Strangely, âposhliâ (which means âletâs goâ or âletâs head outâ in Russian) is actually the past tense of the verb meaning âTo head off on foot.â In other words, âposhliâ literally means, âWe (or they) headed off on foot.â How can a word which is in the past tense indicate the desire to head off somewhere now?
The Hill sphere, or gravitational sphere of influence, of Earth is about 1.5 Gm or 1,500,000 km in radius. This is the maximum distance at which the Earth's gravitational influence is stronger than the more distant Sun and planets.
And in the era of modern astronomy, improvements in instrumentation, methodology, and the ability to see Earth from space have certainly helped. According to modern estimates, the surface area of the Earth is approximately 510 million square km (5.1 x 108 km2) or 196,900,000 square miles. Determining this was not only a matter of ascertaining Earthâs dimensions, but also its proper shape.