Faith and Science in Astronomy Textbooks

On occasion someone will ask a member of the staff of the Vatican Observatory to recommend a good astronomy textbook, with “good” meaning not simply that the book effectively conveys astronomical concepts, but that it does not go out of its way to portray science and faith as being in conflict or to make its reader feel that science requires the rejection of religious faith.

The listing below attempts to provide a limited overview of various textbooks from a “Faith and Science” perspective. The listed books were reviewed for their discussions of two key figures in the history of astronomy: Johannes Kepler (1571-1630) and Galileo Galilei (1564-1642). How books treat Kepler and Galileo is used here to gauge their treatments of matters of faith and science.

For more discussion of why Johannes Kepler and Galileo Galilei, click here. This discussion will be useful when reading the reviews.

But in brief, if a textbook treats the subject of faith and science, it will likely discuss Galileo. A solid discussion of Galileo will not state that Church officials refused to accept his discoveries. It will not suggest that Galileo proved that the Earth circles the sun. It will not portray opposition to the idea that Earth moves as having been simply religious in nature. It will portray the debate over Earth’s motion, and Galileo’s interaction with Church officials, as complex.

In addition, if a textbook treats the subject of faith and science, some discussion of Kepler’s faith can indicate effort on the part of the author or authors to look seriously at the subject. Kepler is a key figure in astronomy. His faith was a strong part of who he was. He wrote his faith directly into his scientific writings. His faith-filled view of a universe that reflected its creator influenced his astronomical ideas. A good text should tell enough about Kepler’s faith to enable the reader to have some sense of what motivated his ideas about the universe. Without that, books end up giving the reader little more than a nebulous statement that Kepler somehow figured it out by looking at data.

A book that makes no mention of Kepler’s faith, but goes on at length about religious opposition to Galileo, is probably relaying an inaccurate picture of faith and science.

Note that the listings below are not recommendations. Most books contain some errors; to err is human. Within some of the books below are obvious errors, such as stating that Galileo’s observations were “the first fundamentally new astronomical data in 2000 years”, despite Tycho Brahe’s data (which preceded Galileo’s observations) being what Kepler used to develop his laws of planetary motion; or stating about Tycho Brahe’s model of a sun that circles Earth while planets circle the sun, that “few people took this model seriously”; or stating that Galileo’s Sidereus Nuncius was written in Italian; or stating that one of Kepler’s laws of motion appeared in his early work Mysterium Cosmographicum, which he wrote prior to working with Tycho Brahe, and thus before he obtained the data that he used to develop his laws of motion; or even promoting studies of UFOs. The listings below, which are in alphabetical order by the last name of each book’s first author, are only about the discussions of Kepler and Galileo found within each book. The rest of the book may be good or not.

Finally, the reader may wonder why so many of the books reviewed tend to be from the 1980’s-2000’s. This is because this project was made possible thanks to the discovery in 2020 of a large collection of textbooks assembled over time by Dr. Les D. Burton of Louisville, Kentucky, whose career teaching astronomy spanned that time period.


    1. Abell, George O.; Morrison, David; Wolff, Sidney C. 1991. Exploration of the Universe, 6th ed. Saunders College Publishing.
      Note: The authors of this book were particularly distinguished. At the time the book was published, Abell was known for his catalog of galaxy clusters, Morrison was Chief of the Space Sciences Division, NASA Ames Research Center, and Wolff was Director of the National Optical Astronomy Observatories. The authors had a personal interest in the history of astronomy, as photographs of various historical sites are credited to Abell and Morrison.
      Kepler: No mention of religion. The authors state that Kepler “discovered that the orbit could be fitted very well by a particular oval curve known as an ellipse [p. 35]” and “Kepler believed in an underlying harmony in nature, and he searched for numerological relations in the celestial realm [p. 36]”.
      Galileo: Four paragraphs, including mention of Pope St. John Paul II’s actions on Galileo. The book states that Galileo’s Dialogue is “a magnificent and unanswerable argument for Copernican astronomy”.
    2. Arny, Thomas T. 1994. Explorations: An Introduction to Astronomy. Mosby.
      Kepler: No mention of Kepler’s faith. The book notes that Kepler’s laws were a “major breakthrough”. It states that “it is perhaps ironic that such mathematical laws should come from Kepler because so much of his work is tinged with mysticism [p. 47]”.
      Galileo: Half of a paragraph on Galileo and the Church (p. 49), noting that “the Pope was actually a friend of Galileo”, that “Galileo escaped lightly”, and “only in 1992 did the Catholic Church admit it had erred in condemning Galileo for his ideas”.
    3. Arny, Thomas T. 2006. Explorations: An Introduction to Astronomy, 4th ed. McGraw Hill Higher Education.
      Kepler: Discussion is essentially identical to that in Arny’s 1994 book (above). Same terms are used.
      Galileo: Again, discussion is identical to that found in Arny’s 1994 book.
    4. Bennett, Jeffrey; Donahue, Megan; Schneider, Nicholas; Voit, Mark. 2002. The Cosmic Perspective, 2nd ed. Addison Wesley.
      Kepler: The authors state that “Kepler was deeply religious and believed that understanding the geometry of the heavens would bring him closer to God [p. 135]”. The book has no specific discussion of how he arrived at the idea of elliptical orbits.
      Galileo: The book has a lengthy discussion of Galileo’s work (p. 137-139) that contains no mention of his interactions with the Church. However, there are brief mentions in two other places. The longer of these is in part of a section (p. 34) on the “Human Adventure of Astronomy”, as an example of the impact astronomy can have on society. Here the authors write that Galileo was “put under house arrest in 1633” for his support of heliocentrism. They continue, “although the Church soon realized that Galileo was right, he was formally vindicated only with a statement by Pope John Paul II in 1992”, and they write that his case has had “a profound influence on both theological and scientific thinking”.
    5. Bennett, Jeffrey; Donahue, Megan; Schneider, Nicholas; Voit, Mark. 2008. The Cosmic Perspective, 5th ed. Addison Wesley.
      Kepler: Discussion is essentially identical to that in the 2002 edition of this book (above).
      Galileo: In contrast to the 2002 edition, there is much on Galileo and the Church in this edition of The Cosmic Perspective. The “Human Adventure…” section remains unchanged (p. 21-22), but there are now two additional paragraphs on Galileo and the Church (p. 78) in the main discussion of Galileo, plus a whole new “Special Topic” section (p. 82). The new material emphasizes that the story was “complex” (the word is used twice). It emphasizes the diversity of opinion among Church officials, emphasizes that the Church supported science in Galileo’s time and now, and even emphasizes that Galileo “counted Cardinals (and even the Pope who later excommunicated him) among his friends [p. 82]”. But these efforts to illustrate the complexity of the situation also introduce opportunities for error—Galileo was never excommunicated, for example.
    6. Bless, R. C. 1996. Discovering the Cosmos. University Science Books.
      Kepler: No mention of Kepler’s faith. The author spends more time than usual trying to explain Kepler’s motivation for developing his laws of orbital motion in terms of a search for a physical rationale for an orbit. The author writes that Kepler’s laws exemplify an important feature of modern science, namely, “the faith that the universe is orderly and knowable, so that one can build theories [p. 123]”.
      Galileo: The book includes a page-long section on “Galileo’s Difficulties with the Church [p. 134]”, in which the author notes that Galileo, “delighted in making [his opponents] appear ridiculous”, and continues, “I mention this to suggest that his difficulties with the Catholic Church need not have occurred”. He goes on to explain that the Church’s position was that, since there was no real proof of this idea that the Earth circles the sun, that idea could not be taught as fact. “Neither side behaved very well in this business,” the author writes, “Galileo may look like a ‘martyr to science’ to us now, but in Galileo’s time… the situation was not so clear”.
    7. Chaisson, Eric; McMillan, Steve. 1995. Astronomy: A Beginner’s Guide to the Universe. Prentice-Hall.
      Kepler: Kepler is described as “a religious man [p. 38]”. The authors do not attempt to describe how he arrived at his ideas: “suffice it to say that he eventually triumphed [p. 38]”.
      Galileo: Two paragraphs on Galileo and the Church (p. 36). The authors state that “in 1616, his [Galileo’s] ideas were judged heretical”.
    8. Chaisson, Eric; McMillan, Steve. 2004. Astronomy: A Beginner’s Guide to the Universe, 4th ed. Prentice-Hall/Pearson Education, Inc.
      Kepler: No mention of Kepler’s religion. No attempt to describe how he arrived at his ideas—the book just mentions that despite “false starts and blind alleys [p. 31]” he arrived at his laws of motion.
      Galileo: Essentially identical to Chaisson and McMillan’s 1995 book.
    9. Fraknoi, Andrew; Morrison, David; Wolff, Sidney C. 2018. Astronomy. OpenStax/Rice University.
      Note: See note on Abell, Morrison, and Wolff (1991).
      Kepler: The book notes that Kepler “studied for a theological career [p. 71]” and that by working with Brahe’s data for Mars, “he eventually discovered that the orbit of that planet had the shape of a somewhat flattened circle, or ellipse”.
      Galileo: Two paragraphs on Galileo and the church. In one (p. 59) the authors state that “Church authorities… had powerful political and economic reasons for insisting that Earth was the center of creation” and that “it was primarily because of Galileo and his ‘dangerous’ opinions that, in 1616, the Church issued a prohibition decree stating that the Copernican doctrine was ‘false and absurd’ and not to be held or defended”. In the second, they state that “the Roman Catholic Church… was looking to assert its authority and chose to make an example of Galileo. He had to appear before the Inquisition to answer charges that his work was heretical, and he was ultimately condemned to house arrest”.
    10. Freedman, Roger A.; Kaufmann, William J. III. 2005. Universe. W. H. Freeman and Company.
      Kepler: No mention of Kepler’s religion. Rather, the authors state that astronomers had assumed celestial bodies moved in circular orbits, because “if a perfect God resided in the heavens along with the stars and planets, then the motions of these bodies would be perfect, too”, and that “Kepler dared to try to explain planetary motions with noncircular curves [p. 70]”.
      Galileo: One paragraph on Galileo and the Church (p. 74-75). The paragraph states that he was “cautioned by the Roman Catholic church” not to promote heliocentrism, but persisted and was sentenced to house arrest for “vehement suspicion of heresy”. The book features a drawing of observations of Jupiter’s moons made by Jesuit astronomers (p. 76—compare to notes here on Kaufmann’s 1985 Universe book).
    11. Freedman, Roger A.; Geller, Robert M.; Kaufmann, William J. III. 2014. Universe. W. H. Freeman and Company.
      Kepler:  Discussion is essentially identical to that in the 2005 edition of this book (see above). The same phrases quoted from the 2005 edition above are found in the 2014 edition (p. 78).
      Galileo: Discussion is largely the same as the 2005 edition, and the same phrases quoted from the 2005 edition are here, too (p. 84-85). There is also some additional material, including a line indicating that the Roman Catholic Church “was a powerful political force in Italy… whose doctrine at the time placed Earth in the center of the universe” and another line noting that the Church “lifted its ban against Galileo’s heliocentric ideas in the 1700s”. Also, the drawing of Jupiter’s moons made by Jesuit astronomers that is in the 2005 edition has been replaced by a different sketch from Galileo.
    12. Hartmann, William K. 1987. Astronomy: The Cosmic Journey. Wadsworth Publishing Company.
      Kepler: Kepler is described as “devoutly religious and a believer in astrology [p. 115]”. Belief in astrology was common at the time, and Tycho Brahe and Galileo Galilei’s beliefs in astrology are not mentioned. The book states that Kepler “was sure that planetary motions must be governed by hidden regularities—‘the harmony of the spheres’” and that he “found something astonishing”, namely that “the orbit that fitted Mars’ motion best was not a circle at all, but an ellipse”.
      Galileo: Three paragraphs on Galileo and the Church (p. 116) include the following: “The Inquisition jurors were inclined to be lenient only if Galileo repudiated his work. The elderly Galileo saw no point in getting himself killed; his book was already published and he had faith that intelligent people could see plain truth through telescopes or in print” and so he recanted.
    13. Impey, Chris; Hartmann, William K. 2000. The Universe Revealed. Brooks/Cole (Thompson Learning).
      Kepler: Much as in Hartmann’s 1987 book, Kepler is described as “deeply religious and a believer in astrology”. And as in that book, Tycho Brahe and Galileo Galilei’s beliefs in astrology are not mentioned (belief in astrology was common at the time). The book states that “the orbit that best fit the observed positions of Mars was not a circle at all, but an ellipse”, and that “Kepler wanted to discover the cause of the regularity in the orbits of the planets [p. 33]”.
      Galileo: One and a half pages on Galileo and the Church (pp. 53-54). Includes discussion of events of 1613-1633 as well as work under Pope St. John Paul II from 1979-1992. The authors note that “the Catholic Church could not stop the spread of new scientific ideas” and invoke “Germany in the 1930’s” as part of this discussion.
    14. Kaufmann, William J. III. 1985. Universe. W. H. Freeman and Company.
      Kepler: No mention of Kepler’s religion. Rather, the author states that circular orbits had been assumed because “since God is perfect, he would use only circles to control the motions of the planets”, and that “Kepler doubted such arguments [p. 58]”.
      Galileo: One paragraph on Galileo and the Church (p. 60), following three paragraphs discussing Galileo’s telescopic observations. The paragraph states that “the Roman Catholic church attacked his ideas because they were not reconcilable with certain passages in the Bible or with the writings of Aristotle and Plato”. The book also features a reproduction of one of Galileo’s drawings, labelled “Galileo’s observations of Jupiter’s moons [p. 61]”. However, the drawing is a copy Galileo made of observations recorded by Jesuit astronomers. Galileo noted it as such, and this note, in Latin, is clearly visible in the book’s reproduction. Galileo’s telescopic discoveries were not attacked by the Church but were rather confirmed by Jesuit astronomers.
    15. Kuhn, Karl F. 1994. In Quest of the Universe, 2nd ed. West Publishing.
      Kepler: The author mentions that Kepler “concentrated on the study of theology”; he makes no further direct mention of Kepler’s religion. The book reports that he “tried various ovals”, and after nine years “found a shape that fit satisfactorily with the observed path of Mars”—the ellipse (pp. 52-53). A “historical note” page (p. 56) on Kepler says that he developed his three laws of motion “almost accidentally, as he searched for other, deeper patterns in the heavens”. It also states that that Kepler was “forced to cast horoscopes—which he personally ridiculed—to support himself and his family”.
      Galileo: Only one paragraph on Galileo and the Church (pp. 68-69), as part of a “historical note” on the “uproar” that Galileo’s support of the Copernican system created. Only the events of 1616 are mentioned as an example of opposition to heliocentrism; no mention is made of the Dialogue and Galileo’s trial (pp. 40, 42-44).
    16. Pasachoff, Jay M. 2002. Astronomy: from the Earth to the Universe, 6th ed. Brooks/Cole (Thompson Learning).
      Kepler: No mention of Kepler’s religion. The book states that “Kepler wanted to discover the cause of the regularity in the orbits of the planets [p. 33]”.
      Galileo: Seven paragraphs on Galileo and the Church (pp. 40, 42-44) include discussion of events of 1613-1633 as well as work under Pope St. John Paul II from 1979-1992.
    17. Pasachoff, Jay M.; Filippenko, Alex. 2002. The Cosmos: Astronomy in the New Mellennium, 3rd ed. Brooks/Cole (Thompson).
      Kepler: No mention of Kepler’s religion. The authors state only that he “succeeded in explaining… the orbit of Mars [p. 98]”.
      Galileo: Six paragraphs on Galileo and the Church (p. 102) that include a brief overview of what happened, mention of Pope St. John Paul II’s comments in 1992, and a statement that today “peace reigns between the Church and scientists, and the Vatican supports a modern observatory and several respected contemporary astronomers”.
    18. Robbins, Robert R.; Jefferys, William H.; Shawl, Stephen J. 1995. Discovering Astronomy, 3rd ed. John Wiley & Sons, Inc.
      Kepler: No mention of Kepler’s religion. The book states that Kepler often “had to earn his living by casting horoscopes, and in fact he cast his own horoscope every day [p. 80]”; and that “something in Kepler’s character kept him working persistently at the problem” of orbits.
      Galileo: This book has a relatively short discussion of Galileo, with only one sentence mentioning him and the Church (p. 82).
    19. Seeds, Michael A. 1998. Horizons: Exploring the Universe, 5th ed. Wadsworth (Thompson) Publishing.
      Kepler: No mention of religion. Kepler is described as knowing little about mathematics at one point (p. 52). There is no discussion of how he arrived at his three laws.
      Galileo: Two pages on Galileo and the Church. Some discussion about how he was “not condemned for heresy” but for “disobeying the orders given him in 1616”.
    20. Theimer, Otto H. 1973. A Gentleman’s Guide to Modern Physics. Wadsworth Publishing Company, Inc.
      Note: This is a physics text, rather than an astronomy text, but it contains a standard discussion of the development of astronomy, which the author calls “the oldest and, perhaps, most typical of the natural sciences [p. 9]”. The purpose of this discussion is “to generate an intuitive understanding of the scientific method and to introduce facts and concepts” that the author will use throughout the book.
      Kepler: The author describes Kepler as “a mystic of the Pythagorean type who believed that numbers and simple geometrical shapes govern the structure of the world. Because he was a Christian Kepler believed that the world was the creation of God; because he was a mathematician, he felt that only mathematics was noble enough to serve as a guiding principle for God’s creation”. The author describes Kepler as “a relentless perfectionist” in trying to find a theory of orbital motion that would agree with Tycho Brahe’s data, who was driven “by a kind of religious belief that a simple formula should exist that would produce perfect agreement” of theory with observations.
      Galileo: The Galileo section is short, and all that the author writes regarding Galileo and the Church is that Galileo “is well known for his hassle with the Church over the validity of the heliocentric theory (which contradicted some passages in the Bible)”.
    21. Zelik, Michael. 1994. Astronomy: The Evolving Universe, 7th ed. John Wiley & Sons, Inc.
      Kepler: No mention of religion. The book focuses on Kepler trying to “fit Tycho’s data” (p. 51).
      Galileo: The book has roughly half of a page on Galileo and the Church (p. 62), focusing on Galileo’s relationship with Pope Urban VIII, who is described as a “friend of Galileo and a patron of the sciences”. The author states that Galileo’s “argumentative spirit promoted his downfall”. A sentence mentions that in 1992 “the Church decided to clear Galileo”.