Solid angle a solid angle in steradians is the following ratio: where A is the spherical surface area and r is the radius of the considered sphere. Solid angles are often used in physics, in particular astrophysics. The solid angle of an object that is very far away is roughly proportional to the ratio of area to squared distance. Here "area" means the area of the object when projected along the viewing direction. The solid angle of a sphere measured from any point in its interior is 4 sr, and the solid angle subtended at the center of a cube by one
Solid nitrogen of Pluto. The thermal conductivity of solid nitrogen is 0.7 W m K. Thermal conductivity varies with temperature and the relation is given by "k" = 180.2×T watts per kelvin. Specific heat is given by 926.91×e joules per kilogram per kelvin. Its appearance at 50 K is transparent, while at 20 K it is white. Nitrogen frost has a density of 0.85 g cm. As a bulk material the crystals are pressed together and density is near that of water. It is temperature dependent and given by ρ = 0.0134"T" − 0.6981"T" + 1038.1 kg/m. The volume coefficient of expansion