ok austronamers heres an interesting question?

Question

the other day i was looking up at the ski in plain daylight and i noticed that i could see the moon

as you know this is rare since the sun was also up

anyways i could see the sun completly but the moon looked like a half moon

this doesnt make since, if i can see the whole sun and only part of the moon it means the earth should be eclipsing the moon right ?

but then how is this possible ?

i wish i could draw a picture
but it was something like this

moon (1/2) Sun


me

so about 60 degrees up from horizon


how could this happen ??

Answer 1

I get the impression that you believe the phases of the moon are caused by the Earth's shadow. This is not the case. The "shape" of the moon is based on the angle from which we are seeing the moon related to the angle from which the sun's light is falling on it.

Also seeing the moon during the day is not rare. Thick crescents and half moons are easily viewed during the day.

This picture I created should help you understand what you saw:

http://public.clunet.edu/~sjfahmie/halfmoonday.jpg

Answer 2

A half moon is possible to see because the angle between the sun and moon is half way to a full moon which occurs when the sun and moon are directly opposite from the earth or a new moon when the moon aligns directly between the earth and the sun. So a half moon would occur when the moon is only half way to being full or new. You're right, this would be much easier if a drawing could be made to show these relationships of the sun, the moon and earth but I hope this gives you some idea of how it works.

Answer 3

The Moon turns around the Earth in approximately one month, relative to the Sun (in fact, that was the origin of the "month" as a unit of time).

When the Moon is one quarter way around the orbit, it appears (from our point of view) about 90˚ to the East of the Sun (if you live in the northern hemisphere, the First Quarter moon is 90˚ to the left of the Sun).

At that time, the Sun light up the Moon from the side (from our point of view) and we only see half the disk being lit. The Moon rises around noon (i.e., six hour after the Sun rises -- it takes the Earth 6 hours to turn 90˚ on its axis).

As days go on, the Moon moves on its orbit and appears further away from the Sun. The Sun is lighting more and more of the face we see, so it appears more than half.

You would see it in the eastern sky, during the afternoon (since it rises more than 6 hours after the sun rises).

At full Moon, the Moon is 180˚ from the Sun. It rises just as the Sun sets. The Sun is lighting the entire face that we see (that is why it appears "full").

After that, the Moon keeps going on its orbit. Another week and it is Last Quarter. The Moon is 90˚ to the West of the Sun and sets 6 hours before the sun sets. So, in early morning, you can see the Moon is the western part of the sky.

Then New Moon (the Moon is in the same direction as the Sun, therefore invisible for us, since the Sun is busy lighting the side that we do not see).

The cycle starts over.

Answer 4

That is a very ordinary thing to see. I see it many times a year, every year. Try looking at the Moon every day for a month and you will see what is going on. There is a definite relationship between the phase of the Moon and its angular distance from the Sun as seen in the sky. A half Moon will always appear 90 degrees from the Sun. A crescent Moon will always appear less than 90 degrees from the Sun. A gibbous Moon (more than half but less that full) will always appear more than 90 degrees from the Sun. And a full moon will always appear 180 degrees from the Sun. Since the Moon and Sun can both be in the sky at the same time except when they are exactly 180 degrees apart, it is quite common to see the Moon in the day time. It is just that most people pay no attention to the sky. Except us astronomers. The first thing I do whenever I go outside is look at the sky. When I see the Moon, I always tell my kids, "hey look, there is the Moon" to which they reply "yeah, so what". Most people just don't care and don't look and so don't know. My kids know because I point it out and tell them, but they still don't care. Sigh...

Answer 5

It happens more often than you realize. Let's "draw" a picture to show how it can happen....

Imagine a circle about the diameter of a cola can. This represents the earth. You are at the top of this circle.

Imagine another circle about the size of a dime about 18" to the right and above "earth". This represents the moon.

Now, imagine a circle about 3 times the size of a basketball about 50 yards to the left and a little above "earth". This represents the sun.

Note that there exists a direct line between the "moon" and the "sun" without "earth" being in the way. Also note that, since your position is on top of the "earth" circle, you can "see" both the "sun" and the "moon".

P.S. The relative sizes are not really accurate. I just used these sizes to help explain the picture.

Answer 6

For about a week after full moon, the moon is still in our daylight sky reflecting part of the sunlight that falls on it.
Think of the moon like a mirror - when the angle is right you can see the sun and the mirror reflecting the sunlight at the same time.
And the word is "astronomers", not "austronamers" which sounds like people that name things in Australia.

Answer 7

My word. Do you look in the sky so seldom?

The moon is often visible in daylight.

And if you had a little thought you would realise why it was half a moon. The sun being there would give the clue - it can only shine on one half of the moon, can't it.

The phases of the moon have NOTHING TO DO WITH THE EARTH'S SHADOW.

Repeat that last sentence over and over,because someone has been telling you false idiotic things.

Answer 8

You can quite commonly see the moon in the daytime.

The phase of the moon is not caused by the earth "eclipsing" it. Rather, the phase of the moon is caused because only half of the moon is illuminated by the sun. When the side facing us is not entirely illuminated, we see less than a full moon.

Answer 9

Well the event you have witnessed is just as common as seeing a moon at night. The reason that only part of the moon is lit up is because only one half is facing the sun.

http://tech.groups.yahoo.com/group/NeatAstronomy/

Answer 10

I can't wait for the lunar eclipse,to see what other smart questions are out here.