On Sunday, December 2, 2018 at 3:33:31 PM UTC-7, Chris L Peterson wrote:
On Sat, 1 Dec 2018 19:04:20 -0800 (PST), Quadibloc
wrote:

I was looking for an accurate value for Martian circumpolar motion - I thought I
had that on my site as well, and I did, but I just looked in the wrong place -
and found *this* web site...

https://www.windows2universe.org/kids_space/period.html

which says
" Earth's day (or rotational period) is exactly 23.9345 hours (or, 23 hours, 56
minutes, 4.2 seconds)."

I'm not sure what you're objecting to. The failure to qualify "day" as
"stellar day"? That seems pretty minor considering that the sentence
immediately before the one you quote very explicitly defines "day" as
the rotational period... which obviously is the value they state.

The sentence immediately before was:

'We call the rotational period of Earth a "day".'

It was not obvious what value of "we" should be applied to that sentence. Usually, sentences like this beginning with "we" give it the meaning 'the general community of speakers of English', as in:

When the local government demands a portion of your earnings by force, we call it "taxes" rather than a protection racket.

Thus, I find that sentence to aggravate rather than ameliorate the issue.

In many contexts, "day" is reasonably assumed to mean "solar day", but
I don't see the problem if the context makes it clear what kind of day
is under discussion (and the word "day" in isolation is always
ambiguous in meaning).

Basically, although I recognize what he is wrong about, I still would stand with
Oriel on *this* point.

Earth's day is 24 hours. Period. Full stop. The only if, and, or but to that I
accept is the one he would call "pretentious" - including a tiny fraction of a
second, since it _is_ slightly longer than 86,400 SI seconds, or 86,400 of the
Ephemeris seconds on which their length was based.

Yes, there are contexts where one could put the synodic day and the sidereal day
on an equal footing - and the tropical, sidereal, and anomalistic years as well.
Those are technical contexts, for the use of astronomers in communicating with
other astronomers.

Not for anything intended to face members of the general public, or, worse yet,
children.

Oriel errs by insisting that Earth's day must also be its rotational period -
that previous error makes the same error of equating the two, but in the
opposite direction! It is precisely this sort of sloppiness that *created* Oriel
in the first place!

John Savard