Mons Hadley

• 1. Introduction

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  Mons Hadley rises 4.5 kilometers above the lunar plain, a massif so vast its base stretches 25 kilometers across. It sits in the northern portion of the Montes Apenninus, the great mountain range arcing across the northern hemisphere of the Moon. A valley just to its southwest became one of the most carefully chosen destinations in the history of human spaceflight. And yet, for all its prominence, the mountain itself was never walked upon. The questions worth asking are: who does this mountain honor, why did Apollo 15 land in its shadow, and what does the landscape surrounding it tell us about the ancient lunar surface?

• 2. Apollo 15 and the Valley

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  The valley to the southwest of Mons Hadley served as the landing site for the Apollo 15 expedition. Immediately to the southwest of that same valley stands Mons Hadley Delta, designated with the Greek letter delta, a slightly smaller peak reaching about 3.5 kilometers above the valley floor. The astronauts visited Mons Hadley Delta directly, collecting samples from its slopes. Mons Hadley itself, the taller of the two peaks, was only photographed from the surface. No human footprint has ever touched it. To the west of both peaks runs Rima Hadley, a sinuous rille that carves its way across the landscape and shares its name with the mountain.

• 3. Rima Hadley's Path

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  Rima Hadley follows a course generally toward the northeast, bending in the direction of the Mons Hadley peak. Its center sits at selenographic coordinates 25.0 degrees North, 3.0 degrees East, and it spans a diameter of 80 kilometers. The rille begins at a crater called Bela, an elongated formation whose long axis is oriented to the northwest. Four small craters near the rille have been assigned official names by the International Astronomical Union: Bela, Carlos, Jomo, and Taizo. Those names draw from Hungarian, Spanish, African, and Japanese masculine naming traditions, respectively. One nearby crater, now called Joy, was previously known as Hadley A before the IAU renamed it in 1973.

• 4. John Hadley's Legacy

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  Mons Hadley, Mons Hadley Delta, and Rima Hadley all carry the name of the English mathematician John Hadley, who lived from 1682 to 1744. A satellite crater designated Hadley C sits at 25.5 degrees North, 2.8 degrees East, with a diameter of 6 kilometers. By convention, features like this satellite crater are placed on lunar maps with their identifying letter on the side of the crater midpoint closest to Mons Hadley itself. That naming convention means Hadley's identity is woven into the cartographic fabric of this entire region of the Moon.