PMO stands for planetary-mass-object. Astronomers are finding PMOs in many places. The problem is Astronomers don’t know what they really are. PMOs are not planets, because they are not in orbit around a star. They have been found to range in temperature from 3,140 Degrees F to –280 degrees F. They have been found in the Trapezium Cluster in the Orion Nebula, in the Upper Scorpius star-forming region, and in the Taurus and Chamaeleon Molecular Clouds.

PMOs range in size from 5 to 12 Jupiter masses. For an object to collapse under its own gravity and form a star, it has to be over 12 Jupiter-masses. The theory of the minimum mass for star formation is called the Jeans mass, after the early 20th century physicist Sir James Jean. If an object is larger than 12 Jupiter masses, it falls into the category of brown dwarf. Brown dwarfs are large enough to collapse and form a star, but cannot give off much light or heat.

The International Astronomicial Union (IAU) is the organization that resolves matters of naming celestial objects. Currently, their definition of any object between 13 and 75 Jupiter-masses is called a brown dwarf, if it orbits a star or not. Any objects below 13 Jupiter-masses are sub-brown dwarfs if they are not orbiting a star. They admit it is a temporary solution until more information can be gathered on which to base a better descriptive term.