Question

Why does not the earth falls into the sun?Explain.

Answer 1

The earth is constantly trying to fall into the sun, but it keeps missing. That is essentially what an orbit is. The sun exerts an attractive force on the earth, accelerating the earth directly towards the sun. This acceleration is constantly taking place. However, the earth also has some sideways momentum (perpendicular to the direction towards the sun). So as it falls towards the sun, it also moves to the side. As long as that sideways motion is enough to "side-step" the sun, the earth will orbit instead of crashing. You can see this more clearly in a more elliptical orbit:


The planet (green) appears to be falling towards the sun (blue), but it has just enough sideways momentum to miss the sun and swing around. The earth and moon have an amount of sideways motion so that the orbits are nearly circular. In other words, we are moving sideways fast enough to so that we maintain a nearly constant distance to the sun, despite constantly accelerating towards it

Answer 2

Because earth is a transparent sphere