Nerrivik (designated HD 219134 h or HR 8832 h) is a gas giant exoplanet, the fifth, final, and largest planet of the Niobe system. It is close to the size of Jool and has a very similar color scheme, suggesting a similar formation history. The planet is circled by two icy rings and a system of three moons, one with exotic ammonia-based life. The planet itself is quite exotic, with a chlorine haze and rains of salt.
Mass and Radius
Nerrivik is a large, gaseous planet. It has a radius of 4,590 kilometers - about 8.25 times the size of Kerbin, or about 83% the size of Jool. However, it is significantly more massive than the latter. While Jool has eighty times the mass of Kerbin, Nerrivik instead has about 108 times Kerbin's mass. This leads to a higher density (~0.813 g/cm^3) and gravitational pull (1.59g) than Jool, suggesting a larger core of ice and rock. Otherwise, the two planets are nearly identical.
Orbit and Rotation
Nerrivik has a large orbit around Niobe. It takes a little over 6 Kerbin years (about 2,629 days) to complete one full revolution around its parent star. The planet's semi-major axis is around 42,229,550 km, compared to that of Kerbin being about 13,599,840 km. While this is less than that of Jool, the lower mass of Niobe gives the two planets about the same orbital period.
Nerrivik is not a synchronous rotator, given that it orbits millions of kilometers away from the zone where gravitational forces would be enough to tidal lock it with Niobe. It has a rotation period just shy of about 23 hours - over three and a half times slower than that of Kerbin.
Weather and Climate
Being a gas giant with no solid surface, Nerrivik has very similar weather to Jool. The top of the atmosphere is stretched into about three major cloud belts. Darker gases are found around the borders of each cloud belt. Meanwhile, the center of the belts are composed of lighter gases. These appear to be potassium for the darker regions and ammonium (NH3) for the lighter regions. While the entire planet looks green, these gases do exist. The green color is due to an upper level haze of chlorine - similar to that of Jool.
The presence of both chlorine and potassium (along with trace amounts of sodium) provide a paradox for the atmosphere of Nerrivik. Due to the unstable nature of these elements, chlorine is almost guaranteed to combine with either potassium or sodium to form salts in the form of KCl and NaCl. Over time this should deplete the storage of either chlorine or potassium/sodium, yet both are still there. One possible solution is a bizarre "salt cycle". The way this works is that salt forms in the upper atmosphere, which rains down to lower layers. The internal heat from Nerrivik causes the salt particles to transition to a liquid and, eventually, a gas again. This salt gas breaks apart into its individual elements and rises back up into the upper atmosphere. However, some of the potassium and sodium does not make it back up - hence the fact that Nerrivik has rather small amounts of dark regions caused by these elements.
Nerrivik's climate is very cold due to its distance from Niobe. The average equilibrium temperature of the planet is just 95 degrees Kelvin (-178*C or -289*F). The planet's temperature, however, does increase the deeper and deeper you go into the planet. Like with Jool, this is because of internal heating from extreme internal pressures. This internal heating inside Nerrivik is very similar to that of Jool, since their atmosphere have almost the same pressure. Nerrivik has just slightly less atmospheric pressure than Jool - 13.03 atm compared to 15 atm.
Nerrivik has a thin system of rings. Two main, dusty rings encircle the planet. Both are sheparded by two tiny ice moons.
Nerrivik has a total of three moons. While three more are planned, these are the only ones currently in the mod.
- NK-1: The first and largest of Nerrivik's Shepard Moons. It is heavily pockmarked and coated in a goo-like layer of methane ice.
- NK-2: The second and smallest of Nerrivik's Shepard Moons. It has a rather eccentric orbit, taking it closer to the rings than NK-1. NK-2 is coated in blue ice from the rings - or maybe the blue ring dust comes from NK-2.
- KOKKSAUT: The only major moon of Nerrivik (as of now). It is a bizarre moon with black oceans of liquid ammonia and large continents - rather Kerbin-like in geology. However, the surface is covered in green ammonia-based microbes that take their energy from chemosynthesis.