Defining the term planet is important, because such definitions reflect our understanding of the origins, architecture, and evolu-tion of our solar system. Over historical time, the objects thought to be …

Defining Planets among Planetary Bodies is Semantics, and has to be, to some degree, Arbitrary. A good definition should minimize arbitrariness, but cannot be expected to do away with it entirely. The …

Cockcroft explains that to be considered a planet today, a celestial body in the Solar System must orbit the sun, be massive enough for its own gravity to make it round, and have cleared its...

The planet definition approved by the International Astronomical Union is based on the observed architecture of the solar system, in which a small number of dominant bodies, the eight planets, …

Mercury is the planet in our solar system that is closest to our sun. Named after the Roman god Mercury who was the messenger to the gods, it is the smallest planet, and is very difficult to see …

This map shows the Earth’s physiographic features, the current movements of its major tectonic plates, and the locations of its volcanoes, earthquakes, and impact craters. The use of color and shaded …

Planet Earth From the beginning of our species, we have sought to understand our surroundings, whether that was the soil beneath our feet or the stars in. the heavens. Above, the Milky Way …