Gaea (better than Earth)

I think I could do better than nature.

***Composition of Gaea***

I'm gonna lower the density a smidge to decrease the surface gravity, by increasing the amount of radioactive elements in the mantle (slightly raising density, and raising the internal temperature and thus power of the magnetic field), decrease the size of the iron core (drastically decreasing density and the power of the magnetic field). The idea is that we keep the same magnetic properties of the Earth while decreasing the surface gravity. (More radioactive materials is also good for power plants)

***Surface of Gaea***

I'm also going to shrink the Earth, but only around the oceans, keeping the shape of the continents more or less the same, but folding them around more of the planet. We'll go from 70% ocean to 40% ocean surface, and we'll expand the absolute land area slightly as well. This isn't necessarily the best for biodiversity in the ocean, but we're not ocean creatures! In fact we can increase the amount of ocean life by reducing the amount of water. Shallower water overall reduces the amount of deep ocean that doesn't support complex life. This is because for life to get a hold, you need an energy source and a nutrient/mineral/solid source. Energy can either be sunlight or volcanic vents. Volcanic vents are small and localized, and don't support large food chains. Sunlight can't reach too far underwater. Nutrients have to come from the sea floor. So if there's lots of sunlight at the surface of the water but the nutrients are at the bottom, it's really like you only have one of them. Shallower water results in sunlight getting all the way down to the nutrients. So shallower, smaller oceans.

What I've done is shrink the earth down and make it less dense, both of which decrease its surface gravity significantly. This makes putting rockets in space a lot easier! (Although for normal rockets the next step makes it harder for them to function, other launch vehicle designs exist which can compensate--and even so there should still be a net gain.)

***Atmosphere of Gaea***

The next step is the change the atmosphere of the Earth. We're increasing its pressure at the surface from 1 atmosphere to 5. Most of this will be in the form of mostly inert nitrogen, but we'll also slightly increase the partial pressure of oxygen--better gas mileage :) and bigger bugs :(. This new atmosphere more evenly distributes humidity and temperature, resulting in a more uniformly temperate world.

Oh and did I mention that humans can fly now? That's right, strap on a wing suit or have been born with genetically modified wings and you can flap your way into the skies! The lower gravity and the higher atmospheric pressure have afforded this--and despite how much I love space flight *this* is the main reason I have lowered the gravity.

The atmosphere would seem much closer to sunset all the time, due to the thicker atmosphere and the oranger sun. At noon it would still be mostly blue with a white near-horizon sky, but later or earlier the horizon will appear orange, and the sun and its light will take on an orange hue as well. As the sun sets, it will turn shades of deep red before disappearing just above the horizon. The numerous bright moons, combined with the thicker atmosphere, and lack of major deserts, make deep sky astronomy on Gaea quite difficult. Water boils at 151.9^o C, 205.4^o F, and 425^o K. If we redefine the Celsius scale based upon the new boiling point of water, its degrees are now small enough to compete with Fahrenheit, thus removing the one thing it had going for it.

***Biology, Climate, and Geology of Gaea***

The thicker atmosphere results in the ability for larger animals to fly, and the increased oxygen partial pressure results in larger bugs. The first new animals to evolve flight will likely be species that already glide, like flying squirrels. Birds can grow larger and support larger brains, (in fact every animal can support larger brains). Land animals can grow larger and taller in the lower gravity. The result of this is that we could expect, over enough time, even more diversity in the sapient species of Gaea. Elephants, Parrots, Ravens, and more may begin a civilized existence. I'd also like to bring back some extinct species to this world. Dinosaurs can live on Australia (although Australians might argue that putting them on the moon Antikithon would be better) because if you're going to resurrect the only sorts of creatures which could really fuck humans up, you'd better do it far away from anything else! We'll also bring back the very long-lasted Homo erectus, and some other human and Australopithecus species. Homo sapiens sapiens might screw things up--but if I did add them I would be sure to have it both in the form of technological civilization *and* tribal hunter gatherers. The civilization would have to be careful about preservation of the natural life, or else the Energy Orb of Stop Doing That, in low orbit around Gaea, will smite them :P.

The more evenly temperate and humid atmosphere results in a lack of large deserts. There are dry zones and wet zones, but they're not as dry and wet as before. Much more of the world is a temperate forest, deserts become savannas, and the arctic and antarctic are warmer.

The lower gravity of Gaea results in taller mountains as well, and the greater internal heat would result in greater volcanism. Atmospheric pressure remains high even at the top of Mount Everest, and because the scale height of the atmosphere is taller, the air is still breathable.

But the planet Gaea is not where the improvements end!

***Gaea's Sun: Helios***

* Spectral type: K1 V (Orange Dwarf star. Produces a slightly yellower light, but much less UV. It will also last 2 times longer than the Sun.)
* Temperature: 4960 Kelvins
* Mass: 0.8 Solar Masses
* Radius: 0.98 Solar Radii
* Luminosity: 0.524 Solar Luminosities
* Earth-Insolation Radius: 0.72387 au (Where the Earth would have to orbit to get the same heat and light)

***Physical Characteristics of Gaea***

* Rotation Period: 24.0 hours
* Density: 4.9 g/cm^3
* Surface Gravity: 7.416 m/s^2 (0.756 G)
* Radius: 5415 kilometers (0.85 Earth radii)
* Mass: 3.261 * 10^24 kg (0.546 Earth Masses)
* Atmosphere: 5 atmospheres
* Albedo: 0.34
* Semi Major Axis: 0.7016 au
* Eccentricity: ~0
* Inclination: 0 (By definition)
* Roche Limit: 11,728 km (for a satellite with density of 3.5 g/cm^3, min distance a satellite can orbit)
* Geosyncronous Altitude: 34,525.0988 km (possibly unstable due to Selene!)
* Hill Sphere: 924,451 km (2.401 Lunar Distances, max distance a satellite can orbit)
* Orbital Period: 240 days (This is the synodic period--makes the calendar much simpler. I can't be bothered to recall how to calculate the sidereal period so just imagine the star's mass is different to account for the slight difference. 240 has 20 factors, which makes math quite nice with this number.)
* Helios Angular Diameter: 0.74 degrees. (1.397 * Sun from Earth)

***Moons of Gaea***

The Moon is nice and all, but we can do better! Let's sack the large, distant moon and get ourselves three smaller ones and one even larger one.

**Hecate**

* *The smallest moon of Gaea, a tiny asteroid reminiscent of Phobos*
* Density: 3.8 g/cm^3
* Dimensions: 43 km * 23 km * 19 km
* Inclination: 5 degrees from equatorial plane.
* Semi Major Axis: 14,234 km
* Sidereal Orbital Period: 6.35 hours
* Synodic Orbital Period: 8.6347 hours

**Selene**

* *Covered in craters and the distinctive maria of the original Moon. It is just big enough in the sky to block out the Sun--but since it is roughly 25 degrees tilted from the ecliptic instead of 5 degrees, eclipses are less common.*
* Inclination: 7 degrees from equatorial plane.
* Semi Major Axis: 38,440 km (0.1 Lunar Distances)
* Sidereal Orbital Period: 28.196 hours
* Synodic Orbital Period: 6.72 days (Selene orbits so close to geosyncronous orbit that it takes a long time to drift across the sky, because it's chasing the surface of the planet.)
* Radius: 243 km (0.14 Lunar Radii, ~1/2 Ceres radii.)
* Albedo: 0.07 (very dark.)

**Artemis**

* *Artemis is a medium-sized moon with hints of recent volcanism.*
* Inclination: 27 degrees from the equator, 4 degrees from the ecliptic.
* Semi Major Axis: 136,000 (0.3533 Lunar Distances)
* Mass: 0.034 Lunar Masses.
* Radius: 590.58 km (0.34 Lunar Radii.)
* Density: 2.9 g/cm^3.
* Gravity: 0.03 G
* Orbital Period: 7.8182 days

**Antikithon**

* *Named for the hypothetical Counter-Earth of Greek philosophy (Antichthon), but this counter-earth has a more easily pronounceable name and is "counter" the barycenter, not the Sun or some "Central Fire." It has habitable conditions similar to Earth's, but it is cooler and is covered in ice and water with very little land. Its high axial tilt gives it a colder equator than its poles, while the polar and middle-latitude regions go between very hot and very cold. This regulates its temperature over time, keeping it from freezing solid. Technically, Antikithon is a binary planet, not a moon.*
* Mass: 0.25 Earth masses.
* Gravity: 0.46 G.
* Ocean/Ice average: 92% of surface.
* Density: 3.4 g/cm^3
* Radius: 4714.54 (0.74 Earth radii)
* Rotation Period: 8 hours (This will give it a visibly squashed appearance and an equatorial bulge.)
* Axial Tilt (from sun-centric orbital plane): 72 degrees
* Albedo: 0.55
* Atmosphere: 0.32 Atmospheres. (60% N2, 40% O2)
* Inclination: 3 degrees from the ecliptic.
* Semi Major Axis: 731,070 km (1.899 Lunar Distances)
* Orbital Period: 80.0 days (Again, I have fudged this value because I can't figure out the synodic period here... the semi major axis should be a little higher or lower to generate a synodic period of a nice round 80 days. This value is the sidereal period.)
* Subsatellite Moons: three little asteroids of its own.

***Other Planets of the Heliosian System***

* Hephaestus: 0.098 au sma, 1400 km radius.
* Hermes: 0.21 au sma, 5320 km radius. Thin, hot atmosphere.
* Aphrodite: 0.62 au sma, 6829 km radius. 1.4 atmospheres, warm but habitable temperatures. Almost bone-dry.
* Gaea: See above.
* Ares: 1.1 au sma, 4030 km radius. 0.08 atmospheres, cool. Rusted red. Significant amounts of ice, sparse lakes near the equator. 9 asteroid moons and a ring.
* Zeus and Hera: 5.6 au sma, Binary gas giant planets. 0.6 and 0.3 Jupiter masses. 1 lunar distance apart. Several barycentric moons.
* Khronos: 12 au sma, 0.6 Jupiter masses. 60 moons.
* Poseidon: 18 au sma, 0.08 Jupiter masses. 27 moons.
* Hades: 23 au sma (3/2 resonance with Poseidon), 829 km radius. 3 atmospheres of pressure.
* Octal Dwarfs: 72 au sma, A binary orbiting a binary, which is itself orbiting a binary orbiting a binary. (Each binary is two dwarf planets)