A planet is only one type of world which might be chosen as a setting for a geofiction. Moons are another popular setting especially in science fiction. There are many other celestial bodies that could be called a world. Planets make great earth like worlds and are the most popular setting for Geofictions.
IAU Definition of a Planet
In 2006 the International Astronomic Union (IAU) changed the definition of a planet. The full resolution was:
The IAU therefore resolves that planets and other bodies in our Solar System, except satellites, be defined into three distinct categories in the following way:
(1) A “planet” is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighborhood around its orbit.
(2) A “dwarf planet” is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, (c) has not cleared the neighborhood around its orbit, and
(d) is not a satellite.
(3) All other objects, except satellites, orbiting the Sun shall be referred to collectively as “Small Solar-System? Bodies”.
The eight recognized planets by the IAU are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.
Links for Learning
Questions for World Builders
These questions can also be applied any type of world.
- What is the general shape of your world?
- How did it become this shape?
- What is the distance of the world from the nearest Sun?
- Does your world have any moons or other satellites?
- How old is your world?
- How big is your world?
- If you dissected your world in half, what would you find beneath its crust?
- What are the core compounds and chemicals that are found in your planets atmosphere.
- What is the gravity of your planet?
- Does your world tilt?
- If your planet has poles, where are they located?
- Map the orbit of your world around its solar system.
- Draw a segmented diagram of your planet showing the various layers within.
- Jot down at least 10 dot points about the creation of your world in scientific terms.
- Make the shape of your planet out of paper mache.