384,400. About four hundred thousand km (~240,000 mi) – is it near or far? Compared to the distances in our everyday life, its a lot but still, one has to go that far to reach our closest neighbor in the heavens. The average distance of the Moon from the Earth, it takes more than a second for a ray of light and at usually three days for a spacecraft to cover it. But how does the Moon orbit us exactly?
The Earth, the Moon and the distance between them, to scale.
Firstly, it obeys Kepler's laws of planetary motion: the orbital path is an ellipse around us, and it travels faster when closer and slower when farther. It usually comes as close as 362,570 km and goes out to 405,410 km – changing its actual distance by more than 10 per cent! But since we are not alone in the Solar System, these figures are subject to change, most prominently from the influence of the Sun.
One of the effects is the change in perigee and apogee distances (the closest and farthest points from the Earth). When extreme perigees and full Moons coincide, some use the therm “Supermoon”, just as it happened this March. So how extreme it was? Not so much, it turns out: with a perigee distance of 356,575 km, it deviated by ~6000 km or 1.5% from the average. As I said, it wasn't really much.
The difference between two full Moons, one at perigee, the other at apogee.
Read the complete story written by our László Molnár here.
Keine Kommentare:
Kommentar veröffentlichen