Structure
Terrestrial planets all have approximately the same type of structure: a central metallic core, mostly iron, with a surrounding silicate mantle. The Moon is similar, but has a much smaller iron core. Terrestrial planets can have canyons, craters, mountains, and volcanoes. Terrestrial planets possess secondary atmospheres, generated through internal volcanism or comet impacts, in contrast to the gas giants, whose atmospheres are primary, captured directly from the original solar nebula.
Read more about this topic: Terrestrial Planet
Famous quotes containing the word structure:
“For the structure that we raise,
Time is with materials filled;
Our to-days and yesterdays
Are the blocks with which we build.”
—Henry Wadsworth Longfellow (1809–1882)
“Science is intimately integrated with the whole social structure and cultural tradition. They mutually support one other—only in certain types of society can science flourish, and conversely without a continuous and healthy development and application of science such a society cannot function properly.”
—Talcott Parsons (1902–1979)
“The verbal poetical texture of Shakespeare is the greatest the world has known, and is immensely superior to the structure of his plays as plays. With Shakespeare it is the metaphor that is the thing, not the play.”
—Vladimir Nabokov (1899–1977)