Why isnt every full moon the same?

Answer 1

There are at least two reasons.

First, the moon's orbit around the earth is not perfectly circular but slightly elliptical, so it actually varies in distance from closest (perigee) to farthest (apogee) during its month-long cycle. The effect is subtle but perceptible.

Second, there are well-known subjective factors relating to human perception that alter its apparent size, even when the actual size is the same. For example, when the moon is near the horizon it always seems larger than when it is high in the sky, because we see it in relation to distant objects on the horizon. As it rises it seems more isolated and smaller in relation to the vastness of the sky.

Of course, these are essentially just theories and the true answer has yet to be found. ____________ You may be asking about the phases of the moon. During the course of the lunar month, we are watching one lunar day as it unfolds on the surface of the moon that we can observe. During the full moon it is lunar noontime at the center of the moon's face; at new moon it is lunar midnight at the same location. This lunar day (which is the same length as our lunar month) unfolds all over the moon, but again we only observe one face of the moon from our vantage point on earth.

Answer 2

They differ in what is called the Phase Angle (or, earth-object-sun angle). If you have ever seen a lunar eclipse, you might have noticed that the moon appears to be amazingly bright right before and right after the eclipse. If it is a clear night, it might even be described as dazzling. This is not because of some arcane or magical property of the eclipse. When you think about it, right before and after the eclipse you are seeing the most direct reflection possible of sunlight off of the moon's surface. Now, lunar eclipses don't happen every month. Ask yourself why not.

If the orbital plane of the moon around the earth and the orbital plane of the earth around the sun (this one is called the ecliptic) were co-planar (the very same plane) then lunar and solar eclipses would each happen every month. Sun earth and moon would form a straight line at New Moon (solar eclipse, Phase Angle at near to 180 degrees) and again at Full Moon (lunar eclipse, Phase Angle at or extremely near to zero degrees). Since the moon's orbital plane is not the same as the earth's orbital plane, then the earth's shadow will be at different distances from the moon at every full moon. Another way to say it is that the moon will come as close as it can to forming a straight line with the sun and earth, but will fall short of doing so, by differing degrees, unless there is an eclipse that month.

Now think about the Full Moon, and in your mind create the Phase Angle like this: imagine a line that goes from the center of the earth straight out to the center of the moon (the center of the moon will be the point of the angle) and then the line comes straight from the center of the moon to the center of the sun. For full moons that do not include a lunar eclipse that angle cannot and will not be zero. The earth is so much larger than the moon that even during a lunar eclipse the angle might not actually hit exactly and precisely zero. For non-eclipse full moons the angle will be different from month to month. During a solar eclipse the Phase Angle will be at or extremely near to 180 degrees.

Also, the apparent size of the full Moon depends the Moon's distance from Earth, in its elliptical orbit.

Answer 3

The Moon orbits the Earth approximately every 28 days and since some months have more than 28 days there can be 2 full moons. The second full moon in any given month is sometimes called a "blue moon".

Answer 4

because the moon sucks

Answer 5

It is not clear what you mean by not being the same. The astronomical process is the same each time