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Astronomy Q&A Live Stream

Astronomy Q&A Live Stream

On April 9 I hosted my first Astronomy Q&A live stream on Facebook. I responded to questions about the planets and then to questions made to me by viewers of the live stream.

It was fun but wore me out. If I do another live stream in the future, I may reduce the time or have a moderator/interviewer to make the stream more dynamic. If you have any other suggestions, feel free to let me know.

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Astronomy Q&A Live Stream Announcement

Astronomy Q&A Live Stream Announcement

After getting your feedback, I’ve scheduled my first Astronomy Q&A live stream for Monday, April 9, at 6:45 pm Pacific Time via Facebook Live.

I’ll start out by answering questions about the planets that middle- and high-schoolers of Summit Academy in Cottonwood asked me recently when I spoke to them about the Origin of the Universe. Then I’ll take on any questions that viewers of the live stream submit. I expect about ten to fifteen viewers, so there is a good chance I will be able to respond to all questions. Hope you can join!

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Why Does Spring Start March 20?

Why Does Spring Start March 20?

The first day of spring and the first day of fall happen on equinoxes, when the plane of Earth’s equator passes through the Sun’s center. Day and night are appoximately (but not exactly) of equal length.

Before Julius Caesar introduced his calendar in 45 BC in order to approximate the tropical (solar) year, the seasons had never been fixed to calendar dates. (In this blog post, I won’t go into all the details about the different ways of measuring years, which I have done elsewhere.) In the Roman system, calendar years were at first only 304 days (the Calendar of Romulus), which were split into ten months, March being the first. This is why the our months September through December are misaligned with the numbers 7 (septem), 8 (octo), 9 (novem), and 10 (decem). Through the reform of King Numa Pompilius around 700 BC, January and February were added. At this time, however, some months had fewer days than they do now, and the year consisted of only 354/355 days. To make the calendar follow the seasons a little more closely, the Pontifex Maximus (the head of the main college of priests in ancient Rome) was given the authority to insert an extra month between February and March. Since the Pontifex Maximus ended up wielding this tool for political purposes, it was not long before the seasons and year were misaligned. To re-align the year, Julius Caesar made 46 BC last 445 days, and then implemented his new calendar on January 1, 45 BC.

In 45 BC, March 25 was the first day of spring. The Julian year (365.25 days), however, is slightly longer  than the tropical year (365.24217 days). This caused the seasons to drift forward in the calendar. After a few centuries, spring was beginning on March 21, when a decree from the Council of Nicaea (AD 325) included the vernal equinox as part of the equation for determining the date of Easter (the Sunday after the first Full Moon after the vernal equinox) so that Christians throughout the world would celebrate Easter on the same day. No change was made to the calendar at this time, however, and the seasons continued to drift. By the time of the Gregorian calendar reform in 1582, the vernal equinox fell on March 11. Pope Gregory XIII wanted to bring it back to where it was when at the time of the Council of Nicaea. So in 1582, to bring the seasons back on track, ten days were skipped. Those who heeded the Pope’s decree in 1582 went to bed Thursday, October 4, and woke up Friday, October 15. To keep the seasons on track, the rule for leap years was also changed: years that are multiples of 4 have leap days (just like in the Julian calendar), except years that end in 00, except years whose digits before the 00 are multiples of 4. This meant that the years 1600 and 2000 were leap years (16 and 20 are multiples of 4), whereas the years 1700, 1800, and 1900 were not leap years. As a result, the Gregorian year is 365.2425 days, still not matching totally to the tropical year, but a good deal closer than the Julian calendar. Since the Gregorian calendar reform came from the Catholic Church, non-Catholic countries delayed even centuries in making the switch (e.g., England in 1752, Russia in 1918). This, however, is the calendar the Western world follows today.

The vernal equinox falls on March 20 this year, but some years it will fall on March 19; some years, on March 21. The oscillation is mainly due to leap days being observed in some years and not in others. The first days of other seasons differ by plus or minus a day as well. Here’s a chart that shows the transition times between seasons.

Although the 25th of March, June, September, and December no longer coincides with an equinox or solstice, it still keeps some of the meaning that was associated with its previous status. In Christianity, December 25, of course, is the birth of Christ. Nine months prior, March 25, is the feast of the Annunciation to Mary and Incarnation of the Son of God, as well as the traditional date for the Crucifixion. No wonder J.R.R. Tolkien, a devout Catholic, picked March 25 as the date for the destruction of the One Ring.

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The Church’s Role in Science

The Church’s Role in Science

Last month I spoke at the Vandal Catholic Encounter on the topic of the Church’s role in science. Here is a link to the video recording. I apologize for how much you’ll have to strain to listen and see. In the future I hope to write an article to revisit the topic in more depth and perhaps do a different video recording.

In summary, the Church is not afraid of science. In fact, the Church embraces science and uses it. For example, in the lifetime of Galileo, though before the disagreements over cosmology surfaced, the Gregorian calendar reform took place. This calendar reform used humankind’s improved knowledge about the seasons, thanks to the science of astronomy. When Galileo first used a telescope and discovered Jupiter’s moons not orbiting the Earth, he began to promote heliocentrism openly. He was right about the Earth orbiting the Sun and about interpreting some passages of Scripture metaphorically. The Church and many people at the time held Galileo’s ideas suspect and asked for proof. Galileo was wrong that the tides prove the Earth’s motion; the tides are caused by the Moon and Sun. For promoting heliocentrism so vehemently after he had promised not to, he was sentenced to house arrest, where he lived the last decade of his life. Proof for the Earth’s motion came in the 19th century with Foucault’s pendulum. Pope St. John Paul II, on October 31, 1992, asked for forgiveness for how Galileo was treated (although by no means was he tortured or killed; rather, he was given first-class lodging during his trial in Rome). John Paul also said, “In fact the Bible does not concern itself with the details of the physical world, the understanding of which is the competence of human experience and reasoning.” (Read a translation of his speech here.) Not only does the Church recognize the role science has in advancing human knowledge about the universe we live in, but the Church also has a role in science. Institutions like the Vatican Observatory that participate in relevant science are an excellent example of this.

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Solar Eclipse in Retrospect

Solar Eclipse in Retrospect

 

The two minutes and six seconds of totality I experienced were otherworldly. Time had paused and I was submerged into an ethereal reality. I had spent so much time preparing for this, and yet it passed by so quickly. As the Moon’s shadow had approached from the west, an irrational fear took hold of me and I felt as if I were supposed to resist the imminent darkness but was powerless to do so. Intellectually I knew that was false, and I soon returned to peace once totality began. It was as if a gaping hole in the sky suddenly opened, surrounded by the solar corona. Stars and planets became visible. Was I dreaming? No, this was the awe-inspiring experience of a total solar eclipse.

Here is a two-minute summary video of what I captured:

The first half is simply the eclipsed Sun. The second half is a view of the west to see the approaching shadow along with a sheet spread out in the foreground to display shadow bands in the seconds before and after totality. No video can do justice to a total solar eclipse. It’s the experience of a lifetime.

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Solar Eclipse, Part 4: To Scale and Not To Scale

Solar Eclipse, Part 4: To Scale and Not To Scale

To scale or not to scale, that is the question;

Whether ’tis nobler in the mind to suffer

The slings and arrows of disproportions

Or to take a ruler to that sea of troubles

And, by measuring, correctly depict them.

…                      Aye, there’s the rub.

Shakespeare aside, when you see a diagram depicting an eclipse, a caption oft accompanies it, clarifying that it’s not to scale. Why? Here’s why. Look at this diagram. This one is to scale.

This diagram of the Sun, Earth, and Moon is to scale. The night-time side of the Earth is not darkened in this diagram.

Look how much space there is between the Sun and the Earth! Can you even see the Moon? I programmed it into the plot; it’s just so small. A diagram that is to scale helps us understand the relation between the sizes of the celestial bodies and the relative distances between them. Nevertheless, it does not help us understand what is going on during an eclipse. This is one reason why we have diagrams that are not to scale.

This diagram of the Sun, Earth, and Moon is not to scale. This diagram shows the configuration of these celestial bodies during a solar eclipse.

Here we can see that the Moon is in between the Earth and the Sun, and the Moon’s shadow falls upon the Earth. This doesn’t happen every time the Moon passes between the Earth and Sun because the shadow usually flies over the North Pole or under the South Pole. During two different intervals of about 33 days each year, the Moon’s shadow could fall upon the Earth. Only during these intervals can we get eclipses (both lunar and solar).  Whether an eclipse happens depends on the Moon’s phase. Which type of solar eclipse occurs (total, annular, or partial) depends on the relative distances between the Earth, Moon, and Sun. These are constantly changing because orbits are not perfect circles but ellipses. I hope to go into further detail about this in a future post. This should at least help us understand why to scale diagrams and not to scale diagrams are both helpful, but for different reasons.

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