 # 6.3. What is the system behind the planetary day names?

## Description

This article is from the Calendars FAQ, by Claus Tondering claus@tondering.dk with numerous contributions by others.

# 6.3. What is the system behind the planetary day names?

As we saw in the previous section, the planets have given the week
days their names following this order:

Moon, Mars, Mercury, Jupiter, Venus, Saturn, Sun

Why this particular order?

One theory goes as follows: If you order the "planets" according to
either their presumed distance from Earth (assuming the Earth to be
the centre of the universe) or their period of revolution around the
Earth, you arrive at this order:

Moon, Mercury, Venus, Sun, Mars, Jupiter, Saturn

Now, assign (in reverse order) these planets to the hours of the day:

1=Saturn, 2=Jupiter, 3=Mars, 4=Sun, 5=Venus, 6=Mercury, 7=Moon,
8=Saturn, 9=Jupiter, etc., 23=Jupiter, 24=Mars

The next day will then continue where the old day left off:

1=Sun, 2=Venus, etc., 23=Venus, 24=Mercury

And the next day will go

1=Moon, 2=Saturn, etc.

If you look at the planet assigned to the first hour of each day, you
will note that the planets come in this order:

Saturn, Sun, Moon, Mars, Mercury, Jupiter, Venus

This is exactly the order of the associated week days.

Coincidence? Maybe.

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