slyvester63 said:
Hi everyone, what do you think of the answer for this?
1. If the Earth's gravity has been pulling on the moon for billion years. explain why the moon has not already fallen down and crashed onto earth?
Whether it has been orbiting for billions of years is open for discussion. The actual age of the universe is debated by two sides to be either billions of years or just several thousand years.
Anyway, Wikipedia seems to indicate that the orbit or the moon is slightly increasing each year, not decreasing. Not finding anything specific (in albeit a short search) I can only suggest the following reasons:
- There are other gravity factors affecting the moon, e.g. the sun, that stop it falling in to the Earth.
- The Earth and Moon whip each other around in a cosmic gravity dance.
- We are still to understand more about space/time and gravity.
2. Explain why a total eclipse of the Sun is a very rare event at any one place on Earth?
The diameter of the moon is almost exactly the same as that of the sun (at their current realtive distances from the Earth). Although, because the moon seems to be moving away from Earth, the diameter of the moon is becoming less than the Sun and so we are seeing more Annular Eclipses.
Anyway, the solar eclipse can only happen once a month when there is a new moon and only then when the moon, sun and earth all line up exactly. If the moon does not line up with Earth at all, then the Eclipse shadow will be lost in space. (There has been an eclipse at one of the poles.) The moon does not travel around the Earth on exactly the same path, passing between the sun and Earth in exactly the same place each month. And a Solar eclipse will only happen, obviously, on the side of the Earth facing the sun at that exact time.
Hope that all helps get a discussion going, at least.
