The Media Science Guide to Planetary Classification
Posted: 14.03.2006, 12:03
A quick guide for the perplexed.
Extrasolar Planets
Mass > 100 Earths: Jupiterlike
All planets bigger than 100 Earths are gas giants like Jupiter. This classification applies to all objects which are not fusing stars. All objects in this range are similar to Jupiter, regardless of location in a solar system. The term "brown dwarf" leads to confusion and should be avoided.
30 Earths < Mass < 100 Earths: Saturnlike
All objects in this mass range are gas giants like Saturn, regardless of position in a solar system. Planets in this mass range always have some kind of ring system when depicted.
Mass < 30 Earths: Super-earths
All planets in this mass range are rocky or icy worlds with a solid surface and rocky core. They usually have thin atmospheres. Worlds below about fifteen Earth masses are "Earthlike". This applies regardless of temperature. There are no planets in this mass range which are gas giants.
Pulsar planets: Optional passing references
Pulsar planets get in the way of the magic "Earthlike" classification, so do not need to be mentioned.
Planets in multiple star systems: Tatooine-like
The term "Tatooine-like" arises because no other fictional planets have more than one sun. This remarkable innovation in science fiction is a testament to the great genius of George Lucas.
Solar system
Any object beyond Neptune: 10th planet
Any large object discovered beyond the orbit of Neptune (excluding Pluto, which is the ninth planet) is the tenth planet. The fact that this results in multiple tenth planets is irrelevant because the intervals between the discoveries is long enough for the public to forget the last one.
Inner system asteroids: Armageddon
Any asteroid in the inner solar system is an imminent threat to all life on Earth. The term "Armageddon" comes from the first and only movie to depict an asteroid impact on the Earth.
Extrasolar Planets
Mass > 100 Earths: Jupiterlike
All planets bigger than 100 Earths are gas giants like Jupiter. This classification applies to all objects which are not fusing stars. All objects in this range are similar to Jupiter, regardless of location in a solar system. The term "brown dwarf" leads to confusion and should be avoided.
30 Earths < Mass < 100 Earths: Saturnlike
All objects in this mass range are gas giants like Saturn, regardless of position in a solar system. Planets in this mass range always have some kind of ring system when depicted.
Mass < 30 Earths: Super-earths
All planets in this mass range are rocky or icy worlds with a solid surface and rocky core. They usually have thin atmospheres. Worlds below about fifteen Earth masses are "Earthlike". This applies regardless of temperature. There are no planets in this mass range which are gas giants.
Pulsar planets: Optional passing references
Pulsar planets get in the way of the magic "Earthlike" classification, so do not need to be mentioned.
Planets in multiple star systems: Tatooine-like
The term "Tatooine-like" arises because no other fictional planets have more than one sun. This remarkable innovation in science fiction is a testament to the great genius of George Lucas.
Solar system
Any object beyond Neptune: 10th planet
Any large object discovered beyond the orbit of Neptune (excluding Pluto, which is the ninth planet) is the tenth planet. The fact that this results in multiple tenth planets is irrelevant because the intervals between the discoveries is long enough for the public to forget the last one.
Inner system asteroids: Armageddon
Any asteroid in the inner solar system is an imminent threat to all life on Earth. The term "Armageddon" comes from the first and only movie to depict an asteroid impact on the Earth.
Oh, those last few entries were good...!
