phases of moon question

I can't help but think that this is a trick question on a quiz.

If you see the moon rise at 9 in the evening then it should be a waxing
gibbous (heading towards full), because the the earth rotates clockwise, and
the moon revolves anti-clockwise around the earth, right?

The answer on the quiz is a waning gibbous. Who is correct, the instructor
or me?

Wasn't it Neil W who wrote:
I can't help but think that this is a trick question on a quiz.

If you see the moon rise at 9 in the evening then it should be a waxing
gibbous (heading towards full), because the the earth rotates clockwise, and
the moon revolves anti-clockwise around the earth, right?

The answer on the quiz is a waning gibbous. Who is correct, the instructor
or me?

It could be either.

On 16 Jul 2008 I will see a moonrise at 20:56:00 when the moon is at
phase 94.7 and 2 days short of being full, but an observer 20 degrees
south of me sees the 16 Jul moonrise at 19:10:37. Their 21:08:38
moonrise occurs on 19 Jun 2008, one day after the full moon.

If you allow for daylight savings time, then the 23 Aug 2008 moonrise at
21:09:22 DST from where I am will almost be last quarter: Phase 61.9%.
(Last quarter will be achieved at 01:49 24 Aug 2008.)

--
Mike Williams
Gentleman of Leisure

On Mon, 17 Mar 2008 22:49:28 -0400, "Neil W"
wrote:

I can't help but think that this is a trick question on a quiz.

If you see the moon rise at 9 in the evening then it should be a waxing
gibbous (heading towards full), because the the earth rotates clockwise, and
the moon revolves anti-clockwise around the earth, right?

The answer on the quiz is a waning gibbous. Who is correct, the instructor
or me?

Consider the average situation. A full moon will rise at 6PM just as
the sun sets.

If the moon rises earlier, it is in the sky with the sun. It has not
yet reach full and must be waxing.

If it rises later, the sun has already set. It is past full and must
be waning.


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"Neil W" wrote in message
...
I can't help but think that this is a trick question on a quiz.

If you see the moon rise at 9 in the evening then it should be a waxing
gibbous (heading towards full), because the the earth rotates clockwise,
and
the moon revolves anti-clockwise around the earth, right?

The answer on the quiz is a waning gibbous. Who is correct, the instructor
or me?

You lose one mark. Think about what happens near the equinoxes. When the
sun sets at 6pm, a full moon rises at ~6pm. So a moon rising 3 hours later
will be waning gibbous.

Tonight's moon (18 March) is waxing gibbous. It's already above the horizon
when the sun sets. You can check this if it happens to be clear.

--
Mike Dworetsky

(Remove pants sp*mbl*ck to reply)

In article ,
Neil W wrote:

If you see the moon rise at 9 in the evening then it should be a waxing
gibbous (heading towards full), because the the earth rotates clockwise, and
the moon revolves anti-clockwise around the earth, right?

The earth rotates on its axis is the same direction as the moon rotates
about it: anticlockwise when viewed from above the north pole.

(So the sun appears to rotate clockwise.)

At the new moon the sun and moon rise at the same time. Over the
course of a month the moon "falls behind" the sun, so that after
two weeks it's 180 degress behind it. A waxing moon is less than
180 degrees behind the sun, a waning moon more than 180.

A full moon rises at sunset, a waxing moon before sunset, and a waning
moon after. So unless the sun sets after 9pm (which it does sometimes
if you're far enough north or south), a moon that rises at 9pm will
be waning.

-- Richard
--
:wq

In article ,
Neil W wrote:

It shows a person standing at 9pm looking (dotted line) towards the horizon
at the rising moon. I must be doing something wrong, but I can't figure
what.

As I said already, the earth rotates on its axis in the same direction
as the moon orbits the earth: anticlockwise viewed from above the north
pole. When it's noon here, it 6am in America.

-- Richard

--
:wq

"Richard Tobin" wrote in message
...
In article ,
Neil W wrote:

It shows a person standing at 9pm looking (dotted line) towards the
horizon
at the rising moon. I must be doing something wrong, but I can't figure
what.

As I said already, the earth rotates on its axis in the same direction
as the moon orbits the earth: anticlockwise viewed from above the north
pole. When it's noon here, it 6am in America.


Doh! Thanks!