The HR diagram was created by Ejnar Hertzsprung and Henry Norris Russell. They formed this chart in the early 1900's. They classified the stars by their temperature against their luminosity. The blue and the white stars are the hottest, and the red, orange, and yellow stars are the coolest. The stars are then classified by their size. Giants and Supergiants, Main Sequence, and dwarfs. Stars along the Main Sequence are the most common in size and temperature. The Sun, in which out Solar System rotates around, is found in the Main Sequence group of stars.
Commas always follow these clauses at the start of a sentence. If a dependent clause ends the sentence, however, it no longer requires a comma. Only use a comma to separate a dependent clause at the end of a sentence for added emphasis, usually when negation occurs. 3. Use commas to offset appositives from the rest of the sentence. Appositives act as synonyms for a juxtaposed word or phrase.
When to Use Commas. Mouse-over the commas for a pop-up explanation. Click on the commas for further explanation of the rules of comma usage being used. Use a comma to separate the elements in a series (three or more things), including the last two. He hit the ball, dropped the bat, and ran to first base.. You may have learned that the comma before the and is unnecessary, which is fine if you're in control of things. However, there are situations when, if you don't use this comma (especially when the list is complex or lengthy), these last two items in the list will try to glom together (like macaroni and cheese). Using a comma between all the items in a series, including the last two, avoids this problem.