Determination of the day of the week row C) to find the dominical letter that is E. The letter for September 18 is B, so the day of the week is Thursday. Use 16 (in the Julian century row, column E) and 76 (in row D) to find the dominical letter that is A. February 23 is a "D" day, so the day of the week is Wednesday. In a handwritten note in a collection of astronomical tables, Carl Friedrich Gauss described a method for calculating the day of the week for 1 January in any given year. He never published it. It was finally included in
IAU definition of planet An alternate proposal included dwarf planets as a subcategory of planets, but IAU members voted against this proposal. The definition was a controversial one, and has drawn both support and criticism from different astronomers, but has remained in use. According to this definition, there are eight known planets in the Solar System. The definition distinguishes planets from smaller bodies and is not applicable outside the Solar System. To date, there is no accepted definition of extrasolar planets, or exoplanets. In 2007, an IAU working group issued a position statement that proposes to distinguish exoplanets from brown dwarfs on the basis