On This Day, July 20: Apollo 11 Moon Landing

Aside from the Sun, the Moon was the most mysterious and influential object in the sky. It was more than a celestial object who illuminated the nights; it was the inspiration for many gods and myths, it guided calendars and its predictable cycles symbolized time, change, birth and death, and fertility. For nearly all of history, idea that a human being would ever set foot on the moon seemed beyond imagination. But history has shown as that as scientific knowledge advances the boundaries of what is possible continue to expand.

Buzz Aldren walking on the moon in a photograph taken by Neil Armstrong
Buzz Aldren walking on the moon in a photograph taken by Neil Armstrong

On July 20, 1969, the Apollo 11 mission achieved the impossible, landing the first humans on the Moons surface in one of the most remarkable accomplishments in human history. The journey to the Moon took the team of Neil Armstrong, Buzz Aldrin, and Michael Collins three days. As they entered the moon’s orbit, Neil Armstrong and Buzz Aldrin guided the Lunar Module Eagle down towards the moon, while Michael Collins stayed in orbit in the Command Module Columbia. The Eagle landed in the Sea of Tranquility with the words “Houston, Tranquility Base here. The Eagle has landed.” A few hours later Neil Armstrong descended onto the lunar surface and spoke the famous words “One small step for man, one giant leap for mankind.”

The Apollo 11 mission represents one of the most remarkable scientific achievements in all of human history. It was the culmination of centuries of scientific discoveries – beginning with Newton’s Laws of motion and gravity to modern advancements in mathematics, physics, material science, computing, and rocket science. The Apollo 11 mission reminds us of what can be achieved through the remarkable power of the scientific method.

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On This Day, July 19: First GPS Transmission

For most of human history, navigation required using the stars, landmarks, or maps. Only recently did a breakthrough in satellite navigation, knows as the Global Positioning System (GPS), render those methods obsolete. Today’s GPS is a highly precise system for measuring both position and time that began with a series experimental missions, including the first successful GPS transmission on July 19,1977.

First GPS receiver station at Rockwell-Collins
First GPS receiver station at Rockwell-Collins

On that day, the Navigation Technology Satellite-2 (NTS-2), recently launched from Vandenburg Air Force Base on June 23, 1977, successfully transmitted the first GPS signal from space. It was received at a building of the Rockwell-Collins company in Cedar Rapids, Iowa. The successful test proved that highly accurate positioning could be achieved by combining precisely timed signals from multiple satellites. The satellites and technology were developed by the US Department of Defense for military operations. As with many technologies developed by the DoD, it gradually made its way into civilian use to transform everyday life.

The GPS system today contains a network of around 30 satellites orbiting roughly 12,500 miles above Earth. Each satellite continuously broadcasts its exact location and the precise time the signal was sent, using extremely accurate atomic clocks. A GPS receiver listens for signals from multiple satellites, and by measuring how long each signal takes to arrive, it calculates the distance. Using a mathematical process called triangulation, the receiver can determine the latitude, longitude and even the current time. The GPS system has become one of the most useful tools, demonstrating how fundamental discoveries in physics and engineering can reshape how the world moves.

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On This Day, July 18: Birth of John Glenn

When John Glenn was born on July 18, 1921, humanity had barely begun to master flight. The first manned flight had occurred less than two decades ago and a flight beyond Earth’s atmosphere must have seemed more like science fiction than science reality. But four decades later that would become reality for John Glenn.

John Glenn in 1962
John Glenn in 1962

On February 20, 1962, aboard the Friendship 7 spacecraft, Glenn circled the planet three times in a nearly five-hour mission to become the first American to orbit the Earth. His success came at a pivotal time for the United States, as the country was locked in a Cold War with the Soviet Union and was up to this point losing the space race. The Soviet Union had already launched the first satellite and the first human, Yuri Gagarin, into space. Glenn’s mission restored confidence in the US space program while marking a major milestone in space exploration. 

The mission represented more than national pride, however. The lessons learned from Glenn’s flight directly influenced the Gemini and Apollo programs, culminating in the Moon lading just seven years later. Throughout his life, Glenn continued to remain involved in space exploration. In 1988, at the age of 77, he returned to space aboard the Discovery, becoming the oldest person to fly in space. John Glenn’s legacy for space exploration is impactful, but it goes far beyond his three orbits of Earth. He famously described his view from space and stated, “you don’t see borders.” What he saw was one fragile planet shared by all humans and all other living creatures – and this valuable perspective might be his more important legacy of all.

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On This Day, July 17: Earliest Recorded Solar Eclipse

The Sun stood in constant awe and reverence in the ancient world. Nobody knew exactly what it was, but people knew it provided warmth and life to the living world. Because of this, people tracked the path of the Sun and often worshipped it as a god. So, imagine the reaction that would occur when the Sun vanished in the middle of the day.

On July 17, 709 BCE, court astronomers in in Qufu, capital of the ancient Chinese state of Lu, watched and recorded this exact event. It was recorded in the Spring and Autumn Annals (Chunqiu), with the line “the Sun was totally eclipsed”, marking the first recoding in human history of a solar eclipse. Without modern astronomy, ancient civilizations could not explain what they were witnessing. Across the world, eclipses were often interpreted as supernatural omens – warnings from the gods, signs of political upheaval, and so on. Recording these events must have seemed like a good idea.

A Total Solar Eclipse
A Total Solar Eclipse

Over centuries, Chinese, Babylonian, Greek, and later Islamic astronomers accumulated additional observations of eclipses. They began to notice that they were not random but occurred in predictable patterns. Today, astronomers can predict a solar eclipse centuries in advance with extraordinary precision. Using our understanding of gravity and orbital mechanics, we know exactly when the Moon’s shadow will cross Earth’s surface and where totality will occur down to the second.

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On This Day, July 16: Trinity Test

For thousands of years, humanity sought to understand the fundamental building blocks of matter. What began decades earlier as a quest to understand the nature of the atom culminated in one of the most consequential moments in history. On the morning of July 16, 1945, a brilliant flash illuminated the New Mexico desert as the Trinity Test became the first successful detonation of a nuclear weapon, ushering in the Atomic Age.

As with many new technologies, the path to a nuclear weapon began much earlier with discoveries that transformed our understanding of the atom. Scientists such as Henri Becquerel, Marie Currie, Ernest Rutherford, Niels Bohr, and many others gradually revealed that the atom was in fact not indivisible but consisted of other elementary particles. These particles are arranged in a complex structure that stores an enormous amount of energy, some of which can be released under the right conditions. 

Fearing that Nazi Germany would develop an atomic bomb first, the United States launched the Manhattan Project to develop its own atomic bomb. The Manhattan Project brought together many of the world’s leading scientists and engineers, and after a few years of intense secrecy, research, and construction, it culminated in the Trinity Test.

A mushroom could from the Trinity Test
A mushroom could from the Trinity Test

The explosion exceeded expectations. The mushroom could rose to 7 miles high in the sky, with temperatures from the blast exceeding the surface of the Sun. Although the Trinity Test marked the birth of the nuclear age, it also demonstrated the remarkable power of scientific inquiry. Some of the same discoveries that led to nuclear weapons also gave rise to nuclear energy, advanced imaging technologies, carbon dating, and a deeper, more complete understanding of the universe itself.

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On This Day, July 15: Rosetta Stone Discovered

The hieroglyphics covering ancient Egyptian monuments spoke a language that nobody could understand. That changed on July 15, 1799, when a fortuitous discovery gave scholars the key they had been searching for. While strengthening the defenses of Fort Julien near the town of Rosetta, French soldiers serving in Napoleon’s Egyptian campaign uncovered a carved stone that initially looked ordinary enough. Yet that artifact, a large black basalt slab called the Rosetta Stone, became they key to deciphering the lost language of Egyptian hieroglyphics.

The Rosetta Stone
The Rosetta Stone

The Rosetta Stone contained on it a decree written in three different languages: Greek, Demotic, and Egyptian Hieroglyphics. Since the Greek language was known and could be read, researchers suspected the stone might serve as a translation key for the mysterious hieroglyphs. For nearly 1,500 years, no one could read the language of the ancient Egyptians. Their temples, monuments, and tombs were covered with elaborate symbols, but their meaning had been lost after the decline of the ancient Egyptian civilization. Some people even believed hieroglyphs were merely symbolic or mystical images rather than a true written language.

The breakthrough came in 1822 when French scholar Jean-Francois Champollion demonstrated that hieroglyphs represented both sounds and ideas, eventually unlocking the principles of the ancient writing system. Few archaeological discoveries have had such a profound impact. For the first time ever, historians could read the words carved onto Egypt’s temples, obelisks, and royal tombs, opening a window into more than three millennia of human civilization.

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On This Day, July 14: Mariner 4 Mars Flyby

Few worlds have captured the human imagination like Mars. For thousands of years, it was little more than a red dot in the night sky. Even after the invention of the telescope, people wondered and debated what the Martian surface was like, and many wondered if life had existed on the planet. On July 14, 1965, a small 575-pound spaceship called Mariner 4 made the first successful flyby of Mars, revealing close up photos of the planet’s surface.

Mariner 4 spacecraft
Mariner 4 spacecraft
(Credit: NASA)

Mariner 4 traveled more than 325 million miles over eight months to reach Mars, eventually passing within about 6,100 miles of the planet. For decades, some people, including a few scientists, believed Mars might harbor vegetation or remnants of advanced civilizations. The 22 photos from Mariner 4 replaced that speculation with evidence.

The photographs revealed a heavily cratered landscape that more closely resembled the moon instead of a living world. While this was disappointing for those who had hoped to find signs of life, it was a triumph for science. For the first time, humans had explored the surface of another planet not through imagination or speculation, but through direct observation. It also showed that interplanetary exploration was possible, paving the way for future missions such as Mariner 9, the Viking landers, and Mars rovers.

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On This Day, July 13, Passing of August Kekule

During the mid-1800s, chemists knew the atomic composition of many organic compounds but struggled to understand their arrangement. Carbon in particular was present in an astonishing variety of substances but nobody could explain why. August Kukele, who passed away on July 13, 1896, helped solve this problem by proposing that carbons atoms could bond to one another to form long chains. This idea became a cornerstone of organic chemistry, leading to the rapid growth in knowledge in organic chemistry in the following century.

Portrait of August Kekule
Portrait of August Kekule

Kukele’s most famous contribution to organic chemistry came in 1865, when he proposed the molecule benzene consisted of six carbon atoms linked together in a ring. The nature of his discovery also contains one of the most famous anecdotes in the history of science. Kukele claimed, nearly 25 years after proposing the structure of benzene, that the idea came to him after a dream where a snake seized its own tail. He awoke with a revelation: what if the carbon atoms in benzene from a closed ring rather than an open chain?

Kekule’s work underpins much of today’s modern organic chemistry. His vision (or dream?) of carbon atoms linked into rings provided chemists with an entirely new framework for understanding the molecular world. Our plastics, medicines, agricultural chemicals, synthetic fibers and various other industrial materials all rely on principles that trace back to his insights.

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On this Day, July 12: First JWST Images

The James Webb Space Telescope, NASA’s successor to the Hubble Space Telescope and the world’s most powerful telescope, was launched on Christmas Day of 2021. For months, astronomers knew the telescope was working, but nobody outside a small group of scientists had seen what it was capable of. On July 12, 2022, the first full-color images from the James Webb Space Telescope (JWST) were finally released by NASA, to the delight of millions of people worldwide.

The images revealed stunning views of the Carina Nebula, the Southern Ring Nebula surrounding a dying star, Stephans Quintet of interacting galaxies, and the atmosphere of the exoplanet WASP-96b. The JWST observes the universe in infrared light, allowing it to penetrate clouds of cosmic dust, revealing parts of the universe that were previously invisible. Its primary mirror allows for more than six times the light collecting area than the Hubble telescope.

Southern Ring Nebula, taken from two different instruments from JWST
Southern Ring Nebula, taken from two different instruments from JWST
(Credit: NASA)

The JWST has to ability to transform our understanding of nearly every area of astronomy. It is currently being used to learn more about the formation of early galaxies and black holes, the birth of stars and planetary systems, and the atmospheres of distant worlds that may one day reveal life on another planet.

Another day, another discovery. Browse the On This Day Archive.

The Gap Between Jesus and the Gospels

The belief among many Christians is that the Gospels of the New Testament provide an accurate account of the life, ministry, and death of Jesus. But the dating of the actual writings of the four Gospels throws this idea into serious doubt.  The truth is the Gospels were written decades after the death of Jesus that contain historical elements embedded with mythical stories of his life.

Matthew, Mark, Luke, and John
Matthew, Mark, Luke, and John

The Gospel According to Mark

The Gospel of Mark is the earliest written Gospel, and the best estimate is it was written around 70 CE. There are several lines of evidence to suggest this date. To begin with, it contains knowledge of the destruction of the Temple in Jerusalem, which occurred in the summer of 70 CE. The Gospel of Mark represents an early church leadership structure with an under-developed theology compared to that found later Gospel writings. Jesus is primarily depicted as an apocalyptic prophet and a suffering Messiah rather than the fully divine Son of God who is one with the Father.

We also know it was written before Luke and Matthew because each copies a significant amount of their Gospel from Mark. Matthew reproduces roughly 90% of Mark’s verses, while Luke preserves about two-thirds of them. In many cases, the wording is virtually identical. If the three Gospels represented completely independent eyewitness accounts, we would expect them to describe many of the same events but in their own unique language. Instead, entire paragraphs appear nearly word for word. The simplest conclusion is that both authors had a copy of Mark before them and used it as one of their primary written sources. Based on the above evidence, the Gospel of Mark fits in nicely as the earliest written Gospel with a date of about 70 CE – a full 40 years after Jesus’s death.

The Gospel According to Matthew

It’s fairly simple to provide a hard upper and lower limit when dating the Gospel of Matthew. We know it is written after Mark, providing a lower limit of around 70 CE. Ignatius of Antioch seems to be familiar with this Gospel, providing an upper dating limit of around 100-110 CE. The consensus of modern scholars is around 80-90 CE. This places it as written roughly 50 to 60 years after Jesus’s death.

As with the Gospel of Mark, the Gospel of Matthew contains knowledge of the destruction of the Temple in Jerusalem. It represents a more advanced church structure and theology than the Gospel of Mark, adding emphasis on Jesus as a divine authority. Mark was also used as a primary source when writing Matthew.  Approximately 90% of Mark’s verses appear here, many times word for word. The only way to have large sections in word for word agreement is if it was copied. 

The Gospel According to Luke

The Gospel of Luke was written about the same time as the Gospel of Matthew. The lines of evidence used to date it are also similar to Matthew. It contains knowledge of the destruction of the Temple of Jerusalem, it uses Mark as a primary source, and it contains a similarly advanced church structure and theology. Luke also begins by acknowledging that “many have undertaken to compile an account” before him. Rather than claiming to be an eyewitness, the author describes gathering traditions and written sources into an orderly narrative.

The Gospel of Luke is universally acknowledged as written by the same author as the Acts of the Apostles. The Acts describes the rapid expansion of Christianity through the Roman Empire, leading to the conclusion that the two-volume work was composed around 80-90 CE.

The Gospel According to John

The Gospel of John was the latest Gospel to be included in the New Testament, written around 90-100 CE. John’s Gospel is markedly different from the previous three. It includes a far more developed theology, suggesting decades of theological reflection within the early Christian movement. Jesus openly declares his divine identity, a theme that was completely absent in the earliest Gospel of Mark. John also refers to Judaism as “the Jews”, reflecting a sharp distinction between the Jewish and Christian communities. During Jesus’s life and shortly after his death, this distinction did not exist as Jesus and his followers were considered a sect of Judaism. 

The Gospel also presents a highly developed understanding of Jesus as the eternal Logos (“Word”) who existed before creation. This philosophical language shows the influence of decades of theological development and interaction with the wider Greco-Roman world.

Conclusion

Taken together, the four Gospels show a clear historical progression. Mark is the earliest and simplest account. Matthew and Luke build upon Mark while expanding both the narrative and the organization of the early church. John represents an even later stage, presenting a far more developed theology and a Christian community that had become increasingly distinct from Judaism.

The chronological gap between Jesus’s death and the writing of the Gospels is significant. Mark was written roughly forty years later, Matthew and Luke about fifty to sixty years later, and John perhaps sixty to seventy years after the events it describes. During those decades, stories about Jesus circulated primarily through oral tradition before eventually being written down by anonymous authors.

None of this necessarily means that the Gospels contain no authentic historical memories. Ancient traditions often preserve elements of genuine events. However, it also does mean they should not be approached as contemporaneous eyewitness reports. Instead, they are theological narratives produced by later Christian communities for a Christian audience that sought to explain who Jesus was and what his life meant. Understanding when the Gospels were written is therefore essential for distinguishing between the historical Jesus and the beliefs that developed about him over the course of the first century.

Further ReadingMisquoting Jesus by Bart Ehrman, The Gnostic Gospels by Elaine Pagels