Two questions about the moon

Exit

1. I kinda feel dumb for asking this, but why is it that sometimes we don't see a full moon?

2. I'm in Western Canada, and this might be the same everywhere, but at about 4pm both the sun and moon are visible in the sky. How is this? Surely that means that on the opposite side of the world, neither the sun or moon is visible? But surely at least one of them is always visible.

vibe666

1. when you see the moon, you are seeing the light from the sun reflected off it's surface. when you don't see the whole of the moon (sounds like a song. ) this is because of one of twon things. a. either the earth is casting a shadow on the moon because it is sitting partially between the moon and sun, or b. you are viewing the moon from the side relative to where the sun is shining on it. think of it like you holding a ball out in front of you facing sideways to the only light in the room. you see half the ball light and half dark.

2. the moon goes round the earth and the earth goes round the sun in the opposite direction, but not at the same speed, so sometimes you see more of the moon than others because it is at different phases of it's rotational cycle relative to the earth and sun, sometimes in front of the earth, sometimes behind, or anywhere in between.

if i remember my brief lessons on the subject at school, the earth takes 24 hours to turn 360 degrees in a full circle, the moon takes 28 days (iirc) to go round the earth and the earth takes 365 (and a quarter, again iirc) days to go round the sun.

Flukey

Yesterday was the 36th anniversary of the first moon landings. They landed in the Sea of Tranquility which you can see each night the moon is visible.

ISAW

Exit wrote:

1. I kinda feel dumb for asking this, but why is it that sometimes we don't see a full moon?

Well why is it sometimes that we DO see one?


2. I'm in Western Canada, and this might be the same everywhere, but at about 4pm both the sun and moon are visible in the sky. How is this? Surely that means that on the opposite side of the world, neither the sun or moon is visible? But surely at least one of them is always visible.[/QUOTE]

How do you come to that conclusion? How is it you believe that it is "for sure" that one must be visible somewhere.

Hint: The sun isnt always visible is it since we have nighttime? soare you suggesting that every night must have the Moon? So whaT is a "NEW MOON"? and why does the Moon have phases?

ISAW

vibe666 wrote:

1. when you see the moon, you are seeing the light from the sun reflected off it's surface. when you don't see the whole of the moon (sounds like a song. ) this is because of one of twon things. a. either the earth is casting a shadow on the moon because it is sitting partially between the moon and sun, or b. you are viewing the moon from the side relative to where the sun is shining on it.

matter of fact one never sees the whole of the Moon! From Earth due to libration, one sees at most 59 per cent of it! "there is no dark side of the Moon really. Matter of fact its all dark" Sounds like a song ). great gig in the sky.

2. the moon goes round the earth and the earth goes round the sun in the opposite direction, but not at the same speed, so sometimes you see more of the moon than others because it is at different phases of it's rotational cycle relative to the earth and sun, sometimes in front of the earth, sometimes behind, or anywhere in between.

I am not sure what you mean here but the Earth and Moon are to me more like a twin planet. they rotate about Each other! granted the centre of mass is within the Earth but the sense is the same for the Earth Moon and the the direction of travel of the centre of mass around the Sun i.e. they all travel in "the same way" and not in "the opposite direction". I mean looking from the "north pole" of the sun ( 90 degrees from the "ecliptic" "accertion disc" or "plane of Earth's orbit" as you see fit to define it) all planets go round the same way - anticlockwise as does the Earth-Moon and the rotation of the Earth. Otherwise how do you explain the Moon "catching up2 the Sun in the sky and passing the Sun out 13 times a year? If the Moon is going round the other way whay is it "getting ahead" of the Sun.

if i remember my brief lessons on the subject at school, the earth takes 24 hours to turn 360 degrees in a full circle,

In relation to what? Hence "sideral" "solar" etc. day

the moon takes 28 days (iirc) to go round the earth

again from phase to phase
or from fixed star to fixed star
or from node to node or apse to apse
all different "moonths"

and the earth takes 365 (and a quarter, again iirc) days to go round the sun.

again "solar" and "siderial" come into it.
the whole thing is important because one should understand how we can come to an accurate calendar. If not how can the farmers manage to feed us? Think of the children!