Habitable Planets LIKE Earth... But BETTER! | Worldbuilding

World Building: Creating Habitable Planets

Introduction to World Building

• The video introduces the concept of world building, focusing on creating habitable planets and understanding what makes them suitable for life.

• Matthew, the host, mentions this video is part of a series that began with the creation of a universe and galaxy.

Overview of Planetary Formation

• The discussion zooms in on a Class B star named Primus, which has six times the mass of our sun and formed 3.1 billion years after the Big Bang.

• Primus has a short lifespan of about 100 million years before going supernova; however, it serves as a backdrop for discussing planet formation.

Introducing Locus: A Rogue Planet

• The focus shifts to a newly formed rogue planet called Locus, which will be central to future world-building discussions.

• Locus is defined by its mass (1.279 times that of Earth) and radius (1.137 times Earth's), allowing for calculations related to gravity and density.

Characteristics of Rogue Planets

• As a rogue planet, Locus does not belong to any solar system but may still be influenced by nearby black holes within its galaxy.

• It will remain free-floating within the Pava Cattus Nebula until it is captured by another solar system's gravitational pull.

Composition and Types of Planets

• The composition of Locus is discussed; it is classified as a terrestrial planet made primarily from metals and silicate rocks.

• Examples from our solar system include Mercury, Venus, Earth, and Mars; other types mentioned are gas giants like Jupiter and ice giants like Uranus.

Importance of Atmospheric Composition

• For planets supporting life, maintaining an Earth-like composition is crucial; even slight changes in elements can be hazardous.

• Adjustments are made to increase hydrogen and oxygen levels slightly while keeping water coverage around 85% to 90%.

Water Coverage on Locus

• Water's role as dihydrogen oxide (H2O), though only 0.02% of Earth's mass, significantly influences planetary characteristics despite surface coverage being over 70%.

• For simplicity in calculations regarding Locus’s mass distribution, it's proposed that water constitutes about 0.03% of its total mass.

Temperature Considerations for Rogue Planets

Understanding the Atmospheric Conditions of Locus

Temperature and Atmospheric Retention

• The temperature of Locus as a terrestrial planet is primarily influenced by its atmosphere's ability to retain heat, preventing it from dropping to the background temperature of space, which is 2.7 Kelvin (or -270°C) .

• A colder planet increases the likelihood that compositional elements will remain in its atmosphere, as they cannot reach escape velocity—the minimum speed needed for an object to break free from a planet's gravitational pull .

Calculating Atmospheric Composition

• The retention of atmospheric elements can be calculated using a specific equation based on the planet's mass, radius, and temperature relative to Earth. Resources like Artifexian’s spreadsheet can assist with these calculations .

• If Locus has an average surface temperature similar to Pluto (40 Kelvin), it would retain all elements except hydrogen; lowering this temperature slightly could allow even hydrogen to remain in the atmosphere .

State of Elements at Low Temperatures

• At 30 Kelvin, many elements that are gases or liquids on Earth would exist as solids on Locus. Only helium, hydrogen, and neon would remain gaseous under these conditions .

• The atmosphere at this stage would predominantly consist of hydrogen and helium with trace amounts of neon; other gases like oxygen and nitrogen would be frozen or combined into minerals due to low temperatures .

Historical Context and World-Building Implications

• Approximately 100 million years before entering the solar system, Locus may have been used as a mining colony by a space-faring species. This brief habitation could lead to significant storytelling opportunities regarding ancient civilizations and their impact on Locus’s environment .

• The existence of advanced life forms capable of surviving extreme conditions raises questions about potential interactions with future life forms evolving on Locus. This scenario opens avenues for exploring themes such as panspermia—the idea that life can be seeded across planets through biological material left behind by alien visitors .

Summary of Planetary Characteristics

• In summary, Locus is characterized as a terrestrial planet larger than Earth but currently uninhabitable due to its frozen state while being a rogue planet. It has had transient visitors whose remnants may influence future life evolution on the planet .