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O B A F G K M

This is the Harvard Spectral Classification System for the stars. Each letter corresponds to a certain type of spectrum, and therefore color, of a star. The letters also correspond roughly to the temperatures, with O, the bluest, being the hottest. Why aren't the letters in alphabetical order? Well, they started out in order, according to the strength of the Balmer lines in the spectra, but then some of the letters turned out to be equivalent, so they dropped those. Then the order was rearranged according to temperature. Rather than rename the spectral types, they simply placed them in the correct order, and so we have OBAFGKM. To remember this order, we like to invent mnemonics. The most common one is:

Oh, Be A Fine Girl, Kiss Me

Or, if you're a girl, you can say:

Oh, Be A Fine Guy, Kiss Me

There are three more types of stars, that are mixed in with the M giants. These are R, N, and S. So, adding these letters to the mnemonic we can have:

"Oh, Be A Fine Girl, Kiss Me." "Right Now?" "Sure."

Here's a list of some other mnemonics I have collected. If you come up with any, with or without the RNS, please send it in. I'll give you credit for it.

Note: Recently two more types of stars have been added to the sequence, cooler even than the M stars (that is, less hot than M stars). These have been named L and T stars. I still don't have many mnemonics for this sequence, so if you know any more, please send them in!

O B A F G K M L T :

Oh Be A Fine Girl Kiss My Lips Tonight

--Submitted by Steffen Knollmann

Oh Brilliant And Fiery Geminids, Kindle My Lamp Tonight --Newly added
--Submitted by Richard Stratford

Officially, Bill Always Felt Guilty Kissing Monica Lewinsky Tenderly

O B A F G K M :

Only Boys Accepting Feminism Get Kissed Meaningfully

--unknown

Optical Binary Affairs Fundamentally Generate Keplerian Marriages
--"Introductory Astronomy and Astrophysics" (Zeilik * Gregory)

Only Bold Astronomers Forge Great Knowledgeable Minds
--"Introductory Astronomy and Astrophysics" (Zeilik * Gregory)

Occasional Banter And Feghoots Graciously Kill Monotony
--SummerDale Beckstrand (This one's for Dr. Taylor, the king of Feghootry)

Orange Banana Apple Fig Grape Kiwi Mango
--J. Snedeker

Orion, Badly Armored, Faught Gargantuan's Killing Machine
--David Carroll

October Babies Always Find Great Kostume Masks
--Oblivion

Odin Bityi Anglichanin Finiki Geval Kak Morkov'
--km (from Russian: one beaten English chews dates like a carrot)

Only Bored Astronomers Find Gratification Knowing Mnemonics
--Taken from Answers.com

Omnivorous Butchers Always Find Good Kangaroo Meat
--Dr. Matt Adams

O B A F G K M (R N S):

Orbiting Bodies Always Follow Gravitational Kinetic Modes (Round Nearest Star)

--Newly added

--the bert

Out Beyond Andromeda Fiery Gases Keep Making Really Nifty Stars
--unknown

Overseas Broadcast: A Flash Godzilla Kills Mothra (Rodan Named Successor)
--unknown

Octopus Brains, A Fine Gastronomical Kitchen Menu, Require No Sauce
--unknown

Oh, Be A Fine Guy, Kill My Roommate Now, Sweetie
--Gary Fouts

O Belli Astri, Forma Gloriaque Kanatis. Me, Reges Noctis, Serenatis.
--SummerDale Beckstrand *Kanatis is really spelled "Canatis", but as there are no "K"s in Latin, I had to make do with a "C"

Ordinary, But Awesome, Far-reaching Gases Kindly Make Regal New Stars
--SummerDale Beckstrand

Oh, Beautiful Angels Fly Gracefully, Kneel Mercifully, Reviving Needy Souls
--SummerDale Beckstrand

Only Big Astronomy Federal Grants Keep Money. Research Needs Support!
--Taken from Answers.com

Oh, Boy! Another Failing Grade Keeps Me Reconsidering Night School!
--Dr. Taylor

Add your own mnemonic to this list by filling out the following form:

NOTE: My forms are temporarily out of service, so for now, to submit a new mnemonic, email it to WebSDB@gmail.com with the word "mnemonic" somewhere in the subject line. In the body of the email specify the name with which you would like to be credited (or "Anonymous") and whether or not you would like your name linked to your email/website. And be sure to use an accepted sequence of letters (i.e. OBAFGKM, OBAFGKMRNS, or OBAFGKMLT. Thanks!
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