: I just learned that mercury is in fact the closest planet to the earth. What is this madness and since when?

Question

: I just learned that mercury is in fact the closest planet to the earth. What is this madness and since when?

In: 3690

Answer 1

Since the planets all go around the sun at different speeds, we have to consider all the locations of their orbit.

But to keep things simple, just consider 4 locations.

Earth is at 6 o’clock and the Sun is in the middle. When Venus and Mercury are also at 6 o’clock, Venus is of course closer to Earth.

But what happens when Venus and Mercury are on the far side of the sun at 12 o’clock? Mercury is closer to Earth and by the same amount!

Now let’s look at 3 o’clock and 9 o’clock. This is a little harder to imagine, but if you draw it you can see that Mercury is just a little bit closer to Earth than Venus is.

Average the distances for the four locations together and you find that on average Mercury is a bit closer to Earth than Venus is.