For an astronomy person.... Moon and Sun question........?

Question

On the days you can see the moon and the sun at the same time, Why is it sometimes the moon isn't full?

If the moon and the sun are above the horizon, then the Earth should not be able to cast a shadow on the moon from the sun's light? Shouldn't you see the full moon when you see the sun at the same time? If so, why is the moon not always full when you can see the sun also?

Thanks for your kind answers.

Answer 1

We get a full moon when the moon is on the opposite side of earth than the sun. So when we see the moon and sun together, we are closer to a new moon than a full moon.

The earth doesn't always cast a shadow on the moon (a lunar eclipse) because the moon, sun, and earth are only lined up twice a year. At the other times, the moon is slightly offset from it's orbit due to the way it orbits, which means it's just far enough away not to be eclipsed.

The earth's shadow doesn't cause phases of the moon. The moon is always half-lit from the sun and half-dark from pointing away from the sun. What part the earth sees varies as the moon goes around the earth. Sometimes we see half of the light side and half of the dark side (quarter moon).

Answer 2

You seem to think that the phases of the moon are caused by the Earth's shadow. They're not. The dark part of the moon is just the part of the moon where it's night - same as Earth, only half the moon can be illuminated at a time.

The moon is full when it's opposite the sun, so you never see the full moon and the sun in the sky at the same time.

Answer 3

Moon's phases are not caused by Earth's shadow! The origin of Moon's phases is in the spherical form of the Moon. The Sun illuminates only one half of the Moon's sphere. As the Moon travels around the Earth you can see the Moon only partially illuminated. For example, if you can see the Moon high in the sky during the sunset, only the "west" side of the Moon is illuminated (first quarter).
But you can see Earth's shadow on the Moon from time to time - during Lunar eclipses. The Earth is between Sun and Moon in this moment, so Lunar eclipses can be observed only during full moon.

Answer 4

The phases of the Moon are not caused by the Earth's shadow. Only eclipses of the Moon are caused by the Earth's shadow. The phases are caused by the fact that sunlight illuminates only one side of the Moon, be we are not always in a position to see all of the illuminated side.

Answer 5

There is no way to determine anything about a person's personality from this information. There is no way that astrology can tell you things about your own personality that you don't already know or believe. The positions of stars and planets in the sky have no effect whatsoever on human life or behavior.