The Happenstance system is a single-star planetary system located in the Norma Arm of the Milky Way. When viewed from the Sol system, it is located 51 thousand light-years in the direction of the constellation Sagittarius.
The Happenstance system consists of a yellow dwarf star, three major terrestrial planets, three minor terrestrial planets, and one gas giant. An asteroid belt lies primarily between the first minor planet and the first major planet, and a cloud of short-period comets extends approximately 40 AU from the system's center.
The Happenstance system is of particular historical and anthropological significance. Currently, a technological civilization resides on the third and outermost major terrestrial planet, Yacnyco. What is unusual about the Yened people is that they possess technology characteristic of an interstellar civilization yet they remain solely on their home planet. This is the result of an extraordinary series of historical events that began during the 16500s; both the Yened and the Nlia civilization, which resided on the second major planet, Oseye, independently and simultaneously developed long-range communication technology. They rapidly expanded into space alongside each other but had opposing political and economic systems. A major conflict resulted with the destruction of the Nlia civilization and the emergence of a new sedentary culture on Yacnyco.
Human colonies co-exist with the Yened. Space habitats orbit around Happenstance in interplanetary space, Yacnyco, Oseye, and the system's gas giant, Delveon. Settlements are present on all of the system's minor planets, major moons, and in many asteroids.
The Happenstance system consists of one star, seven planets, 61 moons, and countless asteroids and comets.
The star Happenstance, or Gawags to the native Yened civilization, is a type G9 V yellow dwarf. It has a mass of 0.96 solar masses, radius of 1.09 solar radii, luminosity of 0.61 solar luminosity, and age of 4.88 billion years.
Herefesit is a minor planet and the innermost orbiting body in the Happenstance system. It is one of two planets that are tidally locked to the Happenstance. It has a remarkably circular orbit with a semi-major axis of 0.12 AU. This is along the inner boundary of the Happenstance asteroid belt. Herefesit has a mass of 0.006 Earth masses and diameter of 0.22 Earth diameters. Two captured asteroids, each nineteen kilometers in diameter, closely orbit along the planet's equator.
The system's second minor planet, Denenro, is also tidally locked and has a circular orbit with a semi-major axis of 0.19 AU, which places it within the system's asteroid belt. It too is orbited by a few captured asteroids. These asteroids are significantly larger than Herefesit's; the innermost two have a diameter of 52 and 100 kilometers. A third asteroid, 56 kilometers in diameter, orbits Denenro in an inclined and elliptical orbit, suggesting it was captured recently. Denenro has a mass of 0.04 Earth masses and diameter 0.30 Earth diameters.
Wasold is the system's innermost major planet. It has a thick atmosphere composed of carbon dioxide and a trace amount of sulfur dioxide.
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