blank occurs when the moon is in the first-and third-quarter pahses and the sun and the moon are at 90 angle?
467653
neap tide is the answer.\n\nExplaination. Since it is the effect of the moon and sun's gavity that causes tides, there are high tides closest and farthest away from the two of them. When they are lined up, spring tide occurs, resulting in the highest and lowest possible tides. However, when the sun, moon, and earth are at a 90 degree angle, the difference between high tide and low tide is the least(Because the effects of gravity are spread out). This is neap tide.\n\nPS. At neap tide there is still a visible distinction between the high and low tides. This is because the sun and moon's gravity and distance from Earth are not the same.
257842
First Quarter.  Full moon on 9 August.\n\n(Sorry, fell into the US/GB trap.  Read question as 3 Aug)
543648
Oh no, you've figured out my hoax!!! You busted me, you're right, its not round. Sorry, I get silly sometimes. If you are at a position when the moon passes directly perpendicular to you relative to the sun's position then you will see a perfect half lit moon. you can simulate this with a big right triangle by taking a golf ball or some other ball and placing it at the  90 degree corner and placing a flashlight at one of the other corners pointing directly at the ball. Now line up your sight from the third corner and you should see a perfect half lit ball. :)
840266
If you can see the moon from both points at the same time then the phase of the moon will be the same.\n\nIf however the moon is visible in Britain, but still below the horizon in Australia, then the phase will have very slightly changed by the time the moon rises in Australia.
940937
the light side of the moon move in front of the sun causing it to form the image you see that is know as the solar eclipse\n(since the dark side of the moon is facing you then it's clearly dark, and the sun's behind it so light shines around it)
536217
The Moon's mass is less but you're closer to the centre.   Gravity goes up as the square of your distance from the centre.
991387
The phases of the moon are due to the portion of the moon that is being iluminated by the sun. The phases vary according to the relative position of the moon, Earth and sun. The moon is always there but once a moths it becomes invivible, this phase is know as New moon (or Dark moon), it occurs when the Sun and the moon are on the same side; therefore the the "dark" side of the moon is facing Earth so it appears to be invicible.
410954
The Earth is round.\nObviously at lower latitudes you view the moon from a different angle than what you would at higher latitudes.\nSo that at the equater the moon when rising would look like a bowl from that angle in that phase.
11081
A full moon is simply fully visible.  Usually, the earth is between the sun and the moon to some degree.  The curved shadow on the moon is the shadow of the earth.  A full moon is when the moon is slightly to the side of the earth and the sun is shinging on the entire surface with no shadow of the earth on it.\n\nSee the link below for a good explanation.
16015
Draw a big circle to represent the sun.\n\nDraw a medium circle to represent the earth.\n\nNow, between the two circles, draw a tiny circle to represent the moon.\n\nThe moon casts a shadow on the earth.  Imagine that you are in the shadow.  What you are seeing is an eclipse.  You only see the moon.\n\nWait a couple minutes and the moon will move away from the sun.  Now you can see both the sun and the moon.\n\nThe moon can continue moving away from the sun for a long time and you will still be able to see it.\n\nUsually, you can see the sun and moon at the same time because, most of the time, they are not on opposite sides of the earth.  An exception is when there is a full moon, or nearly full moon.  In that case, the sun and moon are on opposite sides of the earth and you can only see one at a time.
47586
A is correct, the moon muct be full, meaning the earth is between the sun and moon.\n\nThe other condition necessary is that the moon must be on the ecliptic.  The orbital path of the moon is tilted five degrees from the ecliptic, which is the plane that holds the orbit of the earth about the sun.  If the moon is above or beow the ecliptic, then the earth's shadow will miss it.  In the summer and the winter, there are two times when the moon crosses this ecliptic.  If there's a full moon in that time, then ther's a good clance of a lunar eclipse.  If there's a new moon in that time, there's a good chance of a solar eclipse.
236307
Phase 1 - New Moon - The side of the moon that is facing the Earth is not lit up by the sun. At this time the moon is not visible.  \n\nPhase 2 - Waxing Crescent - A small part (less than 1/2) of the moon is lit up at this point. The part that is lit up is slowly getting bigger. \n\nPhase 3 - First Quarter - One half of the moon is lit up by the sun at this point. The part that is lit up is slowly getting bigger. \n\nPhase 4 - Waxing Gibbous - At this time half of the moon is lit up. The part that is lit is slowly getting bigger. Waxing means to slowly get bigger. \n\nPhase 5 - Full Moon - The side of the moon that is lit up by the sun is facing the Earth. The entire moon is lit up at this point. \n\nPhase 6 - Waning Gibbous - The moon is not quite lit up all the way by sunlight. The part of the moon this is lit is slowly getting smaller. Waning means to slowly get smaller. \n\nPhase 7 - Last Quarter - Half of the moon is lit up but the sun. The part that we can see lit up is slowly getting smaller. \n\nPhase 8 - Waning Crescent - A small part of the moon is lit up at this point. It is getting smaller by the minute.
895142
full moon.  a lunar eclipse occurs when the earth blocks the light from the sun, so the earth is positioned between the sun and moon - the full moon phase.
581761
The moon, when passing between the Earth and the Sun, in the proper angle, temporarily blocks sunlight and thus causes the eclipse.\n\nMore info here: http://en.wikipedia.org/wiki/solar_eclipse
131420
For the month of April, the moon will begin as a new moon sliver on the first, progressing to the first quarter on the 6th.  The full moon occurs on the 15th, the last quarter on the 22nd and a new moon on the 29th.
837745
You know that when it's daytime for you, someone on the other side of Earth is experiencing night time - the Sun lights up half of the earth at any given time.  The same is true for the Moon - it is always half lit up by the Sun and half dark.  But we don't always see the lit up side.  Sometimes we do, like tonight (a Full Moon).  But other times we "see" the dark half (a New Moon) (you can't really see the dark half because it's dark!), and sometimes we see a little bit of both (First Quarter Moon, for example).  \n\nWe see different parts of the lit up side and the dark side because the Moon orbits Earth about once every month.  Right now, if you were to see the Sun, Earth, and Moon from high above Earth's north pole, the three would be almost lined up: Sun, then Earth, then Moon.  If they were *perfectly* lined up then there would be a lunar eclipse, but that only happens a couple times a year, if that.  Next week, as the Moon goes around Earth, the Sun, Earth, and Moon will make a right angle and not a straight line.  That's when we see a Third Quarter Moon - only the left half of the Moon will be visible as seen from Earth.  Another week and the Moon will be almost between the Sun and Earth, so the dark side of the Moon will be facing Earth - what we call New Moon.  (If the Moon came exactly between the Sun and Earth we would have a solar eclipse, but just like lunar eclipses they are very rare).\n\nThere is a huge difference between a lunar eclipse and a new moon - apparently several of the people who answered above me don't know that!
9375
While the Moon does rotate, it is tidally locked to the Earth.  This means that we always see the same side of the Moon.\n\nThis happens when two astronomical bodies closely orbit each other.