What is the closest distance between Mercury and Earth?

When Mercury is at its closest point to Earth, astronomers call this opposition (from the point of view of Mercury). This would happen when Mercury was at its furthest from the Sun, and Earth is at its closest. When this happens, Mercury and Earth would be separated by only 77 million km (48 million miles).

Their maximum distance occur when Earth is at its furthest point from the Sun, and Mercury is at its maximum on the other side of the Sun. The three objects then line up perfectly. At this point, Mercury and Earth can be 222 million km (138 million miles) apart.

Mercury's closest approach to Earth occurs when both planets are on the same side of the Sun, known as inferior conjunction. At this time, Mercury is placed in between our Sun and Earth, reducing the distance between the two planets to nearly 28.6 million miles (46.0 million km).