Category Archives: Fides et Ratio

Jan 6 – Rev. Gregor Mendel, OSA, (1822-1884), “Father of Modern Genetics”, Man of Science, Man of God


As a professional applied scientist and a man of faith, I often hear, even from fellow Catholics, “How can that be?”  I respond, “How can what be?”  “Faith & Science together…in the same person?…in the same mind?…How can that be?”  If they are a little educated, I will also get, “What about Galileo?”

There is no contradiction.  In all my professional training, almost all in public schools except for one master’s degree, and even then you could hardly tell that school was Catholic, as is the schizophrenia of “Catholic identity” in our (Catholic) higher ed, I have never encountered any scientific topic which contradicted my Catholic faith.  None.  In conjunction, in all my amateur study of the Catholic faith, I have never encountered any article of faith or doctrine which contradicted my scientific training.  None. Never. Ever.  Amen.

In fact, modern physics takes even the scientist’s breath away with awe.  Romans 11:33.

Dr. Stephen Hawking who recently appeared in the documentary Curiosity on the Discover Channel concluding, “God does not exist!”  It is embarrassing for all scientists, irregardless of specialty, with even the slightest training in the scientific method, when such a famous one of us reach’s a very public conclusion not based on science, but on bias and prejudice.  Not very scientific, doctor.  No, not very scientific, indeed.  I have since offered my services to the Discover Channel as an expert, especially if that is the level of science they care to offer.

Dr. Hawking’s conclusion was that God did not exist since nothing, including God, existed before the Big Bang, as first proposed by Msgr Georges LeMaitre.  The basis of Dr. Hawking’s conclusion is that nothing existed.  No matter or energy existed.  That fallaciously assumes God is matter or energy.  ?  Dr. Hawking, even a budding high school science student would not presume to assume the Almighty was relegated to the domain of matter or energy.  Convenient for a desired conclusion, but intellectually and scientifically bankrupt.

The Church has an expression for it:  Fides et Ratio = Faith and Reason.  There is no contradiction.  If one carefully studies the Galileo affair, one will quickly find both sides were answering a different question, how so many misunderstandings commence, and no one will defend Messr. Galileo’s tact.  Not even his daughter, Virginia, or by her religious name, Suor Maria Celeste, a cloistered nun of the San Mateo Convent, Arcetri, and some say his closest confidant and advisor, even scientifically.  She had his brains, no?  Messr. Galileo is especially untactful when he mocks in word and illustration as a simpleton and a fool the then pope, who up until the publishing of Galileo’s book had been his friend, benefactor, and supporter.  Not very politic, Messr. Galileo.  Not very politic.



“Pea hybrids form germinal and pollen cells that in their composition correspond in equal numbers to all the constant forms resulting from the combination of traits united through fertilization.”

Gregor Johann Mendel was born on July 22, 1822 to peasant parents in a small agrarian town in Czechoslovakia. During his childhood he worked as a gardener, and as a young man attended the Olmutz Philosophical Institute.  From 1840 to 1843, he studied practical and theoretical philosophy as well as physics at the University of Olomouc Faculty of Philosophy.  In 1843 he entered an Augustinian monastery in Brunn, Czechoslovakia. Soon afterward, his natural interest in science and specifically hereditary science led him to start experiments with the pea plant.  Mendel’s attraction for scientific research was based on his love of nature in general. He was not only interested in plants, but also in meteorology and theories of evolution. However, it is his work with the pea plant that changed the world of science forever.

His beautifully designed experiments with pea plants were the first to focus on the numerical relationships among traits appearing in the progeny of hybrids.  His interpretation for this phenomenon was that material and unchanging hereditary “elements” undergo segregation and independent assortment.  These elements are then passed on unchanged (except in arrangement) to offspring thus yielding a very large, but finite number of possible variations.

Mendel often wondered how plants obtained atypical characteristics. On one of his frequent walks around the monastery, he found an atypical variety of an ornamental plant. He took it and planted it next to the typical variety. He grew their progeny side by side to see if there would be any approximation of the traits passed on to the next generation. This experiment was “designed to support or to illustrate Lamarck’s views concerning the influence of environment upon plants.”  He found that the plants’ respective offspring retained the essential traits of the parents, and therefore were not influenced by the environment. This simple test gave birth to the idea of heredity.

Overshadowing the creative brilliance of Mendel’s work is the fact that it was virtually ignored for 34 years. Only after the dramatic rediscovery of Mendel’s work in 1900 (16 years after Mendel’s death) was he rightfully recognized as the founder of genetics.

Why Peas?

Pisum sativum

Mendel was well aware that there were certain preconditions that had to be carefully established before commencing investigations into the inheritance of characteristics. The parental plants must be known to possess constant and differentiating characteristics.  To establish this condition, Mendel took an entire year to test “true breeding” (non-hybrid) family lines, each having constant characteristics.   The experimental plants also needed to produce flowers that would be easy to protect against foreign pollen.  The special shape of the flower of the Leguminosae family, with their enclosed styles, drew his attention.  On trying several from this family, he finally selected the garden pea plant (Pisum sativum) as being most ideal for his needs.  Mendel also picked the common garden pea plant because it can be grown in large numbers and its reproduction can be manipulated.  As with many other flowering plants, pea plants have both male and female reproductive organs.  As a result, they can either self-pollinate themselves or cross-pollinate with other plants. In his experiments, Mendel was able to selectively cross-pollinate purebred plants with particular traits and observe the outcome over many generations.  This was the basis for his conclusions about the nature of genetic inheritance.

Mendel observed seven pea plant traits that are easily recognized in one of two forms:

1.        Flower color: purple or white

2.        Flower position: axial or terminal

3.        Stem length: long or short

4.        Seed shape: round or wrinkled

5.        Seen color: yellow or green

6.        Pod shape: inflated or constricted

7.        Pod color: yellow or green

Mendel’s Law of Segregation

Mendel’s hypothesis essentially has four parts. The first part or “law” states that, “Alternative versions of genes account for variations in inherited characters.” In a nutshell, this is the concept of alleles. Alleles are different versions of genes that impart the same characteristic.  For example, each pea plant has two genes that control pea texture.  There are also two possible textures (smooth and wrinkled) and thus two different genes for texture.

The second law states that, “For each character trait (ie: height, color, texture etc.) an organism inherits two genes, one from each parent.”  This statement alludes to the fact that when somatic cells are produced from two gametes, one allele comes from the mother, one from the father. These alleles may be the same (true-breeding organisms), or different (hybrids).

The third law, in relation to the second, declares that, “If the two alleles differ, then one, the dominant allele, is fully expressed in the organism’s appearance; the other, the recessive allele, has no noticeable effect on the organism’s appearance.”

The fourth law states that, “The two genes for each character segregate during gamete production.”   This is the last part of Mendel’s generalization. This references meiosis when the chromosome count is changed from the diploid number to the haploid number. The genes are sorted into separate gametes, ensuring variation.  This sorting process depends on genetic “recombination.”  During this time, genes mix and match in a random and yet very specific way.  Genes for each trait only trade with genes of the same trait on the opposing strand of DNA so that all the traits are covered in the resulting offspring.  For example, color genes do not trade off with genes for texture.  Color genes only trade off with color genes from the opposing allelic sight as do texture genes and all other genes.  The result is that each gamete that is produced by the parent is uniquely different as far as the traits that it codes for from every other gamete that is produced.  For many creatures, this available statistical variation is so huge that in all probability, no two identical offspring will ever be produced even given trillions of years of time.

So, since a pea plant carries two genes, it can have both of its genes be the same.  Both genes could be “smooth” genes or they could both be “wrinkled” genes.  If both genes are the same, the resulting pea will of course be consistent.  However, what if the genes are different or “hybrid”?  One gene will then have “dominance” over the other “recessive” gene.  The dominant trait will then be expressed.  For example, if the smooth gene (A) is the dominant gene and the wrinkle gene (a) is the recessive gene, a plant with the “Aa” genotype will produce smooth peas.  Only an “aa” plant will produce wrinkled peas.  For instance, the pea flowers are either purple or white.  Intermediate colors do not appear in the offspring of these cross-pollinated plants.

The observation that there are inheritable traits that do not show up in intermediate forms was critically important because the leading theory in biology at the time was that inherited traits blend from generation to generation (Charles Darwin and most other cutting-edge scientists in the 19th century accepted this “blending theory.”).  Of course there are exceptions to this general rule.  Some genes are now known to be “incompletely dominant.”  In this situation, the “dominant gene has incomplete expression in the resulting phenotype causing a “mixed” phenotype.  For example, some plants have “incomplete dominant” color genes such as white and red flower genes.  A hybrid of this type of plant will produce pink flowers.  Other genes are known to be “co-dominant” where both alleles are equally expressed in the phenotype.  An example of co-dominant alleles is human blood typing.  If a person has both “A” and “B” genes, they will have an “AB” blood type.  Some traits are inherited through the combination of many genes acting together to produce a certain effect.  This type of inheritance is called “polygenetic.”  Examples of polygenetic inheritance are human height, skin color, and body form.  In all of these cases however, the genes (alleles) themselves remain unchanged.  They are transmitted from parent to offspring through a process of random genetic recombination that can be calculated statistically.  For example, the odds of a dominant trait being expressed over a recessive trait in a two-gene allelic system where both parents are hybrids are 3:1.  If only one parent is a hybrid and the other parent has both dominant alleles, then 100% of the offspring will express the dominant trait.  If one parent has both recessive alleles and the other parent is a hybrid, then the offspring will have a phenotypic ratio of 1:1.

Mendel’s Law of Independent Assortment

The most important principle of Mendel’s Law of Independent Assortment is that the emergence of one trait will not affect the emergence of another. For example, a pea plant’s inheritance of the ability to produce purple flowers instead of white ones does not make it more likely that it would also inherit the ability to produce yellow peas in contrast to green ones.  Mendel’s findings allowed other scientists to simplify the emergence of traits to mathematical probability (While mixing one trait always resulted in a 3:1 ratio between dominant and recessive phenotypes, his experiments with two traits showed 9:3:3:1 ratios).

Mendel was so successful largely thanks to his careful and nonpassionate use of the scientific method. Also, his choice of peas as a subject for his experiments was quite fortunate.  Peas have a relatively simple genetic structure and Mendel could always be in control of the plants’ breeding. When Mendel wanted to cross-pollinate a pea plant he needed only to remove the immature stamens of the plant. In this way he was always sure of each plants’ parents. Mendel made certain to start his experiments only with true breeding plants. He also only measured absolute characteristics such as color, shape, and texture of the offspring. His data was expressed numerically and subjected to statistical analysis. This method of data reporting and the large sampling size he used gave credibility to his data. He also had the foresight to look through several successive generations of his pea plants and record their variations. Without his careful attention to procedure and detail, Mendel’s work could not have had the same impact that it has made on the world of genetics.

Some of the “greatest minds”? of our generation comment on the importance of science education for our youth.
Hey, how ‘bout that Internet thing?  Not bad, huh?  🙂

Scientifically yours,  Happy New Year!

Apr 3 – Servant of God Jerome Lejeune, (1926-1994), Doctor of Down’s Syndrome


Letter to Cardinal George of Chicago:


Dear Cardinal George,

Hello, my name is Amy Goggin and I am a parishioner at St. John Fisher in Chicago. I’m writing this letter to you to ask for your support and guidance in a cause that has been on my heart recently. I have an on-line store. I make rosaries and religious jewelry. I have wanted to make a chaplet/bracelet for people afflicted with Down’s syndrome. While researching the patron Saint for these individuals, I realized that there is no patron Saint for them. I am wondering how to go about declaring one? How does the Church declare a patron saint?

I understand that there are patron saints for people with mental illnesses and people that are handicapped in one form or another but, there needs to be a specific advocate in heaven for the growing number of people afflicted with Down’s syndrome. Prenatal screening and diagnostic testing is most often used to identify unborn babies with Down’s syndrome and then that information is used to encourage an abortion. This testing does not provide information that could be used to treat the baby before birth. One out of every 800 pregnancies is diagnosed with having a Down’s baby.

That is about 400,000 in the US alone. Out of those, 84% to 91% are aborted in the US. If a mother decides to have her Down’s syndrome child there are many medical complications that are awaiting the child throughout his/her life. There seems to be a cultural war against these innocent human beings right from the start. Due to the large number of people with this condition and the life-threatening situation they find themselves, we as Catholics need an advocate in Heaven to offer up our prayers of both petition and thanksgiving.

While researching a saint that would be appropriate for this cause, I found Servant of God (whose cause for canonization was opened in 2007): Dr. Jerome Lejeune. He was a French Doctor that spent his life trying to find a cure for Down’s syndrome and fighting for an awareness of the sanctity of their lives. He discovered the cause of Down’s syndrome in 1958.

Dr. Lejeune worked closely with Pope John Paul II and was appointed the first president of the Pontifical Academy for Life. He treated around 5,000 patients. He would explain to new mothers that their child’s name was (child’s name) and he/she is not a disease, but a person that happens to have a disease. His mission was to have others understand the dignity that these individuals possessed, by looking beyond their condition to see a human being. His own daughter, Clara Lejeune Gaymard wrote a memoir titled Life is a Blessing about her father .

I believe that due to the nature of Dr. Lejeune’s life’s work, he is the perfect patron saint for people afflicted with this genetic condition. I’m wondering if you can help us with three things by your guidance and blessing. My friends and I are willing to do whatever we have to do, we just need some direction and support. We want to know how to officially request that the Church declare Lejeune the patron saint for people afflicted with Down’s syndrome.

We want to know how to create a chaplet of prayers for his intercession. Finally, there is a strong local support to have a national shrine on the South Side of Chicago for Catholics to come and pray for Lejeune’s intercession for their loved ones with Down’s syndrome. We believe that because of the large population of individuals with this condition on the South Side of Chicago, this would be the most appropriate place for such a shrine. We are willing to take on any logistical legwork necessary to further this cause. I would appreciate any help you can offer my friends and I with this endeavor and look forward to hearing back from you soon.”



Jerome Lejeune was born in Montrouge, France, in 1926. A reading of The Country Doctor by the French novelist Balzac convinced him of his vocation when he was 13 years old. He too wanted to be a simple country doctor dedicating his life to helping the poor.

After attending medical school, he was persuaded by Professor Raymond Turpin to collaborate with him on a study of Down syndrome. He accepted this challenge and his dreams of being a simple country doctor were laid to rest.

He and his wife Birthe had five children and his family life and his faith were always his priority. When his beloved father was dying of lung cancer, he recognised more deeply the mystery of human suffering and the presence of Christ in all those who suffer.

In 1954, he was appointed a committee member of the French Genetics society and in 1957 was named an expert on the effects of atomic radiation on human genetics by the United Nations.

In 1959 he discovered the cause of Down syndrome and was also to diagnose the first case of Cri du Chat Syndrome. In 1962, he was awarded the prestigious Kennedy prize and, in 1965, he was appointed to the first Chair in Fundamental Genetics at the University of Paris. During this time, he helped thousands of parents to accept and love their children with Down syndrome.

-quote of Dr. Jerome Lejeune, MD, in a letter to his wife after his acceptance speech in 1969 when he was given the William Allen Memorial Award, the highest distinction that could be granted to a Geneticist, in which he strenuously condemned abortion.

In 1991, he wrote a summary of his reflections on medical ethics for his fellow Catholics in seven brief points:

1. Christians, be not afraid. It is you who possess the truth. Not that you invented it but because you are the vehicle for it. To all doctors, you must repeat: “you must conquer the illness, not attack the patient.”
2. We are made in the image of God. For this reason alone all human beings must be respected.
3. Abortion and infanticide are unspeakable crimes.
4. Objective morality exists. It is clear and it is universal – because it is Catholic.
5. The child is not disposable and marriage is indissoluble.
6. “You shall honour your father and mother.” Therefore, uniparental reproduction by any means is always wrong.
7. In so-called pluralistic societies, they shout it down our throats: “You Christians do not have the right to impose your morality on others.” Well, I tell you, not only do you have the right to try to incorporate your morality in the law but it is your democratic duty.

There is a famous story of an American physician who told Lejeune the following:

“My father was a Jewish physician in Braunau, Austria. One day only two babies were born at the local hospital. The parents of the healthy boy were proud and happy. The other was a girl (with Down syndrome) and her parents were sad.”

The physician ended the story by saying that the girl grew up to look after her mother despite her own disability. Her name is not known. The boy’s name was Adolph Hitler. Quite likely the story is apocryphal. However, it does express the truth that was central to Lejeune’s vocation: people with disabilities are certainly no less human than those without.

In 1993, Pope Saint John Paul II, his close friend, appointed Lejeune to be the first president of the Pontifical Academy for Life. That same year he was diagnosed with lung cancer and, by Good Friday of 1994, he was critically ill. “I have never betrayed my faith” he said. While reflecting on his patients, he was moved to tears and said: “I was supposed to have cured them…What will happen to them?”

A little later he was filled with joy. He said: “My children, if I can leave you with one message, this is the most important of all: We are in the hands of God. I have experienced this numbers of times.” He died the next day. Pope Saint John Paul II wrote of him: “We find ourselves today faced with the death of a great Christian of the twentieth century, a man for whom the defense of life had become an apostolate.” His cause for canonization has been postulated. Our bishops have recently agreed on three priorities for the Church, one of which is to proclaim the coming of the Kingdom by supporting integrity in public life, cohesion and mutual respect in society and serving the marginalized and the vulnerable. May this great servant of God, an apostle of the vulnerable, be an example to us all.

Prayer to Obtain Graces by God’s Servant’s Intercession

God, who created man in your image and intended him to share your glory, we thank you for having granted to your Church the gift of professor & doctor, Jerome Lejeune, MD, a distinguished Servant of Life. He knew how to place his immense intelligence and deep faith at the service of the defense of human life, especially unborn life, always seeking to treat and to cure.

A passionate witness to truth and charity, he knew how to reconcile faith and reason in the sight of today’s world. By his intercession, and according to Your will, we ask You to grant us the graces we implore, hoping that he will soon become one of your saints.


Servant of God, Servant of Life!!!! Dr. Jerome Lejeune, MD, pray for us!!!!


Jun 20 – Msgr Georges LeMaitre, (1894-1966), Priest, Physicist, Father of the “Big Bang” Theory

Not a saint, yet, but a personal and professional hero of mine.


Monsignor Georges Henri Joseph Édouard Lemaître (July 17, 1894 – June 20, 1966) was a Belgian Roman Catholic priest, honorary prelate, professor of physics and astronomer at the Catholic University of Leuven.

Lemaître proposed what became known as the Big Bang theory of the origin of the Universe, which he called his ‘hypothesis of the primeval atom’.

Lemaitre was a pioneer in applying Einstein’s theory of general relativity to cosmology. He introduced the theoretical Hubble’s law in 1927 as a generic phenomena in relativistic cosmology. In 1931, he published his primeval atom theory in Nature. At the time, Einstein had expressed skepticism about Lemaître’s 1927 paper.

But it is Lemaître’s theory that changed the course of science.  Lemaître worked with astronomers and designed his theory to explain the observed redshift of galaxies, have testable implications, the linear relation beween distances and velocities, and to be in accord with observations of the time.

Lemaître proposed his theory at an opportune time, since Edwin Hubble would soon publish his velocity-distance relation that strongly supported an expanding universe and, consequently, the Big Bang theory. In fact, Lemaître’s 1927 paper derived what became known as Hubble’s Law, two years before Hubble did so, and provided an estimate of the numerical value of the constant. However, the data used by Lemaitre do not allow him to prove that there was an actual linear relation, a result achieved by Hubble.

Because Lemaître spent his entire career in Europe, his contributions are not as well known in the United States (USA) as those of Hubble or Einstein, men well known in the USA by virtue of residing there.

Lemaître recognized expanding solutions within relativistic cosmologies. Lemaître is the first one to propose that the expansion is the explanation for the redshift of galaxies. He further concluded that an initial “creation-like” event must have occurred.

Einstein at first dismissed, privately, Lemaître out of hand, saying that not all mathematics leads to correct theories. After Hubble’s discovery was published, Einstein quickly and publicly endorsed Lemaître’s theory, helping both the theory and its proposer get fast recognition.


In 1933, Lemaître found an important inhomogeneous solution of Einstein’s field equations describing a spherical dust cloud, the Lemaitre-Tolman metric.

At the end of his life, he was devoted more and more to numerical calculation. He was in fact a remarkable algebraicist and arithmetical calculator. Since 1930, he used the most powerful calculating machines of the time like the Mercedes. In 1958, he introduced at the University a Burroughs E 101, the University’s first electronic computer. Lemaître kept a strong interest in the development of computers and, even more, in the problems of language and programming. This interest grew with age until it absorbed him almost completely.

In 1951 Pope Pius XII took the position that the scientific theory of the Big Bang confirmed the biblical creation story. This apparently caused great embarrassment, even to horror, for Lemaitre, who met with the Pope very soon after to caution the Holy Father on drawing parallels between a scientific theory and the book of Genesis.  The Pope appointed LeMaitre to the Pontifical Academy of the Sciences.  John XXIII made him its president.

Georges LeMaitre, after having received numerous scientific awards in the latter part of his career for his work, died on June 20, 1966, shortly after having learned of the discovery of cosmic microwave background radiation, which provided further evidence for his intuitions about the birth of the Universe.

“We can compare space-time to an open, conic cup…The bottom of the cup is the origin of atomic disintegration; it is the first instant at the bottom of space-time, the now which has no yesterday because, yesterday, there was no space.”
-Msgr Georges LeMaitre, The Primeval Atom


Technically yours, 🙂

Roman Catholic cleric-scientists/engineers

Even I was blown away by this list.   Who knew?  Apparently, Wikipedia and its generous contributors!  Wikipedia, et al, gratias!  And just think, this does not include laity-scientist/engineers!  Fides et ratio!  Deo gratias!  Amen.

  • José de Acosta (1539–1600) – Jesuit missionary and naturalist who wrote one of the very first detailed and realistic descriptions of the new world
  • François d’Aguilon (1567–1617) – Belgian Jesuit mathematician, physicist, and architect.
  • Albert of Saxony (philosopher) (c. 1320–1390) – German bishop known for his contributions to logic and physics; with Buridan he helped develop the theory that was a precursor to the modern theory of inertia
  • Albertus Magnus (c. 1206–1280) – “One of the most famous precursors of modern science in the High Middles Ages.”[6] Patron saint of natural sciences; Works in physics, logic, metaphysics, biology, and psychology.
  • José María Algué (1856–1930) – Meteorologist who invented the barocyclonometer
  • José Antonio de Alzate y Ramírez (1737–1799) – Scientist, historian, cartographer, meteorologist; wrote more than thirty treatises on a variety of scientific subjects
  • Francesco Castracane degli Antelminelli (1817–1899) – Botanist who was one of the first to introduce microphotography into the study of biology
  • Giovanni Antonelli (1818–1872) – Director of the Ximenian Observatory of Florence; collaborated on the design of a prototype of the internal combustion engine
  • Nicolò Arrighetti (1709–1767) – Wrote treatises on light, heat, and electricity.
  • Giuseppe Asclepi (1706–1776) – Astronomer and physician; director of the Collegio Romano observatory; The lunar crater Asclepi is named after him.
  • Roger Bacon (c. 1214–1294) – Significant contributions to mathematics and optics; forerunner of modern scientific method.
  • Bernardino Baldi (1533–1617) – Mathematician and writer
  • Eugenio Barsanti (1821–1864) – Possible inventor of the internal combustion engine
  • Bartholomeus Amicus (1562–1649) – Wrote on philosophy, mathematics, astronomy, and the concept of vacuum and its relationship with God.
  • Daniello Bartoli (1608–1685) – Bartoli and fellow Jesuit astronomer Niccolò Zucchi are credited as probably having been the first to see the equatorial belts on the planet Jupiter
  • Joseph Bayma (1816–1892) – Known for work in stereochemistry and mathematics
  • Giacopo Belgrado (1704–1789) – Experimental works in physics, professor of mathematics and physics, and court mathematician
  • Mario Bettinus (1582–1657) – Jesuit philosopher, mathematician and astronomer; lunar crater Bettinus named after him
  • Giuseppe Biancani (1566–1624) – Jesuit astronomer, mathematician, and selenographer, after whom the crater Blancanus on the Moon is named
  • Jacques de Billy (1602–1679) – Produced a number of results in number theory which have been named after him; published several astronomical tables; The crater Billy on the Moon is named after him.
  • Paolo Boccone (1633–1704) – Cistercian botanist who contributed to the fields of medicine and toxicology
  • Bernard Bolzano (1781–1848) – Mathematician and logician; other interests included metaphysics, ideas, sensation, and truth.
  • Anselmus de Boodt (1550–1632) – One of the founders of mineralogy
  • Theodoric Borgognoni (1205–1298) – Medieval Surgeon who made important contributions to antiseptic practice and anaesthetics
  • Christopher Borrus (1583–1632) – Mathematician and astronomy who made observations on the magnetic variation of the compass
  • Roger Joseph Boscovich (1711–1787) – formulation of modern atomic theory, important contributions to astronomy
  • Joachim Bouvet (1656–1730) – Jesuit sinologist and cartographer who did his work in China
  • Michał Boym (c. 1612–1659) – One of the first westerners to travel within the Chinese mainland, and the author of numerous works on Asian fauna, flora and geography.
  • Thomas Bradwardine (c. 1290–1349) – Mathematician who contributed to mean speed theorem; one of the Oxford Calculators
  • Henri Breuil (1877–1961) – Archaeologist, anthropologist, ethnologist and geologist.
  • Jan Brożek (1585–1652) – Polish polymath, mathematician, astronomer, and physician; the most prominent Polish mathematician of the 17th century
  • Louis-Ovide Brunet (1826–1876) – One of the founding fathers of Canadian botany
  • Francesco Faà di Bruno (c. 1825–1888) – Mathematician beatified by Pope John Paul II
  • Giordano Bruno (1548–1600) – Dominican philosopher, mathematician, and astronomer who believed in the infinity of the universe; burned at the stake for other heretical views.
  • Ismaël Bullialdus (1605–1694) – Astronomer and member of the Royal Society; the Bullialdus crater is named in his honor
  • Jean Buridan (c. 1300 – after 1358) – Early ideas of momentum and inertial motion; sowed the seeds of the Copernican revolution in Europe
  • Niccolò Cabeo (1586–1650) – Jesuit mathematician; the crater Cabeus is named in his honor
  • Nicholas Callan (1799–1846) – Best known for his work on the induction coil
  • Jean Baptiste Carnoy (1836–1899) – Founder of the science of cytology
  • Giovanni di Casali (died c. 1375) – Provided a graphical analysis of the motion of accelerated bodies
  • Paolo Casati (1617–1707) – Jesuit mathematician who wrote on astronomy and vacuums; The crater Casatus on the Moon is named after him.
  • Laurent Cassegrain (1629–1693) – Probable namesake of the Cassegrain telescope; The crater Cassegrain on the Moon is named after him
  • Benedetto Castelli (1578–1643) – Benedictine mathematician; long-time friend and supporter of Galileo Galilei, who was his teacher; wrote an important work on fluids in motion
  • Bonaventura Cavalieri (1598–1647) – He is known for his work on the problems of optics and motion, work on the precursors of infinitesimal calculus, and the introduction of logarithms to Italy. Cavalieri’s principle in geometry partially anticipated integral calculus; the lunar crater Cavalerius is named in his honor
  • Antonio José Cavanilles (1745–1804) – A leading Spanish taxonomic botanist of the 18th century
  • Francesco Cetti (1726–1778) – Jesuit zoologist and mathematician
  • Tommaso Ceva (1648–1737) – Jesuit mathematician and professor who wrote treatises on geometry, gravity, and arithmetic
  • Christopher Clavius (1538–1612) – Respected Jesuit Astronomer and mathematician who headed the commission that yielded the Gregorian calendar; wrote influential astronomical textbook.
  • Guy Consolmagno (1952– ) – Jesuit astronomer and planetary scientist
  • Nicolaus Copernicus (1473–1543) –Renaissance astronomer famous for his heliocentric cosmology that set in motion the Copernican Revolution
  • Vincenzo Coronelli (1650–1718) – Franciscan cosmographer, cartographer, encyclopedist, and globe-maker
  • George Coyne (1933– ) – Jesuit astronomer and former director of the Vatican Observatory
  • James Cullen (mathematician) (1867–1933) – Jesuit mathematician who published what is now known as Cullen numbers in number theory
  • James Curley (astronomer) (1796–1889) – First director of Georgetown Observatory; determined the latitude and longitude of Washington D.C.
  • Albert Curtz (1600–1671) – Jesuit astronomer who expanded on the works of Tycho Brahe and contributed to early understanding of the moon; The crater Curtius on the Moon is named after him.
  • Johann Baptist Cysat (1587–1657) – Jesuit mathematician and astronomer, after whom the lunar crater Cysatus is named; published the first printed European book concerning Japan; one of the first to make use of the newly developed telescope; most important work was on comets
  • Jean-Baptiste Chappe d’Auteroche (1722-1769) – Astronomer best known for his observations of the transits of Venus
  • Ignazio Danti (1536–1586) – Dominican mathematician, astronomer, cosmographer, and cartographer
  • Armand David (1826–1900) – Zoologist and botanist who did important work in both areas in China
  • Charles-Michel de l’Épée (1712–1789) – Known as the “father of the deaf” and established the world’s first free school for the deaf
  • Francesco Denza (1834–1894) – Meteorologist, astronomer, and director of Vatican Observatory
  • Václav Prokop Diviš (1698–1765) – Studied the lightning rod independent of Franklin; constructed the first electrified musical instrument in history
  • Johann Dzierzon (1811–1906) – Pioneering apiarist who discovered the phenomenon of parthenogenesis among bees, and designed the first successful movable-frame beehive; has been described as the “father of modern apiculture”
  • Honoré Fabri (1607–1688) – Jesuit mathematician and physicist
  • Jean-Charles de la Faille (1597–1652) – Jesuit mathematician who determined the center of gravity of the sector of a circle for the first time
  • Gabriele Falloppio (1523–1562) – One of the most important anatomists and physicians of the sixteenth century. The Fallopian tubes, which extend from the uterus to the ovaries, are named for him.
  • Gyula Fényi (1845–1927) – Jesuit astronomer and director of the Haynald Observatory; noted for his observations of the sun; The crater Fényi on the Moon is named after him
  • Louis Feuillée (1660–1732) – Explorer, astronomer, geographer, and botanist
  • Placidus Fixlmillner (1721–1791) – Benedictine priest and one of the first astronomers to compute the orbit of Uranus
  • Paolo Frisi (1728–1784) – Mathematician and astronomer who did significant work in hydraulics
  • José Gabriel Funes (1963– ) – Jesuit astronomer and current director of the Vatican Observatory
  • Joseph Galien (1699 – c. 1762) – Dominican professor who wrote on aeronautics, hailstorms, and airships
  • Jean Gallois (1632–1707) – French scholar and member of Academie des sciences
  • Pierre Gassendi (1592–1655) – French astronomer and mathematician who published the first data on the transit of Mercury; best known intellectual project attempted to reconcile Epicurean atomism with Christianity
  • Agostino Gemelli (1878–1959) – Franciscan physician and psychologist; founded Catholic University of the Sacred Heart in Milan
  • Johannes von Gmunden (c. 1380–1442) – Mathematician and astronomer who compiled astronomical tables; Asteroid 15955 Johannesgmunden named in his honor
  • Carlos de Sigüenza y Góngora (1645–1700) – Polymath, mathematician, astronomer, and cartographer; drew the first map of all of New Spain
  • Andrew Gordon (Benedictine) (1712–1751) – Benedictine monk, physicist, and inventor who made the first electric motor
  • Christoph Grienberger (1561–1636) – Jesuit astronomer after whom the crater Gruemberger on the Moon is named; verified Galileo’s discovery of Jupiter’s moons.
  • Francesco Maria Grimaldi (1618–1663) – Discovered the diffraction of light, and indeed coined the term “diffraction”; investigated the free fall of objects; built and used instruments to measure geological features on the moon
  • Robert Grosseteste (c. 1175 – 1253) – One of the most knowledgeable men of the Middle Ages; has been called “the first man to write down a complete set of steps for performing a scientific experiment.”[7]
  • Paul Guldin (1577–1643) – Jesuit mathematician and astronomer who discovered the Guldinus theorem to determine the surface and the volume of a solid of revolution
  • Bartolomeu de Gusmão (1685–1724) – Known for his early work on lighter-than-air airship design
  • Johann Georg Hagen (1847–1930) – Director of the Georgetown and Vatican Observatories; The crater Hagen on the Moon is named after him.
  • Nicholas Halma (1755–1828) – French mathematician and translator
  • Jean-Baptiste du Hamel (1624–1706) – French natural philosopher and secretary of the Academie Royale des Sciences
  • René Just Haüy (1743–1822) – Father of crystallography
  • Maximilian Hell (1720–1792) – Jesuit astronomer and director of the Vienna Observatory; the crater Hell on the Moon is named after him.
  • Michał Heller (1936– ) – Templeton Prize winner and prolific writer on numerous scientific topics
  • Lorenz Hengler (1806–1858) – Often credited as the inventor of the horizontal pendulum
  • Hermann of Reichenau (1013–1054) – Historian, music theorist, astronomer, and mathematician
  • Pierre Marie Heude (1836–1902) – Jesuit missionary and zoologist who studied the natural history of Eastern Asia
  • Franz von Paula Hladnik (1773–1844) – Botanist who discovered several new kinds of plants, and certain genera have been named after him
  • Giovanni Battista Hodierna (1597–1660) – Astronomer who catalogued nebulous objects and developed an early microscope
  • Victor-Alphonse Huard (1853–1929) – Naturalist, educator, writer, and promoter of the natural sciences
  • Maximus von Imhof (1758–1817) – German Augustinian physicist and director of the Munich Academy of Sciences
  • Giovanni Inghirami (1779–1851) – Italian astronomer; there is a valley on the moon named after him as well as a crater
  • François Jacquier (1711–1788) – Franciscan mathematician and physicist; at his death he was connected with nearly all the great scientific and literary societies of Europe
  • Stanley Jaki (1924–2009) – Benedictine priest and prolific writer who wrote on the relationship between science and theology
  • Ányos Jedlik (1800–1895) – Benedictine engineer, physicist, and inventor; considered by Hungarians and Slovaks to be the unsung father of the dynamo and electric motor
  • Georg Joseph Kamel (1661–1706) – Jesuit missionary and botanist who established the first pharmacy in the Philippines
  • Otto Kippes (1905–1994) – Acknowledged for his work in asteroid orbit calculations; the main belt asteroid 1780 Kippes was named in his honour
  • Athanasius Kircher (1602–1680) – The father of Egyptology; “Master of a hundred arts”; wrote an encyclopedia of China; one of the first people to observe microbes through a microscope
  • Wenceslas Pantaleon Kirwitzer (1588–1626) – Jesuit astronomer and missionary who published observations of comets
  • Jan Krzysztof Kluk (1739–1796) – Naturalist agronomist and entomologist who wrote a multi-volume work on Polish animal life
  • Sebastian Kneipp (1821–1897) – One of the founders of the Naturopathic medicine movement
  • Marian Wolfgang Koller (1792–1866) – Professor who wrote on astronomy, physics, and meteorology
  • Franz Xaver Kugler (1862–1929) – Jesuit chemist, mathematician, and Assyriologist who is most noted for his studies of cuneiform tablets and Babylonian astronomy
  • Nicolas Louis de Lacaille (1713-1762) – French astronomer noted for cataloguing stars, nebulous objects, and constellations
  • Eugene Lafont (1837–1908) – Jesuit physicist, astronomer, and founder of the first Scientific Society in India
  • Antoine de Laloubère (1600–1664) – The first mathematician to study the properties of the helix
  • Bernard Lamy (1640–1715) – Philosopher and mathematician who wrote on the parallelogram of forces
  • Pierre André Latreille (1762–1833) – Entomologist whose works describing insects assigned many of the insect taxa still in use today
  • Georges Lemaître (1894–1966) – Father of the Big Bang Theory
  • Thomas Linacre (c. 1460–1524) – Humanist translator and physician
  • Francis Line (1595–1675) – Magnetic clock and sundial maker who disagreed with some of the findings of Newton and Boyle
  • Juan Caramuel y Lobkowitz (1606–1682) – Prolific writer on a variety of scientific subjects; a earlier writer on probability
  • Jean Mabillon (1632–1707) – Benedictine monk and scholar, considered the founder of palaeography and diplomatics
  • James B. Macelwane (1883–1956) – “The best-known Jesuit seismologist” and “one of the most honored practicioners of the science of all time”; wrote the first textbook on seismology in America.
  • Paul McNally (1890–1955) – Jesuit astronomer and director of Georgetown Observatory; the crater McNally on the Moon is named after him.
  • Pierre Macq (1930– ) – Physicist who was awarded the Francqui Prize on Exact Sciences for his work on experimental nuclear physics
  • Manuel Magri (1851–1907) – Jesuit ethnographer, archaeologist and writer; one of Malta’s pioneers in archaeology
  • Emmanuel Maignan (1601–1676) – Physicist and professor of medicine who published works on gnomonics and perspective
  • Charles Malapert (1581–1630) – Jesuit writer, astronomer, and proponent of Aristotelian cosmology; also known for observations of sunpots and of the lunar surface, and the crater Malapert on the Moon is named after him
  • Nicolas Malebranche (1638–1715) – Philosopher who studied physics, optics, and the laws of motion; disseminated the ideas of Descartes and Leibniz
  • Marcin of Urzędów (c. 1500–1573) – Physician, pharmacist, and botanist
  • Joseph Maréchal (1878–1944) – Jesuit philosopher and psychologist
  • Marie-Victorin (1885–1944) – Botanist best known as the father of the Jardin botanique de Montréal
  • Edme Mariotte (c. 1620–1684) – Physicist who recognized Boyle’s Law and wrote about the nature of color
  • Francesco Maurolico (1494–1575) – Made contributions to the fields of geometry, optics, conics, mechanics, music, and astronomy; gave the first known proof by mathematical induction
  • Christian Mayer (astronomer) (1719–1783) – Jesuit astronomer most noted for pioneering the study of binary stars
  • Gregor Mendel (1822–1884) – Augustinian monk and father of genetics
  • Pietro Mengoli (1626–1686) – Mathematician who first posed the famous Basel Problem
  • Giuseppe Mercalli (1850–1914) – Volcanologist and director of the Vesuvius Observatory; best remembered today for his Mercalli scale for measuring earthquakes which is still in use
  • Marin Mersenne (1588–1648) – Philosopher, mathematician, and music theorist who is often referred to as the “father of acoustics”
  • Paul of Middelburg (1446–1534) – Wrote important works on the reform of the Calendar
  • Maciej Miechowita (1457–1523) – Wrote the first accurate geographical and ethnographical description of Eastern Europe; also wrote two medical treatises
  • François-Napoléon-Marie Moigno (1804–1884) – Jesuit physicist and mathematician; was an expositor of science and translator rather than an original investigator
  • Juan Ignacio Molina (1740–1829) – Jesuit naturalist, historian, botanist, ornithologist and geographer
  • Louis Moréri (1643–1680) – 17th century encyclopaedist
  • Théodore Moret (1602–1667) – Jesuit mathematician and author of the first mathematical dissertations ever defended in Prague; the lunar crater Moretus is named after him.
  • Landell de Moura (1861–1928) – Inventor who was the first to accomplish the transmission of the human voice by a wireless machine
  • Gabriel Mouton (1618–1694) – Mathematician, astronomer, and early proponent of the metric system
  • Jozef Murgaš (1864–1929) – Contributed to wireless telegraphy and help develop mobile communications and wireless transmission of information and human voice
  • José Celestino Mutis (1732–1808) – Botanist and mathematician who led the Royal Botanical Expedition of the New World
  • Jean François Niceron (1613–1646) – Mathematician who studied geometrical optics
  • Nicholas of Cusa (1401–1464) – Cardinal, philosopher, jurist, mathematician, and astronomer; one of the great geniuses and polymaths of the 15th century
  • Julius Nieuwland (1878–1936) – Holy Cross priest, known for his contributions to acetylene research and its use as the basis for one type of synthetic rubber, which eventually led to the invention of neoprene by DuPont
  • Jean-Antoine Nollet (1700–1770) – Physicist who discovered the phenomenon of osmosis in natural membranes.
  • Hugo Obermaier (1877–1946) – Distinguished prehistorian and anthropologist who is known for his work on the diffusion of mankind in Europe during the Ice Age, and in connection with north Spanish cave art
  • William of Ockham (c. 1288 – c. 1348) – Franciscan Scholastic who wrote significant works on logic, physics, and theology; known for Ockham’s Razor
  • Nicole Oresme (c. 1323–1382) – One of the most famous and influential philosophers of the later Middle Ages; economist, mathematician, physicist, astronomer, philosopher, theologian and Bishop of Lisieux, and competent translator; one of the most original thinkers of the 14th century
  • Barnaba Oriani (1752–1832) – Geodesist, astronomer and scientist; greatest achievement was his detailed research of the planet Uranus; known for Oriani’s theorem
  • Luca Pacioli (c. 1446–1517) – Often regarded as the Father of Accounting; published several works on mathematics
  • Ignace-Gaston Pardies (1636–1673) – Physicist known for his correspondence with Newton and Descartes
  • Franciscus Patricius (1529–1597) – Cosmic theorist, philosopher, and Renaissance scholar
  • John Peckham (1230–1292) – Archbishop of Canterbury and early practitioner of experimental science
  • Nicolas Claude Fabri de Peiresc (1580–1637) – Astromer who discovered the Orion Nebula; lunar crater Peirescius named in his honor
  • Stephen Joseph Perry (1833–1889) – Jesuit astronomer and Fellow of the Royal Society; made frequent observations of Jupiter’s satellites, of stellar occultations, of comets, of meteorites, of sun spots, and faculae
  • Giambattista Pianciani (1784–1862) – Jesuit mathematician and physicist
  • Giuseppe Piazzi (1746–1826) – Theatine mathematician and astronomer who discovered Ceres, today known as the largest member of the asteroid belt; also did important work cataloguing stars
  • Jean Picard (1620–1682) – First person to measure the size of the Earth to a reasonable degree of accuracy; also developed what became the standard method for measuring the right ascension of a celestial object; The PICARD mission, an orbiting solar observatory, is named in his honor
  • Edward Pigot (1858–1929) – Jesuit seismologist and astronomer
  • Alexandre Guy Pingré (1711–1796) – French astronomer and naval geographer; the crater Pingré on the Moon is named after him, as is the asteroid 12719 Pingré
  • Jean Baptiste François Pitra (1812–1889) – Bendedictine cardinal, archaeologist and theologian who noteworthy for his great archaeological discoveries
  • Charles Plumier (1646–1704) – Considered one of the most important botanical explorers of his time
  • Marcin Odlanicki Poczobutt (1728–1810) – Jesuit astronomer and mathematician; granted the title of the King’s Astronomer; the crater Poczobutt on the Moon is named after him.
  • Léon Abel Provancher (1820–1892) – Naturalist devoted to the study and description of the fauna and flora of Canada; his pioneer work won for him the appellation of the “Father of Natural History in Canada”
  • Louis Receveur (1757–1788) – Franciscan naturalist and astronomer; described as being as close as one could get to being an ecologist in the 18th century
  • Franz Reinzer (1661–1708) – Wrote an in-depth meteorological, astrological, and political compendium covering topics such as comets, meteors, lightning, winds, fossils, metals, bodies of water, and subterranean treasures and secrets of the earth
  • Louis Rendu (1789–1859) – Bishop who wrote an important book on the mechanisms of glacial motion; the Rendu Glacier, Alaska, U.S. and Mount Rendu, Antarctica are named for him
  • Vincenzo Riccati (1707–1775) – Italian mathematician and physicist
  • Matteo Ricci (1552–1610) – One of the founding fathers of the Jesuit China Mission; co-author of the first European-Chinese dictionary
  • Giovanni Battista Riccioli (1598–1671) – Astronomer who authored Almagestum novum, an influential encyclopedia of astronomy; The first person to measure the rate of acceleration of a freely falling body; created a selenograph with Father Grimaldi that now adorns the entrance at the National Air and Space Museum in Washington D.C.
  • Richard of Wallingford (1292-1336) – Renowned clockmaker and one of the initiators of Western Trigonometry
  • Johannes Ruysch (c. 1460–1533) – Explorer, cartographer, and astronomer who created the second oldest known printed representation of the New World
  • Giovanni Girolamo Saccheri (1667–1733) – Jesuit mathematician and geometer
  • Johannes de Sacrobosco (c. 1195 – c. 1256) – Irish monk and astronomer who wrote the authoritative medieval astronomy text Tractatus de Sphaera; his Algorismus was the first text to introduce Hindu-Arabic numerals and procedures into the European university curriculum; the lunar crater Sacrobosco is named after him
  • Gregoire de Saint-Vincent (1584–1667) – Jesuit mathematician who made important contributions to the study of the hyperbola
  • Alphonse Antonio de Sarasa (1618–1667) – Jesuit mathematician who contributed to the understanding of logarithms
  • Christoph Scheiner (c. 1573–1650) – Jesuit physicist, astronomer, and inventor of the pantograph; wrote on a wide range of scientific subjects
  • George Schoener (1864–1941) – Became known in the United States as the “Padre of the Roses” for his experiments in rose breeding
  • Gaspar Schott (1608–1666) – Jesuit physicist, astronomer, and natural philosopher who is most widely known for his works on hydraulic and mechanical instruments
  • Franz Paula von Schrank (1747–1835) – Botanist, entomologist, and prolific writer
  • Berthold Schwarz (c. 14th century) – Franciscan friar and reputed inventor of gunpowder and firearms
  • Anton Maria Schyrleus of Rheita (1604–1660) – Astronomer and optrician who built Kepler’s telescope
  • George Mary Searle (1839–1918) – Paulist astronomer and professor who discovered six galaxies
  • Angelo Secchi (1818–1878) – Pioneer in astronomical spectroscopy, and was one of the first scientists to state authoritatively that the Sun is a star
  • Alessandro Serpieri (1823–1885) – Astronomer and seismologist who studied shooting stars, and was the first to introduce the concept of the seismic radiant
  • Gerolamo Sersale (1584–1654) – Jesuit astronomer and selenographer; his map of the moon can be seen in the Naval Observatory of San Fernando; the lunar crater Sirsalis is named after him
  • Benedict Sestini (1816–1890) – Jesuit astronomer, mathematician and architect; studied sunspots and eclipses; wrote textbooks on a variety of mathematical subjects
  • René François Walter de Sluse (1622–1685) – Mathematician with a family of curves named after him
  • Lazzaro Spallanzani (1729–1799) – Biologist and physiologist who made important contributions to the experimental study of bodily functions, animal reproduction, and essentially discovered echolocation; his research of biogenesis paved the way for the investigations of Louis Pasteur
  • Valentin Stansel (1621–1705) – Jesuit astronomer who made important observations of comets
  • Johan Stein (1871–1951) – Jesuit astronomer and director of the Vatican Observatory, which he modernized and relocated to Castel Gandolfo; the crater Stein on the far side of the Moon is named after him
  • Nicolas Steno (1638–1686) – Often called the father of geography and stratigraphy (“Steno’s principles”); beatified by Pope John Paul II
  • Pope Sylvester II (c. 946–1003) – Prolific scholar who endorsed and promoted Arabic knowledge of arithmetic, mathematics, and astronomy in Europe, reintroducing the abacus and armillary sphere which had been lost to Europe since the end of the Greco-Roman era
  • Alexius Sylvius Polonus (1593 – c. 1653) – Jesuit astronomer who studied sunspots and published a work on calendariography
  • Ignacije Szentmartony (1718–1793) – Jesuit cartographer, mathematician, and astronomer who became a member of the expedition that worked on the rearrangement of the frontiers among colonies in South America
  • André Tacquet (1612–1660) – Jesuit mathematician whose work laid the groundwork for the eventual discovery of calculus
  • Pierre Teilhard de Chardin (1881–1955) – Jesuit paleontologist and geologist who took part in the discovery of Peking Man
  • Francesco Lana de Terzi (c. 1631–1687) – Referred to as the Father of Aeronautics for his pioneering efforts; also developed the idea that developed into Braille
  • Theodoric of Freiberg (c. 1250 – c. 1310) – Dominican theologian and physicist who gave the first correct geometrical analysis of the rainbow
  • Joseph Tiefenthaler (1710–1785) – One of the earliest European geographers to write about India
  • Giuseppe Toaldo (1719–1797) – Physicist who studied atmospheric electricity and did important work with lightning rods; the asteroid 23685 Toaldo is named for him.
  • José Torrubia (c. 1700–1768) – Linguist, scientist, collector of fossils and books, and writer on historical, political and religious subjects
  • Franz de Paula Triesnecker (1745–1817) – Jesuit astronomer and director of the Vienna Observatory; published a number of treatises on astronomy and geography; the crater Triesnecker on the Moon is named after him.
  • Basil Valentine (c. 15th century) – Alchemist whom author James J. Walsh calls the father of modern chemistry[8]
  • Luca Valerio (1552–1618) – Jesuit mathematician who developed ways to find volumes and centers of gravity of solid bodies
  • Pierre Varignon (1654–1722) – Mathematician whose principle contributions were to statics and mechanics; created a mechanical explanation of gravitation
  • Giovanni Battista Venturi (1746-1822) – Discovered the Venturi effect
  • Fausto Veranzio (c. 1551–1617) – Bishop, polymath, inventor, and lexicographer
  • Ferdinand Verbiest (1623–1688) – Jesuit astronomer and mathematician; designed what some claim to be the first ever self-propelled vehicle – many claim this as the world’s first automobile
  • Francesco de Vico (1805–1848) – Jesuit astronomer who discovered or co-discovered a number of comets; also made observations of Saturn and the gaps in its rings; the lunar crater De Vico and the asteroid 20103 de Vico are named after him
  • Vincent of Beauvais (c.1190–c.1264) – Wrote the most influential encyclopedia of the Middle Ages
  • János Vitéz (archbishop) (c.1405–1472) – Archbishop, astronomer, and mathematician
  • Martin Waldseemüller (c. 1470–1520) – German cartographer who, along with Matthias Ringmann, is credited with the first recorded usage of the word America
  • Godefroy Wendelin (1580–1667) – Astronomer who recognized that Kepler’s third law applied to the satellites of Jupiter; the lunar crate Vendelinus is named in his honor
  • Johannes Werner (1468–1522) – Mathematician, astronomer, and geographer
  • Witelo (c. 1230 – after 1280, before 1314) – Physicist, natural philosopher, and mathematician; lunar crater Vitello named in his honor; his Perspectiva powerfully influenced later scientists, in particular Johannes Kepler
  • Julian Tenison Woods (1832–1889) – Passionist geologist and mineralogist
  • Theodor Wulf (1868–1946) – Jesuit physicist who was one of the first experimenters to detect excess atmospheric radiation
  • Franz Xaver von Wulfen (1728-1805) – Jesuit botanist, mineralogist, and alpinist
  • John Zahm (1851–1921) – Holy Cross Priest and South American explorer
  • Giuseppe Zamboni (1776–1846) – Physicist who invented the Zamboni pile, an early electric battery similar to the Voltaic pile
  • Francesco Zantedeschi (1797–1873) – Among the first to recognize the marked absorption by the atmosphere of red, yellow, and green light; published papers on the production of electric currents in closed circuits by the approach and withdrawal of a magnet, thereby anticipating Michael Faraday’s classical experiments of 1831
  • Niccolò Zucchi (1586–1670) – Attempted to build a reflecting telescope in 1616; may have been the first to see the belts on the planet Jupiter; corresponded with Kepler
  • Giovanni Battista Zupi (c. 1590–1650) – Jesuit astronomer, mathematician, and first person to discover that the planet Mercury had orbital phases; the crater Zupus on the Moon is named after him