Class M Planet
Class M, from the Vulcan term "Minshara," is a fictional classification for planets and planetoids in the Star Trek science fiction media franchise.
Their atmospheres are composed of nitrogen and oxygen and have an abundance of liquid water necessary for carbon-based life to exist. Extensive plant and animal life often flourishes; often, a sentient race is also present. Earth is a textbook example of a Class M world; other Class M planets that appear throughout the franchise include Vulcan, Cardassia Prime, Bajor, Betazed, Romulus, Ferenginar, and Qo'noS.
In fiction, Class M planets are similar to those suggested to be found in the real-world astronomical theory of life supporting planets found within the habitable zone (HZ), sometimes also referred to as the 'Goldilocks' zone. The Earth Similarity Index, a scale used in planetary science, includes within its classification of habitable planets (hClass) a "Class M", where the "M" stands for mesoplanet (not to be confused with Asimov's mesoplanet proposal), i. e., a planet with moderate (as necessary for liquid water) temperatures, more technically speaking: the thermal surface requirements necessary to support complex (multicellular) Earth-like life.
Read more about Class M Planet: Other Planet Classifications Based On The Star Trek Series
Famous quotes containing the words class and/or planet:
“Much of the wisdom of the world is not wisdom, and the most illuminated class of men are no doubt superior to literary fame, and are not writers.”
—Ralph Waldo Emerson (1803–1882)
“The golden mean in ethics, as in physics, is the centre of the system and that about which all revolve, and though to a distant and plodding planet it be an uttermost extreme, yet one day, when that planet’s year is completed, it will be found to be central.”
—Henry David Thoreau (1817–1862)