## Wednesday, July 14, 2021

### Talking about distance of the Solar system

The average distance between the Earth and the Moon is 384,000 km. With some clarifications this distance is large enough to contain all the other seven planets of the Solar System!

The Moon orbits the Earth on an elliptical orbit: at the apogee the distance is 406 thousand km, while at the perigee it is 357 thousand km. However, these values ​​refer to the distance between the centers of the two bodies, while we are interested in the distance from surface to surface. It is therefore necessary to subtract the sum of the radii of the Moon and the Earth, equal to about 8100 km. The distance at the apogee becomes 398 thousand km, while that at the perigee of 348 thousand km.

By adding the average diameters of the seven planets, a value of about 393,000 km is obtained. However, we must consider that the planets are not perfectly spherical, but their polar diameter due to rotation is always less than the equatorial one. Considering the planets aligned along their polar axes, a value smaller than 393,000 km is obtained.

We see that this value is lower than the lunar apogee, but higher than the perigee. Consequently, it would be possible to insert all seven planets in the distance that separates the Earth from the Moon only when the latter is near the apogee.

Credit: BuzzFeed.