
Natural resources such as , (crude oil) and take thousands of years to form naturally and cannot be replaced as fast as they are being consumed. It is projected that fossil-based resources will eventually become too costly to harvest and humanity will need to shift its reliance to such as solar or wind power. An alternative hypothesis is that carbon-based fuel is virtually inexhaustible in human terms, if o.

These minor ‘planets’ are now divided into two classes: dwarf planets, and Small Solar System Bodies (SSSBs). Between the orbits of Mars and Jupiter lies what is termed the Main Belt of what are still universally called asteroids, the largest of which, Ceres, has been elevated to dwarf planet status.