Blog 2: Tides

Posted on February 12, 2024 by Charles Knoll

Tides represent the ebb and flow of ocean waters, orchestrated by the gravitational influences of both the moon and, to a lesser degree, the sun. As the moon orbits the Earth, its gravitational force interacts with our planet. Despite the moon’s relatively small mass, its gravitational pull, although not immense, varies across the Earth’s surface since there is a difference in distance. This variance creates what is known as a “stretch force” or tidal force, resulting in two tidal bulges—one facing the moon and another on the opposite side. This stretch is akin to the effect of stretching a rubber band. 

Furthermore, although the sun’s gravitational pull is significantly stronger due to its larger mass, its impact on tides is minimal. The slight difference in gravitational force across the Earth’s diameter fails to produce a noticeable tidal bulge. However, when the gravitational forces of the moon and sun align during specific lunar phases, such as the full and new moons, they combine to generate larger tidal variations, known as “spring tides.” Thus, while the sun may not directly create tidal bulges, its synchronized alignment with the moon amplifies tidal changes.

Source: Photo

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Blog Post 2: How Tides Work

Posted on February 11, 2024 by Nicholas Fleisher

Chapter 4 of the textbook provided a detailed analysis of how tides are the result of the gravitational attraction between the earth and moon. In my blog post, I’d like to demonstrate my knowledge of the subject matter in preparation for the upcoming test in order to solidify my understanding of the matter.

As stated, tides are the result of gravity attracting the moon and earth together. The gravitational attraction of each part of the Earth to the Moon becomes weaker as we go from the side of Earth facing the Moon to the side facing away from the Moon. This difference in attraction creates a sort of “stretching force” or tidal force, that stretches the entire Earth to create two tidal bulges: one facing the Moon and one opposite the moon.

I appreciated the analogy provided that compared this to a rubber band being stretched. The earth is stretched on both sides of the rubber band even though the Moon is tugging harder on only one side.

So, the tides are created by the difference in force of attraction between the Moon and different parts of Earth. There are two daily high tides that occur as Earth rotates through the two tidal bulges. Low tide occurs when the location is at the points halfway between the two tidal bulges. The tidal cycle of the two high tides and two low tides takes about 24 hours and 50 minutes, so each high tide occurs about 12 hours 25 minutes after the previous one.

The sun also exerts tidal force on the Earth, causing Earth to stretch along the Sun-Earth line. However, the gravitational force between Earth and the Sun’s mass is much greater than that between Earth and the Moon, which is why Earth orbits the Sun. Overall tidal force caused by the sun is less than half of that of the moon because of the relative distance between the two pairs.

Because tidal forces stretches Earth itself, the process creates friction, called tidal friction. the effects of this are that the Moon’s gravity always pulls back on the bulges, slowing Earth’s rotation. The gravity of the bulges also pulls the Moon slightly ahead in its orbit, adding orbital energy that causes the Moon to move farther from Earth.

The concept of tides also relates to the conservation of angular momentum principle because the Moon’s growing orbit gains the angular momentum and energy Earth loses as its rotations slows. Source of image

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Blog Post 2 – Gravity

Posted on February 11, 2024 by Thomas Shelton

“Animation vs. Physics “ by Alan Becker on Youtube

Before we get started, the video linked above is phenomenal. If you have any interest in physics, astronomy, astrophysics or anyting related, I cannot recommend this video enough. It encompasses all of these topics in a fun animated way that also gives Interstellar vibes with its intricacies. The screenshot above is what as known as a gravity-assist maneuver, or more slangily, and in my opinion more fun, “The Gravitational Slingshot.” In short, the way it works, is when an object (comet, ship, etc.) is on a path to fly past a planet, but close enough in proximity that said planet’s gravitational pull is strong enough to alter the course of the object. The important piece here is that the object must be moving with a large enough initial velocity such that it has enough momentum so that it does not get sucked and stuck in orbit of the planet. Essentially a sling-shot maneuver is used as a direction change while simultaneously picking up speed. This maneuver has been used several times before by NASA. This goes to show how the force of gravity can be “harnessed,” and what amazing things we can do with it.

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Gravity holds the universe together

Posted on February 11, 2024 by abbieychen

Gravitational force, why planets have orbits, and how we know that black holes exist

When you think of gravity, you might think of the force that makes apples fall on people’s heads (talking about you, Newton!). But it’s also why planets have orbits! Any two objects in space have a gravitational force between them. Kepler’s and Newton’s laws come together to describe characteristics about orbits, and also why things orbit.

Enter….. the Universal Law of Gravitation, discovered by #1 gravity enthusiast Isaac Newton! (Inspired by Kepler, of course). This is how it works: Every mass attracts other masses due to the gravitational force. The strength of the gravitational force between 2 objects is directly proportional to the product of their masses, and decreases with distance between them.

This explains why planets orbit! The gravitational force between two objects holds them together. However, the crazy thing is that Newton discovered unbound orbits. This is when an object escapes the force of gravity and has a parabolic/hyperbolic path, rather than an ellipse.

One common misconception is that smaller mass orbits around the larger mass. But what really happens is that objects orbit around their common center of mass, which is located much closer to the larger mass! This is why the Earth orbits around the Sun, because the Sun is x times more massive than the earth. The center of mass is basically inside of the Sun:

The Sun is so massive! (Image Credit: Kaiser Science)

Binary star systems are another great way to see this phenomenon. When the stars are around the same mass, it looks like they are both moving around the point in between them!

A binary star system and orbits visualized! (Image Credit: Parnika Singh)

The great thing about these equations from Newton and Kepler are that future astronomers can use them and figure out unknown quantities. For example, if you know the orbital period and average distance of some object, you can calculate the mass of the other object, by using Kepler’s 3rd Law (Newton’s version), which included the masses and gravitational force! If one mass is way bigger then we can just pretend the smaller mass isn’t there. That’s how we know the mass of the sun! And that’s also how we know that black holes exist, because we have observed stars orbiting around “nothingness”.

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The Laws of Conservation and How They Connect Us to the Universe

Posted on February 10, 2024 by Landon Peaden

New Scientist

The poetically minded will sometimes refer to humanity as being made of “star stuff” to give some higher, grander description to our existence. No, we aren’t just a bunch of intelligent animals bickering with each other as we try to see who can destroy the world first as we’re flying through the vast emptiness of space. We’re special, made up of the ingredients that shape a cosmos far beyond our comprehension. We’re more than what we actually are.

And in a literal sense, that’s true. The elements and atoms that make up our bodies can all trace their origins to cosmic dust and the Big Bang. Stars create all of the periodic elements that comprise the universe.

But perhaps a better approach would be to point out that we carry on the very life of stars within ourselves, not just fragments and unintended runoff from the burning of their cores. Because due to the laws of conservation, the universe’s energy continues within us. The same energy that fueled a massive star is flowing through our veins. And this energy was intentional, created by the stars to live, just as we depend on it now. The elements that make us up? The stars don’t really need them, other than hydrogen and helium. Just happy accidents that made it possible for us to exist.

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Tides During a Superstorm

Posted on February 10, 2024 by Adriana Santos
Graph showing the tide height during Hurricane Sandy. NOAA

As we know, the moon controls the tides, but what happens when the perfect circumstances come together and a storm is involved? This is part of what happened during Hurricane Sandy. In my Introduction post, I shared with everyone I am from New Jersey and love going to the beach, so back in 2012 when Hurricane Sandy destroyed almost all of the beaches I know and love, I started to wonder what the moon had to do with it.

So here’s the thing, the moon’s gravitational pull controls the tides, causing bulges, and therefore high tides. When there is a full moon, the tides, called spring tides, are at full force because the Sun, Earth, and Moon are in alignment. On October 30, 2012, the moon was full, and the hurricane swept through, with storm surges coming through during 3 high tide times, causing record-breaking tides in some areas. Some of the damage from Hurricane Sandy is still seen today, and after the storm major rebuilding had to begin due to the tides and storm surges. If the moon had not been full would the impact of the tides have been as bad?

Check out this video to see the full effects of Superstorm Sandy.

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Escape Velocity and Space Exploration

Posted on February 9, 2024 by katie shapiro
Escape velocity required to escape Earth’s orbit: Collegedunia Team

In our generation, space exploration has been an extremely valuable way to learn more about our solar system and our galaxy, the Milky Way. It is astounding that humans have been able to set foot on the moon, and that astronomical research centers have sent probes to a variety of astronomical objects within our galaxy, including planets. However, how is it possible that we are able to have objects, such as rockets, leave earth to explore the unknown within space? One main component of this is escape velocity, which was revealed by Issac Newton in the 1700’s. This is the speed that is required for any object to leave or escape a gravitational pull. One common example of this, is Earth’s escape velocity which is approximately 11.2 km/s, which is very fast! In fact, the escape velocity is about 34 times the speed of sound. The escape velocity was founded upon the important principle of the conservation of energy, in which energy cannot be created or destroyed. The equation for escape velocity implies that the final kinetic and potential energy are equal to zero due to an infinite distance. So the initial kinetic and potential energy are set equal to zero and the final equation is ve = SqrRt (2GM/R). Additionally, the escape velocity depends on where the object is in relation to the planet. One example, is that near the equator in the east, the escape velocity is less than the escape velocity in the equator in the west. However, a more commonly known example is that the escape velocity depends on the altitude of where the object is in relation to the planet. For example, if it is further away from the surface, then the escape velocity is much less, than if the object was at the surface because the distance is greater. This is seen in the equation listed above because the square root of R (distance) is inversely related to escape velocity. This understanding is important when applied to rockets escaping earth. When they are launched they will orbit Earth near the surface with an orbital velocity. In this orbit they have to reach a certain velocity in order to escape the gravitational pull that was initially holding the rocket to earth. Once the escape velocity is acquired, the rocket can then escape Earth’s gravitational pull, regardless of its mass, and reach its assigned destination. It’s crazy to think that without Issac Newton’s outstanding work on gravity and his initial finding of escape velocity, we would not have had the outstanding space exploration that we have today!

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Historical Astronomers in Context

Posted on February 8, 2024 by Jonas Kobza

Nicolaus Copernicus – 2/19/1473 – 5/24/1543

Nicolaus Copernicus the first in the modern era (C.E) to develop a model of the universe with the sun at its center, rather than the earth. His work sparked the Copernican Revolution, a paradigm shift which paved the way for the works of Kepler, Galileo, Newton, and others. Copernicus was also the first to propose that the day/night cycle of earth was caused by a rotation on its axis, rather than the earth rotating around the sun. Copernicus’ model paved the way for future astronomers to unlock more about our place in the universe.

Events in Copernicus’ lifetime

Columbus discovers the New World (1492) – This discovery sparked European colonization of the Americas, and the exchange of goods and ideas between Europe and the New World. It also caused extreme violence and disease against the indigenous peoples. 

Protestantism Reformation was started by Martin Luther (1517) – The protestant reformation was a religious movement started in the early 16th century. It had many social and cultural consequences, such as challenging the authority of the Catholic Church and Pope. It also helped to promote increased education and critical thinking through movements such as skepticism.  

Historical Figure Alive 

Niccolò Machiavelli (1469-1527) – Considered the creator of modern political science, Machiavelli’s book “The Prince” is guide for political leaders to better control, lead, and win support over their people.

Reflection

Copernicus lived throughout the Renaissance, a time when middle ages/dark ages ideals of philosophy, science, and art, were challenged. It is no coincidence that Copernicus’ theory of heliocentricity was published after the Protestant Reformation began. This is because Martin Luther, and other reformers such as John Calvin challenged previous ideals such as church and papal infallibility, or the idea that the Pope and Church are without error in their decisions and teachings. This laid the groundwork for Copernicus, and later Galileo and Kepler to challenge the church with their scientific research. Without the movements of the Renaissance and Protestant Reformation, they may never have pursued astronomy and science, and never challenged previous beliefs.

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Historical Astronomers in Context

Posted on February 6, 2024 by Alyssa Ballard

I chose the astronomer Johannes Kepler who was born on December 27th, 1571 in Germany and died on November 15th, 1630 (age 58) in Germany. In the timeframe that Kepler was alive, Shakespeare died, the thirty-year war began, and the protestants began their revolt against the Catholics. Overall this assignment helped me realize more of what people were doing back then, and why so many people were astronomers at that time. There were so many artistic and historic things going on, that they all kind of blended together to make one whole section of time; as in the Renaissance era. It also helped me understand the time period in general a little bit better, as far as what was going on in history at the time as all of these astronomers were finding gravity and the solar system.

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Historical Astronomers in Context

Posted on February 6, 2024 by Leni Ertel

Johannes Kepler (1571-1630) was important to astronomy because he discovered that orbits are not perfectly circular, but move in ellipses. He is credited with three laws that are still heavily used in the study of astronomy. Kepler’s first law is: “The orbit of each planet about the sun is an ellipse with the sun at one focus.” Kepler’s second law is: “A planet moves faster in the part of its orbit nearer the sun and slower when further from the sun, sweeping out equal areas in equal times.” Kepler’s third law is: “More distant planets orbit the sun at slower average speeds, obeying the precise mathematical relationship p^2 = a^3.” (Bennett et al., 65-66). 

During Kepler’s lifetime, Britain became the rulers of the Atlantic Ocean. In 1588, Britain defeated Spain’s Armada, leading to Britain becoming a world-class power (History.com). Also during Kepler’s lifetime, Shakespeare began writing his plays. It is estimated that Shakespeare’s first play was written between 1589 and 1991 (Folger Shakespeare Library). Shakespeare took the theatre world, and the general population, by storm with his accessible, entertaining, and emotional plays. Shakespeare lived during the same period as Kepler, being born on April 26, 1564, and dying on April 23, 1616. He was revolutionary in literature and performance, and completely shifted the landscape of modern entertainment (Folger Shakespeare Library).

It is interesting to get more historical context on what was happening in the world while these major astronomical revelations were being discovered. This time period was huge in terms of shifting power dynamics and scientific revolutions. Kepler was just one person during a period where many people were making huge discoveries and observations about every aspect of our world. It made me realize that this period of time is importantly relevant and instrumental in informing us of the progress we have made, and how we can look back in time to these hugely influential people and learn from their creativity, intelligence, and vigor. 

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