Class of Planets

Another question, I notice all the time the characters are talking about what class a newly discovered planet is, like K7 or M. What does that mean?

 

M-class ("Minshara-class" as determined by the Vulcans) is a designation usually given to habitable worlds like Earth (although Vulcan can presumably be M-class as well). Other letter designations are given to worlds that are less habitable or even hostile to life.

Stars can also be given letter designations like K7 with the letter representing its spectral class (or temperature) and the number its degree of visibility.

 

More precisely, the numbers are subdivisions of the temperature scale represented by the letters -- a K0 is the hottest type of K star and a K9 the coolest.

Of course, the difference is that the star letter classes are real while the planetary letter classes are an imaginary scheme invented for Trek.

 

Thank you I feel like there should be a Trek school for people who are just starting out.

 

I thought the numbers represent their absolute magnitude.

 

Here are some of the planet classes if you want to research further.

http://en.memory-alpha.org/wiki/Planetary_classification

 

I should have looked there to begin with. That website is very informative.

 

The Arabic numeral is based on temperature (as is the leading letter). There can be a Roman numeral appended to a classification to reflect luminosity, so that, e.g., our sun gets classified as G2V. The luminosity does correlate with the absolute magnitude, although not in a really easy-to-describe fashion. The lower the Roman numeral, though, the brighter the star.

 

I've been at this for nearly 30 years, and I still don't know what they mean.

I find it to be pointless minutiae. I've grown accustomed to tuning any and all Treknobabble out. Makes the viewing much more enjoyable, IMO. In fact, I doubt I could sit through an episode of 90s Trek if I didn't.

 

Absolute magnitude is a number, but it's not part of the spectral type. For instance, Tau Ceti has a spectral type of G8.5V (meaning it's a main-sequence star a few hundred degrees cooler than the Sun) and an absolute magnitude of 5.69.

The Roman numerals are called luminosity classes, but they're essentially size classes -- V is for main-sequence stars, i.e., normal stars in the stable part of their lifespan like the Sun is now, while the other classes are basically for stars that are past their main-sequence lifespans and swelling up into giants -- IV for subgiants, III for giants, II for "bright giants," and I for supergiants.

http://en.wikipedia.org/wiki/Stellar_classification

 

Also, does "class of planets" make anyone else think "Hack the planet!"?

 

True. Though, I'm certain that one day, there will be a real planetary classification scheme. That seems almost inevitable, since we keep discovering more and more exoplanets, and new methods to gradually deduce more of their properties ...

 

^Yeah, but I doubt it'll be a letter scheme, because that's already taken by stars.

Although there are some scientists who came up with a planetary classification scheme that does use letters to identify several distinct types, and that does in fact use M for Earthlike planets as an intentional Trek nod:

http://phl.upr.edu/library/notes/athermalplanetaryhabitabilityclassificationforexoplanets

 

I like to attempt to understand what they are talking about but I can't grasp any of it. So glad I'm not the only one.

 

Nah. Not me. But my cultural awareness greatly drops off after 1992.

 

We can probably rest assured that nobody really "understands" the planetary designation system of Trek, least of all the writers themselves. But the backstory of the system is known to some degree, and we can derive our own interpretations based on that.

The backstory starts with Class M, apparently the first designation invented: it designates Earth-like worlds, simply enough, but is also the middle letter in the alphabet. The writers of the original show only added Class K, which is a tad more hostile (inhabitable only with the help of pressure domes, goes the description). But after that, some other writers got and put to use the idea that the more distant a letter from M, the more hostile the world. Hence, Class Y for a really, really hostile world in VOY episode "Demon".

Other letters have been thrown about more or less without plan or concern, but that works to our advantage, as we can be the ones to retroactively invent the plan. And the simplest "plan" is the "original" one: the middle of the alphabet says "best habitable, best exploitable", while the ends describe "not habitable, not exploitable", and the letters in between describe not only decreasing levels of habitability, but also varying levels of exploitability. It isn't a simple scale from Earthlike gravity to crushing or nonexistent, or from Earthlike temperature to scorching or freezing, obviously - it's something realistically complex, something obvious to the futuristic space exploiters of tomorrow who have learned which parameters or parameter combinations really matter when founding a colony...

Timo Saloniemi

 

Agree to your points. Also, your use of 'futuristic space explorers of tomorrow' makes me think of things like this...

 

Risa would be a "class F."

(Frisky)

 

Frisky is good.

 

This is a fun topic!

The book "Star Trek Star Charts" had one of the better listings of the in-universe planetary classification system, including examples. I could not comment on how accurate the star class system was in it's terms.

Here are some other fun things I found, since I could not find a picture of the examples from the Star Charts:

http://www.startrekmap.com/library/objects/planetclass.html

Here's a text based break down of the list found in the book:
http://memory-beta.wikia.com/wiki/Planet