1.  Large mass in outer space 

Although planets do have a large mass that is located in outer space, there are specific requirements for the size of the mass to ensure that the mass is large enough to cause the planet to turn into a spherical shape. Having mass is a non-criterial attribute of a planet. 

 

2. Moons 

Six of the eight planets currently have moons. Venus and Mercury, the two smallest planets, do not. Scientists believe that Venus and Mercury, the two closest planets to the sun, do not have any moons due to their closeness to the sun and the sun's own pull of gravity versus the amount of gravity each of the two planets have. Although the remaining six planets have at least one moon, it is not a criterial attribute to be a planet. 

 

3. Atmosphere

Each planet has an atmosphere. Each planet has a different combination of gases that combine to create their atmosphere. Although each planet has a varying atmosphere, it is not a criterial attribute to become a planet.