2007-01-01 14:59:29 · 4 answers · asked by 420 1 in Science & Mathematics ➔ Astronomy & Space
The Moon's orbit around the Earth is not in the same plane as the Earth's orbit around the Sun. Therefore, when the Moon is closest to the Sun and between us and the Sun (New Moon), usually it will be above or below the Sun in the sky and won't obstruct it. Only when the Moon is passing through the Earth-Sun plane in its tilted orbit (an "ascending node"or a "descending node") do you get eclipses, and then you get lunar and solar eclipses together. This happens about every 174 days, or twice in 348 days, a period called the eclipse or anomalistic year. Since this is not quite a full tropical year, times of eclipses wander around the calendar, getting earlier and earlier every year.
2007-01-01 15:07:49 · answer #1 · answered by alnitaka 4 · 1⤊ 0⤋
Because the plane of the moon's orbit around the earth is not the same plane as that of the earth's orbit around the sun -- the two planes are inclined to each other by about five degrees. This means that most of the time the moon is not in the earth's orbital plane, which it would need to be in order for an eclipse to occur.
2007-01-01 15:03:01 · answer #2 · answered by Anonymous · 1⤊ 0⤋
because the moon does not orbit the earth on the exact plane of the earth's equator at all times. SOmetimes it's slightly above this plane, sometimes slightly below. When it lines up exactly, we have an eclipse.
2007-01-01 15:02:48 · answer #3 · answered by Joni DaNerd 6 · 1⤊ 0⤋
Because the orbits of the Moon, Sun and Earth are not in the same plane, but slightly inclined to each other.
I could explain this, but I thought that I would keep it short.
2007-01-01 15:04:06 · answer #4 · answered by Anonymous · 1⤊ 0⤋