The Possibility of Earth-Sized Rocky Volcanically Active Planets in the Oort Cloud or Kuiper Belt

The vast expanse of the cosmos has long sparked our imagination, and one of the most intriguing concepts is the existence of an Earth-sized, rocky, volcanically active planet in the Oort Cloud or Kuiper Belt. Let's delve into the feasibility of such a planet, exploring the necessary conditions and challenges.

Conditions for Volcanic Activity and Atmospheric Pressure

For an Earth-sized planet in the Oort Cloud or Kuiper Belt to be both volcanic and have a gaseous atmosphere, it would need to possess a substantial amount of radioactive elements in its core. This is necessary to maintain a molten state and create the heat required for volcanic activity.

Phase Diagram Analysis for H2 and Helium

The phase diagram for 2H2 (hydrogen) indicates that you would require a temperature of 20 Kelvin for it to exist in a gaseous state. Helium, being lighter, can remain gaseous at even lower temperatures. Helium has two isotopes, 3He (a fermion) and 4He (a boson), which behave differently at low temperatures. Here are their phase diagrams:

For 4He:[Graph or Image showing the phase diagram]For 3He:[Graph or Image showing the phase diagram]

Note the logarithmic temperature scale in both diagrams, which highlights the distinct behavior of the isotopes.

Existence and Detection in the Kuiper Belt

Some objects in the Kuiper Belt are comparable in size to Pluto, but finding an Earth-sized planet would be more challenging. If it existed, it would likely be easily detected due to its size. Moreover, while a planet in the Kuiper Belt could be volcanically active, the chances of it having a 24 psi atmosphere are slim. The primary reasons are its relatively small size and the extreme distance from the Sun, making the surface extremely cold. At such temperatures, gases would solidify, reducing surface pressure to near zero.

Feasibility Near the Sun: Post-Glacial Core Cooling

Approaching the Sun, after about 4 billion years, any planet would have cooled considerably, and its core would no longer be molten. The gases would be frozen on the planet's surface, making it impossible for a planet to maintain a gaseous atmosphere.

Long-Term Growth and Atmosphere Composition

Earth-sized rocky planets in the Oort Cloud or Kuiper Belt would continue to collect mass and grow out of their initial size. The atmosphere would be easier to maintain due to the reduced influence of solar winds. However, the atmosphere composition would be limited due to the absence of significant oxygen. Oxygen readily reacts with hydrogen, which continues to stream in from the sun, forming water that would freeze and not contribute to the atmosphere.

The Role of Isotopes and Solar Gravitational Tides

Earth's core is believed to be molten owing to heat generated by solar-gravitational tides and radioactive decay. In the Oort Cloud or Kuiper Belt, the presence of more radioactive isotopes could maintain a molten core, while the reduced solar wind would help retain the atmosphere.