Just as the revolution of the earth about the sun defines the length of the year, the rotation of the earth on its axis defines the length of the day.
(the rotation of the earth on its axis; defines; the length of the day; T:Just as the revolution of the earth about the sun defines the length of the year)
the rotation of the earth on its axis
defines
the length of the day T:Just as the revolution of the earth about the sun defines the length of the year