The ancient Mayan civilization, which existed from approximately 2000 BCE to 1500 CE in present day Mexico and Central America, had a highly advanced understanding of astronomy. They used their astronomical knowledge for many things, including religious rituals, calendar systems, and timekeeping. Their primary focus was on tracking the movements of the sun, moon, and planets, especially the cycles of Venus. Their astronomers managed to calculate the cycle of Venus to within 2 hours of its actual orbit.
The Mayans built many structures to support their astronomical observations, including pyramids, temples, and observatories. The most famous of these structures is the Temple of the Sun in Palenque, Mexico, which is aligned with several solar events. These various events created different sunlight effects within the temple, which the Mayans used to determine when to plant and harvest crops, among other things. They also created accurate calendars that were based on astronomical observations and were used to track the passage of time, as well as to mark significant events such as eclipses, solstices, and equinoxes. The Mayan astronomical knowledge was so advanced that they had accurate eclipse predictions before almost any other world cultures, and their body of observations rivaled the Ancient Greeks.
The short tide video we saw in class made me curious about tides. I looked into the relationship between the tides and the Moon, similar to what we had to do at the end of Homework 4. I wanted to share some of my findings.
Both the Moon and Sun contribute to tides on Earth. However, the Moon has a greater impact on tidal motion. This implies that tides cannot be a result of gravitational force as the Sun’s influence is significantly larger than that of the Moon. Like we found out in Homework 4, the gravitational force of the Moon changes with location on the Earth. This is because the Moon is relatively close to the Earth so distances between the near and far side of the Earth make up a small, but noticeable portion of the overall distance. This difference in gravitational force coupled with the orbit of the Moon are actually what cause tides. Water is constantly influenced by the Moon with the result being the bulging on the closest and farthest side from the Moon. High tides occur at these bulges. One rotation is the equivalent to one day, so usually there is the occurrence of two high tides and two low tides per day.
As I mentioned at the beginning, the Sun also contributes to tides. The difference between the gravitational pull of the Sun at different locations on the Earth is negligible. This means that tides resulting from the Sun remain fairly consistent. As seen in the figure, the Moon’s pull is more variable causing greater differences in tide. This provides insight into the question: what would happen to tides if there was no moon? The Sun would be contributing to tides, so they would still exist. The tides would just be much smaller and the difference between high and low tide would be much smaller as well.
Now that I have discussed the difference between lunar and solar tides, I want to explain the result of having both. This is a simple vector addition problem. When the Sun and Moon are in line with each other, the vectors of their forces are going to be added together meaning the high tides will be higher and low tides will be lower. This is called spring tide. When are the Sun and the Moon aligned? Full and New Moon. This means the moon phases can be used to determine the strength of the tides. Applying this logic, lower high tides and higher low tides will occur when the Moon and Sun’s force vectors are at a right angle with each other. The Sun and Moon are at this right angle during First Quarter and Third Quarter Moon. This is called neap tide. Refer to the above figure from NASA Science to visualize how these vectors influence the resulting tide. Their website also has some other figures which help with understanding tides. The result of both the Moon and the Sun’s gravitational forces is a change in tidal movement both throughout the day and throughout the moon’s phases.
In the late 16th century, a young man by the name of Giordano Bruno set out on a journey of discovery, one that would take him to the very frontiers of scientific knowledge and beyond. Bruno was a man of incredible intelligence and curiosity, driven by a deep passion for the mysteries of the universe. He was a man who was not afraid to challenge the prevailing wisdom of his time and to explore new ideas, no matter the consequences.
Bruno’s quest for knowledge led him to the field of astronomy, where he began to delve into the mysteries of the cosmos. He was fascinated by the stars and the infinite expanse of space that surrounded him, and he longed to understand the nature of the universe and its place in the grand scheme of things.
Bruno’s ideas were bold and revolutionary. He believed that the universe was infinite, with no center and no edge, and that there were countless other suns and planets, each with its own unique set of inhabitants. He also believed that the stars were not simply distant lights in the sky, but were in fact suns, much like our own, with their own set of planets and life forms. This idea is also known as Cosmic Pluralism
Bruno’s views were in stark contrast to the prevailing wisdom of his time, which held that the universe was limited and finite, with the Earth at its center. His ideas were deemed heretical by the Catholic Church, and he was soon accused of heresy and brought before the Inquisition.
Despite the danger, Bruno refused to recant his beliefs. He stood steadfast in the face of persecution, declaring that his ideas were the result of his own observations and the fruits of his own intellect. He refused to compromise his beliefs, even as he was subjected to the harshest forms of torture and imprisonment.
In the end, Bruno was brought to trial, where he was convicted of heresy and sentenced to be burned at the stake. On February 17, 1600, Bruno was led to the Place de Grève in Paris, where he was tied to a stake and burned alive, his body consumed by the flames as he remained steadfast in his beliefs to the very end.
Bruno’s death was a tragedy, a cruel and unjust end to a life of extraordinary promise. But despite his cruel fate, Bruno’s legacy lives on, a testament to the power of the human spirit and the unquenchable thirst for knowledge that drives us all. He was a man ahead of his time, a visionary who dared to look beyond the confines of his world and to imagine a universe that was far grander and more magnificent than anything anyone had ever imagined. And his sacrifice serves as a reminder of the power of the human spirit, and the unending quest for knowledge that drives us all.
To me, one of the most interesting historical phenomena related to the cosmos occurred in modern day Mexico in the year 1531. This is just after the Spaniards had conquered much of the region through bloodshed and war. However, one moment of peace emerged from the area. Our Lady of Guadalupe is a well-known image venerated by millions around the world. There is a whole legend around it, which you can read about at Learn Religions, but it will suffice to say that her appearance and the subsequent chapel led to the conversion of millions of indigenous peoples to Catholicism around the Americas. Furthermore, its presence has seen many miracles, including its miraculous longevity and durability, as well as the supernatural nature of its painting and its eyes.
But the primary purpose of this blog post is to describe the astronomical significance of the tilma (the name of the cloak on which it is painted). Firstly, a general description of the celestial bodies within the image. She stands in front of the sun, with rays emerging from behind her. Also, she stands on the crescent moon. Both of these align with the Bible verse saying, “A great sign appeared in the sky, a woman clothed with the sun, with the moon under her feet, and on her head a crown of twelve star. (Rev 12:1)”. She is also clothed with the tilma covered in stars. These stars were investigated by an astronomer named Juan Hernandez Ilescas.
His investigations found that there are 46 stars on the tilma, and the positioning of their constellations align perfectly with the night sky on December 12, 1531. There are fifteen visible constellations of the possible eighty-nine, as those were the ones seen in the sky on the night of her apparition.
The only difference is that the constellations are reversed on the tilma, making it seem as if the sky was being viewed from above the stars, or as if from outside the universe. Some of the constellations are invisible, as the tilma is not present at those places or there are folds covering them. The constellations hold significance; for example, Leo is positioned over her womb, and the Lion is a common symbol for God in Christianity. Also, the primary star in Leo is Regulus (“Little King”). Corona Borealis means Northern Crown, and is positioned over her forehead, also matching with the verse of Revelations. Finally, the Virgo constellation, meaning Virgin, is positioned over her heart. This refers to her pure heart and perpetual virginity as outlined in the Christian faith.
Her appearance also coincided with the winter solstice (12th of December) of the Julian calendar (22nd of current calendar). This had important cultural significance, indicating the arrival of the longer days and its association with “The Light of the World,” as in her Son in her womb. Furthermore, the winter solstice was a time of fear for the Aztecs, as they believed the celestial bodies to be deities in war, and the winter solstice meant the moon was winning. But the positioning of the Virgin Mary both above and in front of the sun and the moon signaled she was greater than both of their deities.
The final celestial phenomena not seen in the tilma yet present on the day of her apparition is Haley’s Comet, right on the horizon. It is yet another celestial event abounding on the night of her appearance.
I find all of the miracles surrounding the tilma of Our Lady of Guadalupe fascinating. Whether you believe in God or not, the testimonies around the supernatural cloak are still amazing. Also, the astronomical events depicted on the tilma aligning with the night of its creation are astounding to me. The entire situation I find captivating, and I wanted to share it with whomever reads this.
Most people have seen pictures or heard of Stonehenge, an ancient monument on the Salisbury Plain in England. Personally, while I had seen references to Stonehenge in the media, I never actually knew what it was for, or what people thought it was for. It has been difficult for historians to find a definitive answer, as the building of Stonehenge is estimated to have begun over 5,000 years ago, and spanned over the course of about 1,500 years. Historians are fairly certain that Stonehenge was used as a burial site at some point, and many believe Stonehenge was crucial to the ceremonies and/or religion of the people who built it. However, in the 1960’s, astronomer Gerald Hawkins suggested a different possible purpose of Stonehenge: astronomy.
It was always somewhat accepted that if you stand at the center of Stonehenge on June 21st (the day of the summer solstice), you will see a cluster of stones lined up perfectly with where the solstice Sun rises. Hawkins not only confirmed this alignment, but suggested a number of other alignments, and asserted that the arrangement of Stonehenge may have been used to predict eclipses as well. While this theory has excited many people, and may be true, some argue that the people building Stonehenge would not have had the knowledge or data necessary to make so many astronomical predictions. What do you think? Was Hawkins reaching? Do you think the builders of Stonehenge were conscious of the astronomy at play in their arrangements, or do you think the alignments are due to coincidence?
Astronomer Galileo Galilei using a telescope. Galileo is the scientist known for first turning a telescope towards the sky.
Galileo Galilei is one of the most renowned figures in astronomy history, as he was one of the biggest and most meticulous supporters of the heliocentric model of the universe. However, Galileo not only had to fight against the fact that for all of history the idea of the geocentric solar system had been accepted as fact, he also had to deal with the fact that as a devout Catholic, he had to follow under the guidelines of the Catholic Church’s teaching. In Italy during Galileo’s lifetime, The Roman Catholic Church reigned supreme and to claim or try and prove that the earth was not the center of the solar system (and the universe) was deemed as heretical (which is why Copernicus waited until he was on his death bed before publishing his theories on heliocentrism. Despite Galileo’s extremely accurate data and falsification of Aristotelian physics, he was warned several times by the Catholic Church and its leaders to back away from the heretical theory.
Galileo went through a long and arduous period of fending off the church and trying to prove his theories correct through essays and publications. It all came to a head in June of 1633 when he was called before the Roman Inquisition to confess his crime of going against the doctrine of the Catholic Church as well as his sin of heresy. At such an old age (around 70), Galileo was tired of fighting and had done all he could do to prove heliocentrism and had done the work for future scientists to prove him correct. He confessed to the Inquisition and claimed that they were correct (a theory he did not believe). Because he confessed, he was excused from death and instead lived out the rest of his days under house arrest.
Although today we are taught that heliocentrism is correct and it seems like common knowledge, it was certainly not always the case. So many ancient astronomers laid the groundwork for the knowledge we hold today, and Galileo was one the most influential of these.
This is an image of a lifeboat that was sent out to search for walkers who may have been unaware of the changing tides.
High and low tides can pose great challenges and dangers to nature lovers, especially those who enjoy being close to the water. I was originally searching how spring/neap and high/low tides might affect erosion rates; while scouring the Internet, I found this article from the UK (Lancaster Guardian) that details how these tide patterns actually affect human rescue searches. As we discussed in class, a Lancaster official did note that spring tides come with greater magnitudes of high and low tides; in this case, the officials were conducting a search for possible cases of seashore walkers getting cut off from land due to the rapid influx of the spring high tide. In this case, the Lancaster official reminded locals about the pattern of spring tide and even made a joke:
“Tides have a reputation for being unpredictable, but really they follow a timetable more reliable than most trains!”
On a more serious note, it’s important to consider that the amplitude of tides is not solely determined by the moon’s pulls either; while the volume of water may be affected directly by the differentials between far side and near side pull on Earth, the height that tides reach can also be determined by the “container” that the water belongs in. In this Nat Geo article, there is an important consideration for longer, straight beachlines having less violent tides while a more limited space like an inlet could host a tidal range of many meters.
Giant Impact Hypothesis Visual by NASA/JPL-Caltech/T. Pyle from Astronomy
Have you ever considered how Earth got its moon in the first place? Astronomers have come up with several theories for why each planet in our solar system has a certain number of moons, and how these moons formed.
For Earth’s moon, it is thought a collision with another planet shortly after formation of the solar system caused material from the planet to be launched into space. Some of this material was caught in Earth’s orbit and eventually consolidated into the Moon, and this is called the Giant Impact Hypothesis. Another theory is similar, and it purports that the Earth once had two moons due to this collision, but later the moons collided and formed the Moon today. This theory is supported by the fact that the Moon’s surface differs so greatly in shape and material across it. More evidence for this theory is here. Overall, the early solar system was chaotic with plenty of collisions that could have created other planets’ moons as well.
Additionally, plenty of moons are thought to have formed from rings of gas and dust, like Saturn’s rings for example, which eventually consolidated into larger bodies that became moons. For example, Jupiter’s Galilean moons (Io, Europa, Callisto, and Ganymede) likely formed in this way. Although, Jupiter is so large that it likely captured stray asteroids which got caught in its orbit and became moons. Other planets likely could have stolen moons from the orbits of other planets during the early solar system. Orbits are elliptical, and ones with high eccentricity could easily overlap into other orbits.
An important thing to note is that Mercury and Venus do not have moons. Mercury is thought to have had an outer layer of dust and gas, but a collision caused it to be launched out of its orbit, and the planet’s relatively small mass could not provide the gravitational force to keep the material in orbit. On the other hand, Venus is similar in size to Earth and far enough from the Sun to keep potential moons from instead heading to the Sun. It is thought Venus was impacted twice. The first impact created a moon, but an impact later caused the moon’s orbit to become distorted and lead straight into Venus. As the impact imparted such a large force and transfer of angular momentum, Venus’s spin became significantly slower and caused it to spin in the opposite direction.
Ultimately, more research will be required to determine exactly how each moon in the solar system formed, but these theories provide a general idea. More information can be found here.
Astronomy hasn’t always been practiced the way that it is today! For many centuries, different civilizations have conceptualized the universe in a wide range of ways covering the entire spectrums of science and mythology– from this, at the intersection of astronomy and anthropology, the field of archaeoastronomy was born!
The field began with the discovery of Stonehenge in the 1960s, but it has roots dating back to the Great Pyramid of Giza in Egypt (which can claim accurate cardinal orientation!). A majority of the work done in the field concerns alignment, or pointing out the connections between the structures and beliefs of ancient peoples to what we now know to be true about the universe.
Archaeoastronomy became particularly important in 2012 with the infamous ‘End of the World’ panic due to the Mayan Calendar. The Mayan Calendar was at the end of Baktun 13, one of many cycles that they used to categorize time. As scientists have deciphered Mayan texts to learn how they understood time and the universe, they realized that the string of zeroes that would have been displayed on December 21, 2012 did not mean the solar system would be transcendentally aligned with the center of the Milky Way– it simply meant the changeover of an era, similar to the way an odometer flips to zero as it runs.
Have you ever thought about why planets in our night sky sometimes appear to be moving backwards? Well, this phenomenon is known as retrograde motion. It is not as strange as it sounds. Retrograde occurs when a planet is moving in the sky and appears to be moving backwards from our perspective on Earth – but this is really an illusion. This optical illusion is due to the positions and movements of our spaceship Earth. Although it is most noticeable with outer planets in our solar system such as Mars, Saturn and Jupiter, this motion can occur with any planet in our night sky. During retrograde, the planet will appear to slow down, then stop, and then start moving backwards in the opposite direction. But this isn’t ACTUALLY a physical backwards movement of the planet, it is just a result of changing perspectives of out Earth and the planet moving as they orbit the sun at the same time together – its pretty cool!
On retrograde I think everyone is familiar with is Mercury Retrograde. But instead of thinking about this in terms of astrology and changing behaviors, here is a video that explains this famous retrograde in terms of astronomy and science.
