes, and of course did well in the ecosystems of Auster. In conclusion, the introduction of life to Auster may have inhibited life from ever evolving on the planet.
Three asteroid belts exist in the Epsilon Eridani system, one between Auster and the Epsilon Eridani b, analogous the one between Mars and Jupiter, one between the Epsilon Eridani b and d, and one outside of the Epsilon Eridani d, analogous to the Kuiper belt. Epsilon Eridani b ended up moving inwards not long after the formation of the system, and eventually knocked asteroids from both the inner and middle belts out of place. Similarly to the Late Heavy Bombardment, both Auster and Epsilon Eridani c were bombarded by asteroids. One large asteroid, around 32 kilometers wide, was caught in Auster's orbit during this period, giving Auster its only satellite, Aethiopius.
Despite the fact that Aethiopius is a moon, it does not serve a purpose similar to that of Earth's moon due to its size. Unlike some scientists suspect, the lack of a large moon does not cause large climatic swings due to extreme axial tilt on Auster, although this might be due to the fact that a larger terrestrial planet would have more stability in general. As mentioned above, the low average axial tilt means that even with a greater precession than Earth, the seasons do not wildly vary.