2007-01-21 14:20:47 · 7 answers · asked by heather g 1 in Science & Mathematics ➔ Astronomy & Space
Because the three bodies have to be in a straight line: sun....earth....moon.
That means we see the moon full face on; i.e. a full moon. If the moon is at some other phase, then the alignment isn't a straight line, but some angle, and so the earth's shadow goes by the moon.
HTH
Charles
2007-01-21 14:28:54 · answer #1 · answered by Charles 6 · 0⤊ 0⤋
A lunar eclipse happens when the sun, the earth, and the moon all line up, with the moon on the opposite side of the earth from the sun. In this way the moon is entirely in the earth's shadow, and therefore cannot be seen, as it generates no light itself. Now, if the earth is roughly between the moon and the sun (as is the case before a lunar eclipse), sunlight can reach the entire part of the near face of the moon -- hence a full moon.
In contrast, during a half moon, the line from the earth to the moon and the line from the sun to the moon are at right angles, which is why sunlight only reaches half of the near face of the moon, and we see a wedge. In this situation there's no way the moon can be in the earth's shadow.
2007-01-21 14:30:17 · answer #2 · answered by bobqwatson 2 · 0⤊ 0⤋
The eclipse happens because the Earth gets between the Moon and the Sun and casts a shadow on the Moon. So the side of the Moon that's facing us is also directly facing the Sun: a full Moon.
2007-01-21 14:29:23 · answer #3 · answered by injanier 7 · 0⤊ 0⤋
For there to be a lunar eclipse, the Sun, Earth and Moon must be in direct alignment in this order:
Sun--------Earth--------Moon
A lunar eclipse is where the Earth's shadow is cast on the Moon. This can only happen when the Moon is in the "full moon" position directly opposite the Sun and Earth.
EARTH/SPACE TEACHER
2007-01-21 14:27:30 · answer #4 · answered by CAROL P 4 · 2⤊ 0⤋
A lunar eclipse is just the fullest kind of full moon possible, so full in fact that our own shadow gets in the way.
Usually the full moon passes over or under the shadow, so no eclipse.
2007-01-21 15:14:47 · answer #5 · answered by anonymous 4 · 0⤊ 0⤋
Only when the moon is full can the earth pass between the moon and the sun so as to cast a shadow upon the moon.
2007-01-21 14:31:51 · answer #6 · answered by grassapelli 1 · 0⤊ 0⤋
Because that's the only time when the moon is on the opposite side of the earth as the sun. It's the only time when the moon is in the earth's shadow.
2007-01-21 14:30:32 · answer #7 · answered by Anonymous · 0⤊ 0⤋