November 11, 1572

On this date, the Danish nobleman, astrologer, and alchemist Tycho Brahe observed (from Herrevad Abbey) a very bright star, now named SN 1572, that had unexpectedly appeared in the constellation Cassiopeia.  Since it had been maintained since antiquity that the world beyond the orbit of the moon, i.e., that of the fixed stars, was eternal and unchangeable (a fundamental axiom, known as celestial immutability, of the Aristotelian world view), other observers held that the phenomenon was something in the Earth’s atmosphere.  Tycho, however, noticed that the parallax of the object did not change from night to night, suggesting that the object was far away.  He argued that a nearby object should appear to shift its position with respect to the background.  Tycho published a small book, De Stella Nova (1573), thereby coining the term nova for a “new” star (we now know that Tycho’s star in Cassiopeia was a supernova 7500 light years from Earth).  He knew the cosmological ramifications of his discovery and was strongly critical of those who dismissed the implications of the astronomical appearance, writing in the preface to De Stella Nova: “O crassa ingenia. O caecos coeli spectatores” (“Oh thick wits.  Oh blind watchers of the sky”).

August 25, 1609 (a Tuesday)

On this date, the Italian mathematician Galileo Galilei marched the Doge of Venice (Leonardo Donato), his counsellor, the Chiefs of the Council of Ten, and the Sages of the Order, who commanded the Venetian navy, up the Bell Tower (Campanile) in St. Mark’s Square in Venice, Italy. Once at the top, Galileo showed them views of distant cities, ships on the horizon, and parishioners entering a church on the island of Murano – all of which had been invisible to the eye alone – with the aid of his first telescope. The Doge was awestruck. The military had a powerful new secret weapon. Venice was confirmed again as a triumph. Galileo presented the Doge with the telescope on his knees and received a doubled salary, a lifetime appointment, and a bonus amounting to a year’s wages.

Throughout the the rest of 1609, particularly during the winter, Galileo made many astronomical studies. On January 7, 1610 Galileo observed with his telescope what he described at the time as “three fixed stars, totally invisible by their smallness,” all close to Jupiter, and lying on a straight line through it. Observations on subsequent nights showed that the positions of these “stars” relative to Jupiter were changing in a way that would have been inexplicable if they had really been fixed stars. On January 10 Galileo noted that one of them had disappeared, an observation which he attributed to its being hidden behind Jupiter. Within a few days he concluded that they were orbiting Jupiter. He had discovered three of Jupiter’s four largest satellites (moons): Io, Europa, and Callisto. He discovered the fourth, Ganymede, on January 13. Galileo named the four satellites he had discovered Medicean stars, in honor of his future patron, Cosimo II de’ Medici, Grand Duke of Tuscany, and Cosimo’s three brothers. [Later astronomers, however, renamed them the Galilean satellites in honor of Galileo himself.] On March 12, 1610 Galileo published the results of his studies in a brief treatise entitled Sidereus Nuncius (Starry Messenger).

These observations over a six night period, from January 7 through January 13, provided a view to Galileo that revealed that perhaps not everything orbited the Earth (geocentric model), as Ptolemy as well as the Catholic Church had adopted. And, if these small, but bright points of light went around Jupiter and not the Earth, perhaps there were other objects that did not orbit the Earth. His findings allowed him to confirm the Sun-centered theory of Copernicus. This short period of time from the summer of 1609 through to March of 1610, when Siderius Nuncius was published, had a revolutionary impact on astronomy almost overnight and it catapulted Galileo into the scientific spotlight and into the fire and wrath of the Catholic Church.

The Catholic Church condemned Galileo for his theories on June 22, 1633. He was forced to disown them and to live on his own for the rest of his life. In the following century the Vatican began changing its attitude. A mausoleum was built in 1734 to honor him. In 1822 Pope Pius VII gave permission for Galileo’s theory to be taught in schools. In 1968 Pope Paul VI had the trial against Galileo reassessed, then Pope John Paul II took the final step in the Church’s rehabilitation of the scientist in 1984 when he formally acknowledged that the Catholic Church had erred when it condemned the Italian astronomer for maintaining that Earth revolved around the Sun.

June 22, 1633 (a Wednesday)

On this date, the Florentine-Italian astronomer Galileo Galilei was compelled by the Roman Inquisition to recant the theory he held that the earth travels around the sun.

May 18, 1910 (a Wednesday)

On this date, thousands of people took to their roofs, huddling for comfort and praying for salvation. Many believed the end of the world was near. The source of their anxiety was the return of Halley’s Comet from its 75-year odyssey through space.

Many scientists were excited by the opportunity to increase the knowledge of astronomy. By late 1909, several of the world’s major observatories had geared up for Halley’s appearance. The public, too, eagerly awaited the moment when the comet became visible to the naked eye. Scientists had calculated it would appear between May 18 and 19, predicting that Halley’s tail would possibly sweep across Earth.

The tabloids jumped in, and discussed the catastrophic effects of the gaseous comet on the Earth’s atmosphere, causing many to panic. Despite a number of previous documented appearances having caused no deaths, the 1910 return of Halley’s Comet was widely perceived as a threat to mankind, allegedly due to noxious vapors emanating from its tail. This may be the first apocalyptic panic founded on a scientific, rather than religious misapprehension. In actual fact, the tail of Halley’s Comet never came any closer than 400,000 km to the Earth’s surface, and would not have been harmful at any distance.

May 14, 1864 (a Saturday)

A fragment of the Orgueil meteorite.

On this date, a carbonaceous chondrite disintegrated and fell in fragments near the French town of Orgueil. One specimen was immediately examined by the French scientist S. Cloëz, who commented that its content “would seem to indicate the existence of organized substances in celestial bodies.” Subsequently, several eminent chemists of the time, including Gabriel-Auguste Dubrée and Marcellin Berthelot, analyzed samples and confirmed the existence of organic materials in the rock. However, hopes of discovering actual living matter in the meteorite were dashed by the experiments of Louis Pasteur, as recounted by Carl Sagan:

[He] caused a special drill to be constructed, which, he hoped, would remove samples from the interior of the meteorite without contaminating them with microorganisms from outside. Using sterile techniques, Pasteur inoculated an organic medium to search for growth of any indigenous microorganisms which the meteorite interior might contain. The results were negative, and have relevance today: Pasteur extracted his sample shortly after the fall of the meteorite, and was, of course, a very careful experimentalist.

A fragment of the Ivuna meteorite (Tanzania, Africa, 1938).

Virtually all meteorites scientists have studied are former parts of asteroids. However, recent determination of the amino acid signatures within the Orgueil meteorite and Ivuna meteorite suggest that these compounds were likely synthesized from components such as hydrogen cyanide, which have been recently observed in the comets Hale-Bopp and Hyakutake. This suggests that the organic material in Orgueil and Ivuna is the product of reactions that once took place in the nucleus of a comet, which, if true, would make these meteorites the first to be identified as having come from a cometary nucleus. This would add to the evidence that the amino acids that helped generate life on Earth may have been delivered by meteorites that were derived from the remnants of comets.

April 15, 1857 (a Wednesday)

On this date, a 3-kg carbonaceous chondrite fell at Kaba, near Debrecen, Hungary. The arrival of this meteorite was described as follows in the book The Geologist (1859) by Samuel Joseph Mackie (pp. 285-6):

About 10 pm an inhabitant of Kaba, sleeping in the open air, was awakened by a noise, different from that of thunder, as he described it, and perceived in the serene sky a luminous globe, of dazzling brightness, following a parabolic course during four seconds. This phenomenon was observed by several inhabitants of the same place. As one of them was riding out the next morning, his horse was frightened by the sight of a black stone, deeply bedded in the soil of the road, the ground around it being depressed and creviced. When dug out the meteorite weighed about 7 pounds. The finder broke off some fragments, and the remainder, weighing 5-1/4 lbs., was deposited in the Museum of the Reformed College at Debreczin.

Samples of the Kaba meteorite and the Cold Bokkeveld meteorite were examined and found to contain organic substances by Friedrich Wöhler, who inferred a biological origin. Ironically, it was Wöhler who had shown that it was possible to make organic chemicals by inorganic means. However, it was only later appreciated that complex carbon molecules can be manufactured in space by purely chemical processes.

April 15, 1452

On this date, Leonardo da Vinci was born at Anchiano near Vinci in the Florence area of Italy.

March 15, 1806 (a Saturday)

On this date, a 6-kg carbonaceous chondrite – a type of meteorite carrying carbon-based, organic chemicals – was unequivocally identified for the first time. Its arrival on Earth was noted at 5:30 pm, outside Alais, France. The organic chemicals it carried suggested the possibility of life on whatever body was the source, somewhere in the universe. According to the observations of the Swedish chemist Jöns Jakob Berzelius and a commission appointed by the French Academy of Sciences, it “emits a faint bituminous substance” when heated. Berzelius analyzed the Alais meteorite and reported in 1833 that destructive distillation yielded a blackish substance, indigenous water, carbon dioxide gas, a soluble salt containing ammonia, and a blackish-brown sublimate, which Berzelius confessed was unknown to him.

March 5, 1616 (a Saturday)

On this date, the Copernican theory was declared “false and erroneous” by the Decree of the Holy Congregation of the Most Illustrious Lord Cardinals in charge of the Index (more commonly known as the Decree of the Index) written by Cardinal Robert Bellarmine, and issued by the Catholic Church in Rome. Further, no person was to be permitted to hold or teach the theory that the Earth revolves around the sun. When Galileo subsequently violated the decree, he was put on trial and held under house arrest for the final eight years of his life.

February 17, 1600 (a Thursday)

The statue of Bruno in the place where he was executed.

On this date, the Italian philosopher and Dominican friar Giordano Bruno was brought to the Campo de’ Fiori, a central Roman market square. His tongue in a gag, tied to a pole naked, Bruno was burned at the stake as a heretic. This followed his lengthy imprisonment and trial that had begun on January 27, 1593 under the Roman Inquisition.

In his book De l’Infinito, Universo e Mondi (On the Infinite Universe and Worlds), which was published in 1584, Bruno argued that the universe was infinite, that it contained an infinite number of worlds, and that these are all inhabited by intelligent beings:

Innumerable suns exist; innumerable earths revolve around these suns in a manner similar to the way the seven planets revolve around our sun. Living beings inhabit these worlds.

In Cena de le Ceneri (The Ash Wednesday Supper), also published in 1584, Bruno defended the heliocentric theory of Copernicus, but it appears that he did not understand astronomy very well, for his theory is confused on several points.

In still another book published in 1584, De la Causa, Principio et Uno (On Cause, Prime Origin, and the One), Bruno seemed to anticipate Einstein’s theory of relativity when he wrote:

There is no absolute up or down, as Aristotle taught; no absolute position in space; but the position of a body is relative to that of other bodies. Everywhere there is incessant relative change in position throughout the universe, and the observer is always at the center of things.

Closeup of the statue of Bruno in the Campo de’ Fiori.

Some say that Bruno was executed because of his Copernicanism and his belief in the infinity of inhabited worlds, but it may have been for theological errors, such as denying the divinity of Christ. In fact, no one knows for certain the exact grounds on which he was declared a heretic because the volume or volumes of his Roman trial is missing from the Vatican archives. The only remaining record is a summary of the trial, rediscovered on November 15, 1940 and published in 1942. Some abstracts of Giordano Bruno’s works, his interrogations, some of the records of an earlier Venetian trial in 1592 against him, and some other documents copied from the original Roman trial converge in the summary, which was probably used by the Assessor of the Holy Office of that period. In this document, Bruno is quoted in one of the last interrogations by the judges of the Holy Office (maybe in April 1599) before his execution. He defended his theories as scientifically founded and by no means against the Holy Scriptures:

Firstly, I say that the theories on the movement of the earth and on the immobility of the firmament or sky are by me produced on a reasoned and sure basis, which doesn’t undermine the authority of the Holy Sciptures […]. With regard to the sun, I say that it doesn’t rise or set, nor do we see it rise or set, because, if the earth rotates on his axis, what do we mean by rising and setting[…].

On August 7, 1603, the Church placed all his works on the Index Librorum Prohibitorum (List of Forbidden Books). Four hundred years after his execution, official expression of “profound sorrow” and acknowledgement of error at Bruno’s condemnation to death was made during the papacy of John Paul II.

On March 2, 2008, a 6-meter-tall statue of an upside-down figure, evocative of flames, was unveiled in Berlin’s Potsdamer Platz station as a memorial to Giordano Bruno and as a new reminder of the value and cost of free thought [Science 319(5869): 1467 (14 March 2008)]. The sculpture is by Alexander Polzin. Ernst Salcher of the Giordano Bruno Foundation, which helped fund the project, said the sculpture is designed to “irritate” the viewer into reflecting on the role of human reason in making the world a better place.

February 15, 1564

On this date, the Florentine-Italian astronomer Galileo Galilei was born in Pisa, Italy. Galileo made a good discovery great. Upon hearing at age 40 that a Dutch optician had invented a glass that made distant objects appear larger, Galileo crafted his own telescope and turned it toward the sky. He quickly discovered that our Moon has craters, that Jupiter has its own moons, that the Sun has spots, and that Venus has phases like our Moon. Galileo, who lived to 1642, made many more discoveries. He claimed that his observations only made sense if all the planets revolved around the Sun, as championed by Aristarchus and Copernicus, and not around the Earth, as was commonly believed then. The powerful Roman Inquisition made Galileo publicly recant this conclusion, but today we know he was correct.

January 20, 1633

On this date, Galileo, at age 68, left his home in Florence, Italy to face the Inquisition in Rome. By June 22, 1633, he had buckled under the threats and interrogation by the Inquisition, and renounced his “belief” that the Earth revolved around the Sun.