Understanding the Equation Variables
N - The number of possible ascension species currently residing in our Milky Way galaxy.
Gs - The population of stars in our galaxy. Not definitively known but widely thought to be about 300 billion stars.
Cls - Civilization's lifespan from the development of radio. An unknown value as we are the only ascension species that we know of. The development of radio is the minimum level of technology needed for communication and to be defined as an "ascension species". It is widely believed that intelligent life dies off rather quickly either the result of...
Death by their technology, or,
Altering their planet's environment making it unlivable.
Snp - Number of planets per star (our solar system has eight). Unknown but some think that our solar system might be higher than average.
Gg - Solar systems having outer gas giants. Value unknown.
Gas giants in an outer solar system are thought to be needed to clear out comets from its inner solar system that would otherwise cause a high rate of long-term catastrophic evolution damaging impacts.
Gas giants are also thought to allow the mass deposit of planetary water in the inner solar system by asteroids thus creating oceans.
Sfgk - Stars of spectral classes F, G and K (our sun is a Class G star). A known value. These are stars with long, stable, suitable length lifetimes that emit lower amounts of life-damaging UV radiation.
Snb - Stars that are non-binary (or single-star solar systems). A known value. Binary stars make a stable planetary environment very unlikely. Most stars are binaries.
Sghz - Stars located in the Galactic Habitable Zone. A calculated value. These are stars located outside of our galaxy's dense chaotic core and its ~200 dense globular clusters. These two galactic areas do not contain the long-term stable environment that's needed for the development of complex life. The Galactic Habitable Zone comprises a minority of our galaxy's stars.
Sp - Stars with planets. An estimated value based on exoplanet studies. Only planets or possibly very large satellites, can potentially support the evolution of advanced life. The majority of stars contain one or more planets.
Psd - Planet's solar distance. A calculated value. A planet's distance from its star, combined with the effects of its atmosphere's greenhouse gasses, determines its surface temperature. Intelligent life probably requires an average planetary surface temperature of +5C to +40C degrees (Earth is currently +16C). This relatively comfortable temperature range is only found in an extremely narrow band of distance from a star.
Pm - Sufficient planetary mass. An estimated value.
Too small a mass and a planet can not hold a large enough atmosphere, have sufficient nutrients and a method to distribute them, have large oceans or have a long-lifetime molten core, all of which are necessary for the evolution of complex life.
Too large a mass and its gravitational force overpowers life, becomes a gas giant or causes excessive core outgassing of CO2 thus over-heating its atmosphere.
Po - Planets having an oxygen atmosphere that also contains ozone (Earth is 20.6% O2 and up to 8ppm O3). An unknown value and a probably exceedingly rare occurrence.
It is thought that any advanced life requires oxygen because of its highly reactive properties. An oxygen atmosphere does not naturally occur. It is produced almost entirely by lessor evolved organisms. Therefore, a planet having an oxygen atmosphere probably already has life.
Ozone is created by oxygen's photodissociation reaction with UV radiation in the upper atmosphere and to a lesser extent by lightning. Ozone must be present in large enough quantities in the upper atmosphere so as to filter out life-damaging solar UV radiation and it must also be in very low or zero quantities in the lower atmosphere as ozone itself is also damaging to life.
Pa - Planets with an atmosphere of sufficient pressure (Earth is 1.0 bars). Estimated value. A minimum atmospheric pressure is needed to produce sufficient oxygen transport for advanced life.
Pe - Planets with a low orbital eccentricity. The ideal value is 0, or perfectly circular (Earth is 0.017). An estimated value based on our solar system. How circular a planet's orbit around its star determines its temperature as it orbits. If the eccentricity is high the planet will freeze, fry, or both, as it orbits.
Pn - Percentage of planets that are...
Rocky, not a gas giant. Advanced life can not evolve on a gas giant.
Have a large variety of surface nutrients such as carbon, iron, calcium, sodium, etc. Nutrients are needed for complex evolution.
An estimated value.
Pc - Planets that were subjected to the Giant Impact Hypothesis early in their formation. Early Earth is believed to have been impacted at low angle by another planet (Theia). An unknown value but extremely rare.
This ensured that the Earth had a large and dense molten iron core to create a sufficiently sized magnetic field necessary to protect the Earth from deadly high-energy cosmic and solar particles.
Created a thin planetary crust atop a molten core ensuring plate-tectonics for nutrient materials circulation to the Earth's surface via volcanism.
Pw - Planets having sufficient liquid surface water (Earth is 70%). An estimated value. Thought to be necessary for all life. The amount of water must be ocean-sized, liquid and not covering all of the planet.
Ps - Planets having a very large, single, stable, tide-causing, natural satellite. An unknown value but very rare.
Needed to create ocean tides for additional planetary nutrient circulation.
Stabilizes the planet's axial tilt to prevent wide temperature variations over time.
Helps to keep the Earth's core molten via tidal heating (natural radioactive decay and the Earth's size also contribute).
Pr - Planets having a suitable axis rotation. The desirable range is thought to be about 10-40 hours (Earth is 24 hours). Common based on our solar system.
Needed for the development of complex rainfall bringing weather systems and for nutrient distribution.
Helps in stabilizing extreme diurnal temperature variations.
Pt - Planets having a low axial tilt. Common based on our solar system. The desirable range is 0-30 degrees (Earth is 23.5 degrees). Axial tilt creates climate seasons. Too much tilt and a planet can freeze, fry or both as it orbits.
Pes - Planets having a very long period of environmental stability. An estimated value. Unknown but probably very rare. The desirable period is 1+ billion years (Earth is 2-3 billion years). The evolution of complex life takes much time.