In this alternate reality, "minor planet" is a broad term used to refer to a diverse array of small celestial bodies that generally orbit a star, such as asteroids, dwarf planets, natural satellites including certain smaller moons, and other trans-Neptunian objects beyond the orbit of Neptune.
The exact definition of a minor planet varies across scientific communities, but generally includes any astronomical body that has a diameter smaller than Pluto. In practice, this means that the vast majority of known solar system bodies are considered minor planets. Some organizations, such as the International Astronomical Union, further categorize these bodies into various subclasses, including asteroids, trans-Neptunian objects, and dwarf planets.
Thanks to recent advances in telescope technology and exploratory space missions, we now have a much better understanding of the diversity of minor planets in our solar system. Several minor planets, originally thought to be asteroids, have since been reclassified as dwarf planets, and some smaller moons in the orbit of Saturn, Uranus and Neptune have also been redefined as minor planets. In total, there are estimated to be over 10 million minor planets in our solar system, with very large populations in the Kuiper Belt, Oort Cloud, and the inner reaches of the solar system.
One of the most intriguing discoveries is the prevalence of water and organic material on many minor planets, raising the possibility of life - or at the very least, the potential for life - on these bodies. Ceres, for example, has been found to host water in the form of ice, while Enceladus and Europa, two of Jupiter's smaller moons, contain global oceans beneath their icy surfaces, fueled by active ocean floor hydrothermal activity. In the outer Solar System, many Kuiper Belt Objects are shown to possess complex hydrocarbon compositions, with some even containing prebiotic molecules and potential seeds of an alternate early life.
In recent decades, both robotic and manned exploration efforts have targeted minor planets, with the goal of gaining a better understanding of their composition and potential resources. Some such missions have even yielded evidence of possible primitive extraterrestrial life, such as microfossils found in the Martian minor planet Phobos. Moreover, in a few notable cases, remnants of advanced alien technology have been discovered on certain minor planets, leading many to speculate that these bodies may have been visited or even colonized by alien civilizations at some point in the past.
The exploration and discovery of minor planets has significantly reshaped our understanding of the universe and our own planet, leading to a newfound appreciation for the beauty, diversity, and fragility of cosmic entities. By providing new insights into the building blocks of the universe and the potential for life beyond Earth, the study of minor planets has engaged and inspired generations of astronomers, scientists, and space enthusiasts.
Future exploration of the many unexplored or poorly understood minor planets throughout the cosmos is sure to lead to further exciting discoveries, pushing humanity to the frontiers of scientific, technological, and philosophical understanding.
