A correct answer consists of telling me the source, or origin of the
names of the days of the week,  Sunday, Monday, Tuesday, Wednesday,
Thursday, Friday, and Saturday. Where did these names come from, and
when did people start using them on the calendar?

Hello, tibiaron, 

Following are some nice links which you can print out. 

Etymology and History : The Origin of the Names of the Days of the Week:

Sunday: Sun:
http://www.combase.com/~westilson/sunday.gif

Monday: Moon:
http://www.combase.com/~westilson/monday.gif

Tuesday: Tiw (God of War):
http://www.combase.com/~westilson/tuesday.gif

Wednesday: Woden (God of Wisdom):
http://www.combase.com/~westilson/wdnesday.gif

Thursday: Thor (God of Thunder):
http://www.combase.com/~westilson/thursday.gif

Friday: Frigga (Goddess of Married Love):
http://www.combase.com/~westilson/friday.gif

Satuday: Saturn:
http://www.combase.com/~westilson/saturday.gif

What Is the Origin of the 7-Day Week?
"Digging into the history of the 7-day week is a very complicated
matter. Authorities have very different opinions about the history of
the week, and they frequently present their speculations as if they
were indisputable facts. The only thing we seem to know for certain
about the origin of the 7-day week is that we know nothing for
certain."
"The common explanation is that the seven-day week was established as
imperial calendar in the late Roman empire and furthered by the
Christian church for historical reasons. The British Empire used the
seven-day week and spread it worldwide. Today the seven-day week is
enforced by global business and media schedules, especially television
and banking."

What Do the Names of the Days of the Week Mean?
"An answer to this question is necessarily closely linked to the
language in question. Whereas most languages use the same names for
the months (with a few Slavonic languages as notable exceptions),
there is great variety in names that various languages use for the
days of the week. A few examples will be given here."

"Most Latin-based languages connect each day of the week with one of
the seven "planets" of the ancient times: Sun, Moon, Mercury, Venus,
Mars, Jupiter, and Saturn. French, for example, uses:

English  -  French  -  "Planet"
Monday      lundi 	Moon
Tuesday     mardi 	Mars
Wednesday   mercredi 	Mercury
Thursday    jeudi 	Jupiter
Friday 	    vendredi 	Venus
Saturday    samedi 	Saturn
Sunday 	    dimanche 	(Sun)

"English has retained the original planets in the names for Saturday,
Sunday, and Monday. For the four other days, however, the names of
Anglo-Saxon or Nordic gods have replaced the Roman gods that gave name
to the planets. Thus, Tuesday is named after Tiw, Wednesday is named
after Woden, Thursday is named after Thor, and Friday is named after
Freya."
http://webexhibits.org/calendars/week.html

Various weekday connotations and origins:
http://webexhibits.org/calendars/week-connotations.html

Thank you for the enjoyable question. If you have any questions,
please post a clarification request before closing/rating my answer.

Thank you,
hummer

Google Search Terms Used:

origin  "days of the week"

It's amazing how far back some of the things we take for granted can
be traced.  The one sentence you found "The only thing we seem to know
for certain
about the origin of the 7-day week is that we know nothing for
certain." sure says it all.  I don't care for the answer, but I can't
complain about your skill at finding it, and fast too.  You deserve
five stars for a great job.  Thanks.

Don't forget tuesday comes for many greek gods ---

Hi ripcurl, thank you for your comment. You'll find the Greek
days/Gods on this link:

Monday    - Selene  	
Tuesday   - Ares  	
Wednesday - Hermes  	
Thrusday  - Zeus  	
Friday    - Aphrodite 
Saturday  - Chronos  	
Sunday    - Helios
http://webexhibits.org/calendars/week-connotations.html

hummer

I think a fairly obvious origin can be found from the Genesis account
in God's Word.  Here we are told that God created everything in 6 days
and rested on the 7th.  Going beyond all the controversy that brings
up, I would imagine most would date the writings of Genesis certainly
before the Roman Empire.   And if you go with the opinion of most
Biblical scholars, the date would be around 2000 B.C.  So I'd guess
that puts the Genesis account in a pretty good running for "likely"
origin.(at least when it comes to accounting for the number of days in
the week)

Thank you, tibiaron, I appreciate your nice note, rating, and thank
you. The percentage of what humans know is small compared to what is
out there to learn, and much of what they think they know today turns
out to be wrong tomorrow. And so it goes...hummer