A little app (app is the new word for page right?) to explain the days of the week.

The circle shows the day from sunrise today until sunset today, followed by the night from sunset today until sunrise tomorrow, in darker colours.

The ancients (i.e. I am too lazy to look up who) divided the day into 12 and the following night into 12. Each ‘hour’ thus produced was assigned a planet, in order of the speed they move across the sky:

  • Saturn (slowest)
  • Jupiter
  • Mars
  • Sun
  • Venus
  • Mercury
  • Moon (fastest)

And so on, starting with Saturn again.

If you run this app on a Sunday, you’ll see the Sun (yellow) gets the hour beginning with sunrise, followed by Venus, Mercury, etc., all the way round to the last hour of the day (Saturn), and further on to the hour just before sunrise tomorrow (Mercury)

The planet after Mercury is the Moon, so the Moon gets the hour beginning with sunrise on the next day, i.e. Monday.

Likewise the last hour of Monday night is Jupiter’s, so Tuesday starts with Mars (French ‘mardi’), Wednesday with Mercury (French ‘mercredi’), Thursday with Jupiter (French ‘jeudi’), Friday with Venus (French ‘vendredi’), and Saturday with Saturn.

Although most related languages have replaced some of the days in this scheme, Welsh retains the complete set.