Tag Archives: Calendar

From the Tablet: Why is Ash Wednesday So Late This Year?

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This entry is part 61 of 181 in the series Across the Universe

This column ran in The Tablet for the new year’s issue of 2008, when Easter occurred remarkably early, on March 23. It was relatively early in 2016, on March 27th, when we ran it here. This year, it’s about as late as it can be! Early or late, the explanation is the same… and so probably worth running again. Why is Ash Wednesday so late this year? Contrary to popular conception, the Vatican Observatory doesn’t set the date of Easter. (We don’t cast horoscopes for the Pope, or evangelize UFOs, either.) But since Pope Gregory’s reform of the calendar in 1582 marked the beginning of the Vatican’s support for astronomy, we have a historical connection. Our calendars have always been marked by a confusion of days, planets, and gods. Even today, our week begins with the Sun’s day, followed by the Moon’s day and ending with Saturn’s Day. The month (think, “moonth”) was originally based on the 29.5 day period of the Moon, … Continue reading →

A note on the date of Easter

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This entry is part 28 of 38 in the series Diary

Horst Rademacher,  a seismologist at U C Berkeley, wrote to friends of mine there last weekend, asking about the date of Easter: May I bother you with a question, which is probably trivial for astronomers like you to answer. However neither Peggy nor I could find an answer anywhere. Here is the question: Tomorrow (Apr 1) is Easter. According to the classic definition Easter always falls on the first Sunday after the first full moon after the vernal equinox. That makes sense, because today is full moon, which is the first full moon after the beginning of spring. And tomorrow is Sunday, hence Easter. However, today’s full moon occurred at 5:37 am PDT. Let’s assume, the full moon would have occurred at 5:37 pm PDT. Applying the definition above from a purely California perspective, tomorrow would still be Easter. However, if we were in the Netherlands, in Germany or in the Vatican for that matter, this assumed full moon would … Continue reading →

Across the Universe: Redating Easter?

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This entry is part 155 of 181 in the series Across the Universe

This column first ran in The Tablet in January 2016 The archbishop of Canterbury Justin Welby has recently [2016] announced discussions to redefine the date of Easter. Pope Francis and various leaders of Eastern churches have also expressed interest in a common date that all churches would celebrate together. Easter was originally the Sunday following Passover, the first full moon of the Hebrew year. But the start of the Hebrew year varied from year to year. Jewish months, 29 days long, mirror the phases of the moon, and so every three or four years an extra month is needed to keep that lunar calendar in phase with the seasons. After the destruction of the Temple in AD 70, there was no central Jewish authority to determine when to add that month. Instead, Jews of the Diaspora relied on a Greek formula (devised in 432 BC by Meton) to add seven intercalary months over a repeating 19 year cycle. It was … Continue reading →

#GivingTuesday – November 28, 2017

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Celebrate Worldwide Generosity with Us! Help us support one of our favorite outreach programs; every year the Vatican Observatory Foundation gives hundreds of astrophoto calendars to prison inmates. As one Inmate said: “…I am able to see sights I haven’t seen in 17 years….I am able to look in wonder on such vast creation and just ponder all that is.”  The cost of our annual program $6,000. Your Gift on November 28th will support this and our other outreach programs! Help Us Share God’s Universe through Astronomy! … Continue reading →

Calendars!

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This entry is part 29 of 38 in the series Diary

Happy September the first… and happy Calendar Day! Yes, the official Vatican Observatory Foundation calendar is now available for sale: These calendars have been a tradition for more than ten years. Every month has an excellent astrophotograph, donated to us for our use, by some of the best amateur astrophotographers in the world. The 2018 calendar features work by Damian Peach from the UK (who did the cover photo above), Bernard Hubl from Austria, J-P Metsavainio from Finland, Adam Block from the University of Arizona… and more. Twelve… no, make that, fourteen fantastic images. (Counting the cover, and January 2019.) The calendar itself contains a delightfully eclectic selection of astronomically significant dates. And probably one or two typos, even though Dr. Brendan Thomson (who puts this together for us every year) and I must have proofread it at least three times each. Tell us of a typo and I will send you a cookie. Update: the 2018 calendars are no … Continue reading →

Across the Universe: Fast changes

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This entry is part 125 of 181 in the series Across the Universe

This column first ran in The Tablet in June 2013 Summer began [in 2013] on Friday morning, 21 June, at 5:14 am GMT…in the northern hemisphere, of course; south of the equator, it’s winter. [The summer solstice 2017 in Northern Hemisphere occurred at 4:24 am GMT on Wednesday, June 21.] This definition is based on the precise orientation of the Earth in its orbit. The Earth is tilted relative to its orbit, and like a gyroscope its spin axis stays pointed in the same direction, year round. In a convenient coincidence for navigators, our north pole is pointed near the star Polaris. Polaris is not directly above the Sun; it’s directly above Earth’s tilted spin axis. In June, the Earth is in the part of its orbit where it’s on one side of the Sun, and Polaris is on the other side. The northern half of the Earth, tilted towards Polaris, is also tilted towards the Sun; that’s why it gets warmer. The … Continue reading →

2016 Calendars are available!

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This entry is part of 38 in the series Diary

  Every year, the Vatican Observatory Foundation publishes a calendar featuring fantastic astronomical images from amateurs around the world… and noting dates of particular interest to astronomers. They can be purchased online here… This year’s calendar is out, and it looks great. (OK, so as proofreader I missed a couple of glitches, which immediately made themselves obvious as soon as I opened up the printed version. Nothing as bad as a couple years ago when we got Galileo’s birthday wrong!) On the back, I always write a pithy little paragraph or two that nobody reads. As a freebie for readers of The Catholic Astronomer, here’s what I put there this year: A few years ago, a couple of cosmologists who styled themselves as atheists attempted to show that there was “no need for God” to start the universe, at the moment popularly known as the Big Bang. They proposed thatthat a quantum fluctuation in the zero-energy vacuum field of the … Continue reading →