Eas100 lecture 3 the earth in space and time. Consists of: one single star (our sun, numerous objects that are orbiting the sun, such as, planets, dwarf and minor planets, comets, satellites orbiting planets (called moons or moonlets depending on size) In relation to other known stars in our universe, the sun is very average (medium in size, heat intensity, and in age). In relation to earth, the sun is a giant: 109 times earth"s diameter, 300 000 times the mass. The source of solar energy is the nuclear fusion of hydrogen to make helium (38% h, 62% he). The sun is not just a ball of fire! Layers from outermost to innermost are: corona, chromosphere, photosphere, convective layer, radiative layer, core. Energy from the sun comes to the earth in a planar fashion. Because earth is tilted and spherical, we don"t receive the sun"s energy equally.