Apollo 10's Lunar Module flies within 8.4 nautical miles (16 km) of the Moon's surface.

Apollo 10 was the fourth human spaceflight in the United States' Apollo program and the second to orbit the Moon. NASA, the mission's operator, described it as a "dress rehearsal" for the first Moon landing. It was designated an "F" mission, intended to test all spacecraft components and procedures short of actual descent and landing.

The Apollo Lunar Module, originally designated the Lunar Excursion Module (LEM), was the lunar lander spacecraft that was flown between lunar orbit and the Moon's surface during the United States' Apollo program. It was the first crewed spacecraft to operate exclusively in space, and remains the only crewed vehicle to land anywhere beyond Earth.

A nautical mile is a unit of length used in air, marine, and space navigation, and for the definition of territorial waters. Historically, it was defined as the meridian arc length corresponding to one minute of latitude at the equator, so that Earth's polar circumference is very near to 21,600 nautical miles. Today the international nautical mile is defined as exactly 1,852 metres. The derived unit of speed is the knot, one nautical mile per hour.

The Moon is Earth's only natural satellite. It orbits around Earth at an average distance of 384,399 kilometres (238,854 mi); about 30 times Earth's diameter. Its orbital period and its rotation period are synchronized at 29.5 days by Earth's gravity pulling on the Moon. This makes the Moon tidally locked to Earth, always facing it with the same side. The Moon's gravitational pull produces tidal forces on Earth, which are the main driver of Earth's tides.