In the twilight hours of this evening, and for the following week, observers of the night sky will have the chance to witness an ethereal spectacle that has been dubbed the “Da Vinci glow.” This enigmatic light show, anticipated to occur around the period of the New Moon on May 19, is named in honor of the Italian genius who first decoded its cause over half a millennium ago.
Leonardo da Vinci, remembered primarily for his extraordinary contributions to art and science, is often associated with masterpieces such as the Mona Lisa and innovative designs that were far ahead of his time. Yet, in the realm of astronomy, he made a remarkable discovery that is less frequently acknowledged.
Da Vinci solved the puzzle of Earthshine, a celestial phenomenon that imparts a ghostly illumination to the Moon’s surface.
“When the Moon is a thin crescent, you can often see the dark part of the moon shining faintly. At first glance, this may seem quite mysterious as the crescent is the part of the Moon that is illuminated by the sun – so where does the light from the unilluminated part of the Moon come from? In fact, what we are seeing is light from the Earth being reflected back from the Moon! Hence the name Earthshine,” explained Professor Don Pollacco of the University of Warwick.
In essence, Earthshine results from the sun’s light reflecting off the Earth’s surface and then bouncing back off the Moon’s surface into our field of vision. Although this ghostly glow can usually be observed for several days before and after each New Moon, its visibility peaks during springtime at mid-northern latitudes. This increased visibility is due to the Moon’s position directly above the Sun at the time of its setting each evening.
However, Earthshine can become difficult to perceive as the Moon’s illumination intensifies. “As the Moon is more fully illuminated, its brightness increases hugely, and the faint Earthshine gets difficult to see,” explained Professor Pollacco.
NASA has recognized Leonardo da Vinci’s insightful understanding of the Earthshine phenomenon. The space agency stated: “When you think of Leonardo Da Vinci, you probably think of the Mona Lisa or 16th-century submarines or, maybe, a certain suspenseful novel. That’s old school. From now on, think of the Moon.”
“Little-known to most, one of Leonardo’s finest works is not a painting or an invention, but rather something from astronomy: He solved the ancient riddle of Earthshine.”
While Da Vinci was largely accurate in his understanding, he did make a few misinterpretations. He reportedly believed that Earth’s oceans were the main source of Earthshine, while modern scientific understanding suggests clouds and sea ice reflect the most light. Yet, these minor inaccuracies, which NASA refers to as “quibbles,” do not diminish the significance of da Vinci’s central discovery.
Given clear weather conditions, those eager to view the “Da Vinci glow” should look to the eastern sky from May 15 to May 17, before sunrise. As reported by LiveScience, the Moon will be at its lowest illumination of seven percent on Wednesday.
Following the New Moon, Earthshine can be observed in the western sky from May 21 to May 23, with the Moon’s illumination being around five per cent on Sunday.
In essence, the “Da Vinci glow” offers us a chance to connect with the past, appreciating not only the beauty of the cosmos but also the enduring impact of Leonardo da Vinci’s pioneering scientific inquiries.
The Moon, Earth’s only natural satellite, has been the subject of wonder, scientific study, and exploration for centuries. Despite our increasing understanding, there are still many aspects of the Moon that remain mysterious:
The most widely accepted theory about the Moon’s origin is the Giant Impact Hypothesis, also known as the Theia Impact. This theory suggests that a Mars-sized body named Theia collided with the early Earth around 4.5 billion years ago, and the debris from this impact eventually coalesced to form the Moon. However, this theory still has its complications and unanswered questions, such as the Moon’s isotopic composition being almost identical to Earth’s, which is an unexpected outcome of this hypothesis.
Just like Earth, the Moon experiences quakes. However, the source of these moonquakes is less clear. Some are likely caused by the gravitational interaction between the Earth and the Moon, but others seem to be linked to the cooling and contracting of the Moon’s interior, causing it to “crack” and create seismic activity.
The discovery of water ice in shadowed lunar craters by various lunar missions, including NASA’s LCROSS, has raised many questions about the source and extent of lunar water. Understanding how much water is on the Moon, where it’s located, and how it got there is crucial for future lunar exploration and potential human habitation.
The Moon’s far side (often incorrectly referred to as the “dark side”) is very different from the side that faces Earth. It has a thicker crust and is heavily cratered, with a scarcity of lunar maria (large, dark, basaltic plains). The reasons for these differences remain a topic of ongoing research.
For centuries, observers have reported short-lived changes in the appearance of the lunar surface. These events, known as Transient Lunar Phenomena (TLPs), include reports of unusual light patterns, color changes, or brief obscurations. The causes of TLPs are still not fully understood, with suggested explanations ranging from outgassing to impacts to electrostatic phenomena.
The Moon has a very weak magnetic field compared to Earth, but there are certain regions with localized magnetic fields much stronger than the average lunar field. These “magnetic anomalies” are still not fully understood, but some suggest they are remnants from an earlier period when the Moon had a global magnetic field.
These mysteries, and others, continue to make the Moon a fascinating object of study, as scientists strive to deepen our understanding of Earth’s celestial companion.
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