Where did the days of the week get their names from?

In pagan Britain the days of the week took their names from heavenly bodies or the gods associated with them. So, Sunday was the day of the Sun, and Monday that of the Moon. Tuesday seems to have been named for a warrior god named Tiw, Wednesday for Odin, chief of the gods. Thursday was named for Thor, the Teutonic god of thunder (pictured, with his hammer); Friday was the day of Frigg, wife of Odin; and Saturday was the day of Saturn, the planet and Roman god of agriculture. The names endured in Britain after its conversion to Christianity, though elsewhere in Europe, Church terminology sometimes triumphed over the pagan precedents. In France, for example, Sunday is Dimanche and in Portugal Domingo, both signifying the Lord’s Day.

The months of the year are based on Roman models:

January: Janus, god of thresholds and beginnings
February: from februum, purification, a month of ritual cleansing
March: from Mars, god of war
April: from aperire, to open, a month when leaves open
May: Maia, goddess of growth
June: Juno, goddess and wife of Jupiter
July: from Julius Caesar, who reorganised the calendar
August: from the emperor Augustus
September: from septem, seven*
October: from octo, eight*
November: from novem, nine*
December: from decem, ten*

 * seventh, eighth, ninth and tenth months counting from March, the first month of the old Roman calendar.