why is that lunar and solar eclipse does not occur monthly?

Answer 1

Because the moon's orbit around the earth is tilted (about five degrees) with respect to the plane of the ecliptic. If the moon is either above or below the ecliptic plane, it cannot be in a straight line with the sun and earth. The intersection of the ecliptic plane and the moon's orbital plane defines a line called the line of nodes, and when this line is aligned sufficiently closely with the sun-earth line, the three bodies are close enough to being on the same line that an eclipse can occur.

Answer 2

The sun moves through the sky along a path called the ecliptic. If the moon followed the same path through the heavens, we'd have two eclipses every month.

(The sun apparently "moves," that is. We all know that the earth and moon revolve around the sun, but this is simpler to understand if you just look at their motions in the sky. Let me assure you that I am indeed a Copernican.)

The moon does not exactly follow the sun's path, however. Each time at it starts out from the sun at New Moon, the lunar track is slightly different from the month before, reaching as much as 5 degrees north or south of the sun's path. That's why we don't have an eclipse every month.

Still, each month, the moon must cross the sun's path twice, once going north and once heading south. If it does so at times other than Full Moon and New Moon, there can be no eclipse. When the moon crosses the sun's orbit at Full and New phases, we get at least two.

The moon is one-half a degree wide, a substantial block of celestial real estate considering that the band the moon sweeps out north and south of the sun is 5 degrees on either side. What this means is that twice every 354 days, the moon is guaranteed to be in the neighborhood of the sun at Full and New phase, so there will be eclipses.

If the moon scores a direct hit on the sun's path near the New phase, there will be an eclipse of the sun, either total or annular depending on how close the moon is to the earth. There will also be one or two partial eclipses of the moon, because two weeks before or afterward, the moon will still be close to or perhaps not quite in the eclipse zone.

If the direct hit comes at Full Moon, you see a total eclipse of the moon, with one or two small partial eclipses of the sun two weeks before or after.

Should the moon's crossing of the sun's path not occur exactly at Full or New moon, you'll get one each solar and lunar eclipse, but the eclipse of the sun will either be partial or only total at high latitudes. The lunar eclipse will be partial or a shallow total eclipse.

Answer 3

The path of the moon around the Earth is not perfect. It is not aligned with the Sun. If the Earth and the Moon had formed together out of the same dust cloud 3 billion years ago, then the Earth and the Moon would be spinning perfectly aligned with the Sun and there would be regular monthly eclipses. There would be no seasons either because the axis of the Earth would be perpendicular to its orbit around the sun.

But the Moon was formed by an accidental collision that Earth had with another planet or asteroid. The collision knocked the Earth over 23 degrees, giving us the seasons, and blasted about 1/80 of the Earth's mass into an Earth orbit, which came together to form the Moon. The orbit of the moon is not aligned with the Sun. The Moon's orbit takes it in front of the Sun at irregular times. Then we might see an eclipse if we are lucky.

Answer 4

Because the moon's orbit is inclined slightly with respect to the ecliptic plane - thus, for a lunar eclipse to occur, the moon must not only be full, but also in the part of its orbit that intersects the ecliptic plane, otherwise it will be "above" or "below" the Earth and will still be able to receive light from the sun. Similar logic applies to solar eclipses.

Answer 5

the eclipses are not a cycle that keep on happening monthly...they happen only when the conditions are suitable...like when the moon covers the sun,there is a solar eclipse...the moon and sun dont cross each other every month. an eclipse will happen only if they cross each other.

Answer 6

'rhsaunders' and 'Pascal' have the right of it. Also, since about 70% of the Earths surface is ocean, a lot of solar eclipses track across places where there are no people to observe them.


Doug

Answer 7

The Earth takes only one revolution a year.So,there is no eclipses mothly.

Answer 8

coz it just doesn't happen! the earth revolves around the sun for a period of one year bla bla bla and the story goes on, but it just doesn't happen!