An important connection historically between religion and science, especially astronomy, was the development of reliable calendars that could be used to schedule religious holidays. This eventually led to the Vatican’s support of astronomy in general, now found for instance in the Vatican Observatory. The history is fascinating in its own right (if sometimes mathematically technical), and it demonstrates the cooperation between religion and science at its best.
Astronomy, Calendars And Religion
- Article (PDF)
- 10 pages
- General audience
This chapter by Fr. Juan Casanovas, S. J., an astronomer with the Vatican Observatory, from the book The Heavens Proclaim: Astronomy and the Vatican, gives an explanation of how our religious and civil calendar has changed over time, from the lunisolar Hebrew calendar to the Gregorian calendar, and comments on proposed future reforms.
Fixing a Date for Easter? A discussion about time
- Article (blog post)
- 1000 words
- General Audience
A post by Fr. James Kurzynski on The Catholic Astronomer website. “To fix the date of Easter would help establish a more predictable rhythm to the liturgical year for parishes [and also] may assist in the reconciliation process between the East and West.”
From the Tablet: Why is Easter So Early This Year?
- Article (blog post)
- 600 words
- General Audience
A post by Br. Guy Consolmagno on The Catholic Astronomer website, reprinting an article from The Tablet about calendars and determining the date of Easter.
What’s significant is the underlying principle behind this arbitrary formula. The Sabbath was made for man, not man for the Sabbath: our religious feasts are not controlled by the Moon. And so future colonists on Mars or beyond can set Easter for whatever date best suits them.
Gregorian Reform of the Calendar
Book (PDF)- 324 pages
- University level
Proceedings of the Vatican Conference to Commemorate the 400th Anniversary of the Gregorian Calendar, published by the Pontifical Academy of Sciences.
Click here for the book from the Pontifical Academy of Sciences web site.
Holy Week and Easter: The Collision Point of Measured Time!
- Article (blog post)
- 1000 words
- General audiences
A post by Fr. James Kurzinski on the Catholic Astronomer website. “In short, the interplay between sacred time and mechanical time helps us appreciate the reason why we measure time in the first place: to reflect on life’s meaning and purpose.”
Misplaced Obsessions: Understanding Why Christmas Is On December 25th.
Article (blog post)- 1500 words
- General audiences
Fr. James Kurzynski writes on the subject of the date of Jesus’s birth in this post on The Catholic Astronomer blog. Know “the date” is complicated, as Fr. Kurzynski explains:
So, can we find December 25th referenced as the date of Jesus’ birth in the writings of the early Church Fathers? Yes, we can… with some presumptions that are VERY important to take into account. A basic Google search on when we find the first reference to December 25th as the date of Jesus’ birth will bring you to Hyppolytus of Rome (170AD – 235AD). Most online citations will boldly affirm that Hyppolytus wrote that Jesus was born on December 25th. The problem is, that’s not what Hyppolytus said. He actually said that Jesus was born on the 25th day of the ninth month. What Hyppolytus is referencing is the Jewish month of Kislev. Of particular interest, the 25th of Kislev in Jewish culture is the celebration of Hanukkah or the “Feast of Lights.” Might there be a connection being made between this Jewish feast and Jesus as the “light of the world?”
To get from the 25th of Kislev to December 25th, we first make a pit stop at the Julian Calendar, which was determined to be slipping each year through the work of the first Vatican Observatory in the Tower of the Winds, leading to the reformed Gregorian Calendar. The Christian West embraced the Gregorian reforms while the Christian East chose to remain on the Julian Calendar. This is why, to this day, there are two dates in the Christian world for the celebration of Jesus’ birth: December 25th in the Christian West and January 7th in the Christian East. Further, we see that the Jewish calendar is a lunar calendar so the 25th of Kislev, Hanukkah, seldom coincides with December 25th. In short, the presumption of when Jesus was born is far more difficult to pin down than one would think.
The Leap Second Debate: Rational Arguments vs. Unspoken Unease
Article (book chapter)- 9 pages
- High school level and above
A brief, somewhat “tongue-in-cheek” essay by Fr. Paul Gabor, S. J., an astronomer with the Vatican Observatory. Gabor provides a brief historical overview on the subject of time, standards, power, and societies. This essay was published in The Science of Time 2016: Time in Astronomy & Society, Past, Present and Future, of which Fr. Gabor is a co-author. Gabor writes:
The ancient and sacred task of timekeeping, linking the eternal with the
everyday, is one of the oldest missions of astronomy, originating long before the
dawn of written history. The succession of timekeeping schemes throughout
millennia has been a search for a balance between the practical and the symbolic.
In the current Leap Second Debate, there are rational arguments, focused on
practical considerations, and there is a certain unspoken unease, emerging from
the symbolic substrata of the issues involved…. [T]his
paper will examine the presuppositions and perceptions overshadowing the debate:
astronomical conformity, continuity, timelessness, (ir)rationality, the Enlightenment,
etc. We shall study the historical evidence represented by the various
calendric traditions and situate the Leap Second Debate in a broader context of
cultural history and history of thought. Our underlying purpose is to facilitate the
debate by shedding some light on its caliginous but potent undercurrents.
Click here for a preview, courtesy of Google Books.
The Mystery That Keeps Neil deGrasse Tyson Up At Night
- Video
- 9 minutes
- General audiences
This January 2018 clip from The Late Show with Stephen Colbert features Colbert and Tyson discussing a number of things, among which is a diversion into Pope Gregory XIII and the Gregorian calendar, Jesuit astronomers, the Vatican Observatory, and Fr. Georges Lemaître (who first developed the Big Bang theory), and “Team RC” (RC being “Roman Catholic”).
Misplaced Obsessions: Understanding Why Christmas Is On December 25th.
- Article (blog post)
- 1500 words
- General audiences
Fr. James Kurzynski writes on the subject of the date of Jesus’s birth in this post on The Catholic Astronomer blog. Know “the date” is complicated, as Fr. Kurzynski explains:
So, can we find December 25th referenced as the date of Jesus’ birth in the writings of the early Church Fathers? Yes, we can… with some presumptions that are VERY important to take into account. A basic Google search on when we find the first reference to December 25th as the date of Jesus’ birth will bring you to Hyppolytus of Rome (170AD – 235AD). Most online citations will boldly affirm that Hyppolytus wrote that Jesus was born on December 25th. The problem is, that’s not what Hyppolytus said. He actually said that Jesus was born on the 25th day of the ninth month. What Hyppolytus is referencing is the Jewish month of Kislev. Of particular interest, the 25th of Kislev in Jewish culture is the celebration of Hanukkah or the “Feast of Lights.” Might there be a connection being made between this Jewish feast and Jesus as the “light of the world?”
To get from the 25th of Kislev to December 25th, we first make a pit stop at the Julian Calendar, which was determined to be slipping each year through the work of the first Vatican Observatory in the Tower of the Winds, leading to the reformed Gregorian Calendar. The Christian West embraced the Gregorian reforms while the Christian East chose to remain on the Julian Calendar. This is why, to this day, there are two dates in the Christian world for the celebration of Jesus’ birth: December 25th in the Christian West and January 7th in the Christian East. Further, we see that the Jewish calendar is a lunar calendar so the 25th of Kislev, Hanukkah, seldom coincides with December 25th. In short, the presumption of when Jesus was born is far more difficult to pin down than one would think.
Fixing a Date for Easter? A discussion about time
- Article (blog post)
- 1000 words
- General Audience
A post by Fr. James Kurzynski on The Catholic Astronomer website. “To fix the date of Easter would help establish a more predictable rhythm to the liturgical year for parishes [and also] may assist in the reconciliation process between the East and West.”
From the Tablet: Why is Easter So Early This Year?
- Article (blog post)
- 600 words
- General Audience
A post by Br. Guy Consolmagno on The Catholic Astronomer website, reprinting an article from The Tablet about calendars and determining the date of Easter.
What’s significant is the underlying principle behind this arbitrary formula. The Sabbath was made for man, not man for the Sabbath: our religious feasts are not controlled by the Moon. And so future colonists on Mars or beyond can set Easter for whatever date best suits them.
The Leap Second Debate: Rational Arguments vs. Unspoken Unease
- Article (book chapter)
- 9 pages
- High school level and above
A brief, somewhat “tongue-in-cheek” essay by Fr. Paul Gabor, S. J., an astronomer with the Vatican Observatory. Gabor provides a brief historical overview on the subject of time, standards, power, and societies. This essay was published in The Science of Time 2016: Time in Astronomy & Society, Past, Present and Future, of which Fr. Gabor is a co-author. Gabor writes:
The ancient and sacred task of timekeeping, linking the eternal with the
everyday, is one of the oldest missions of astronomy, originating long before the
dawn of written history. The succession of timekeeping schemes throughout
millennia has been a search for a balance between the practical and the symbolic.
In the current Leap Second Debate, there are rational arguments, focused on
practical considerations, and there is a certain unspoken unease, emerging from
the symbolic substrata of the issues involved…. [T]his
paper will examine the presuppositions and perceptions overshadowing the debate:
astronomical conformity, continuity, timelessness, (ir)rationality, the Enlightenment,
etc. We shall study the historical evidence represented by the various
calendric traditions and situate the Leap Second Debate in a broader context of
cultural history and history of thought. Our underlying purpose is to facilitate the
debate by shedding some light on its caliginous but potent undercurrents.
Click here for a preview, courtesy of Google Books.
Holy Week and Easter: The Collision Point of Measured Time!
- Article (blog post)
- 1000 words
- General audiences
A post by Fr. James Kurzinski on the Catholic Astronomer website. “In short, the interplay between sacred time and mechanical time helps us appreciate the reason why we measure time in the first place: to reflect on life’s meaning and purpose.”
These Are Not Your Mother’s Sundials: Or, Time and Astronomy’s Authority
A perpetual calendar to keep track of religious festivals and lunar phases.
- Article
- 26 pages
- University level
A discussion by Sara Schechner of the Collection of Historical Scientific Instruments, Department of the History of Science, Harvard University, regarding sundials in the collection of the Adler Planetarium. This essay was published in The Science of Time 2016: Time in Astronomy & Society, Past, Present and Future, of which Fr. Pavel Gabor, S. J., an astronomer with the Vatican Observatory, is a co-author. Schechner writes:
Drawing upon the exquisite collection of sundials and time-finding instruments at the Adler Planetarium in Chicago—currently being catalogued by the author—this essay offers examples of sundials made of silver, gilt brass, ivory, wood, and stone between 1500 and 1900. They were designed to be portable or fixed, pocket-sized, or monumental, but all did more than tell the time. By critically examining them, we can see the influence of the cultures in which they were made and used. These material objects tell stories of race, empire, labor, religion, fashion, and politics. And by so doing, the sundials exhibit the relationship of time in these concerns.
Click here for a preview of this article, courtesy of Google Books.
Astronomy, Calendars And Religion
- Article (PDF)
- 10 pages
- General audience
This chapter by Fr. Juan Casanovas, S. J., an astronomer with the Vatican Observatory, from the book The Heavens Proclaim: Astronomy and the Vatican, gives an explanation of how our religious and civil calendar has changed over time, from the lunisolar Hebrew calendar to the Gregorian calendar, and comments on proposed future reforms.
The Mystery That Keeps Neil deGrasse Tyson Up At Night
- Video
- 9 minutes
- General audiences
This January 2018 clip from The Late Show with Stephen Colbert features Colbert and Tyson discussing a number of things, among which is a diversion into Pope Gregory XIII and the Gregorian calendar, Jesuit astronomers, the Vatican Observatory, and Fr. Georges Lemaître (who first developed the Big Bang theory), and “Team RC” (RC being “Roman Catholic”).
Gregorian Reform of the Calendar
- Book (PDF)
- 324 pages
- University level
Proceedings of the Vatican Conference to Commemorate the 400th Anniversary of the Gregorian Calendar, published by the Pontifical Academy of Sciences.
Click here for the book from the Pontifical Academy of Sciences web site.