Earth’s only natural satellite, the Moon, is by far the most romantic and inspiring celestial object in our Solar System. Since the beginning of time, adults and children indistinctively have been lifting their eyes to the sky to gaze at this magnificent celestial body in awe and amazedness.
For millennia, the Moon has sparked the imagination of writers and poets, including James Joyce (“What counsel has the hooded moon, Put in thy heart, my shyly sweet, Of Love in ancient plenilune, Glory and stars beneath his feet”) or Shakespeare (“th’inconstant moon, That monthly changes in her circled orb”) among many others.
In music, the Moon has captivated the spirit of great artists like The Rolling Stones (“Moon Is Up”), Pink Floyd (”The Dark Side Of the Moon”), The Beatles (“Mr Moonlight”) and The Police (“Walking on the Moon”). Neil Young, the author’s favourite, sings a tribute to his wife, picturing the couple dancing under the “Harvest Moon”, the closest full Moon to the autumn equinox.
And what better representation than art? For centuries, the Moon has played a central role on the canvas of great painters such as Michelangelo (“Creation of the Sun, Moon, and Plants”), Edvard Munch (“Moon Light”), Vincent Van Gogh (“White House at Night”) or Henri Rousseau (“La Encantadora de Serpientes”).
But our natural satellite is not only a muse for artists and poets. At an average distance of 384,400 km (238,855 miles), the Moon has a strong impact on our planet. It moderates Earth’s motion on its axis, which stabilises the climate thus making life possible and favouring agriculture. It also regulates the tides to a rhythm that certain species of crabs, worms and fishes follow for their reproduction.
Sadly, the Moon is constantly shifting away from us at a rate of approximately 3.8 cm (1.5 in) each year, similar to the rate at which our fingernails grow. But no fear, it will take billions of years before the effects become noticeable.
From Earth, we only see one face of the Moon. This phenomena is called “tidal locking“, and means that the Moon rotates on its own axis at the same rate that it orbits Earth thus showing us always the same face. A complete orbit around Earth takes 27 days but due to our motion and orbit around the Sun, from our perspective the Moon appears to orbit us every 29 days.
The surface of the Moon is marked by long-inactive volcanoes, impact craters, and lava flows. The areas of the surface that appear bright are called “Highlands” whereas the dark features are called “Marea” (from Latin “mare”: sea). The latter are impact basins that were filled with lava from the volcanoes between 4.2 and 1.5 billion years ago. Some of the Mareas are so marked that are clearly visible to the naked eye.
The surface temperature can reach peaks of approximately 130°C (265°F) when lit by the Sun, then dropping to -170°C ( -274°F) in darkness. Initial samples returned to Earth from the Apollo missions did not detect any signs of liquid water. In 2008, however, the Indian mission Chandrayaan-1 detected hydroxyl molecules spread across the lunar surface and concentrated at the poles.
Following missions went even further and proved that the surface presents high concentrations of ice water in the permanently shadowed regions of the lunar poles. Finally, in October 2020 NASA confirmed for the first time to have found water also on the sunlit surface of the Moon.
This discovery is of significant importance as it makes the Moon a little more hospitable and simplifies life for NASA’s scientists in view of the establishment of a stable colony on our satellite, but also for future missions such as the Artemis Program, which will land the next man and the first woman on the Moon by 2024.
Among other things, the mission will serve as an experiment before sending astronauts to Mars. As a great man once said: “That’s one small step for a man, one giant leap for mankind”.