Light and the Electromagnetic Spectrum – Blog 2 – Cameron Klein

Posted on February 12, 2024 by Cameron Klein
HubbleSite

Before enrolling in this course, I had given no thought as to what light truly was. To me, light simply stemmed from the light switch on my wall as I flicked it on and off. However, there is so much more to light than what first meets the eye (no pun intended). According to the The Cosmic Perspective by Jeffrey O. Bennett, Megan O. Donahue, Nicholas Schneider, and Mark Voit, Newton correctly inferred that light was made up of tiny particles, though he didn’t know quite what. The first component of light that I would like to highlight are waves. There are many types of waves, including radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays. All of these waves have different properties, and some are visible to the naked eye, while many are not. Waves are often characterized by their peaks (uppermost parts) and troughs (lowermost parts). However, although waves move outward, the particles within them move up and down. Another term important to the conversation of waves is wavelength. Wavelengths describe how long a specific wave is by illustrating the distance between peaks and troughs. Additionally, frequency is characterized by the number of peaks passing by any given point each second. Then, when we multiply wavelength by frequency, we get speed. The speed of waves is the distance that the waves traveled in a specific amount of time.

Now that you have a decent groundwork for what light is, we can begin our discussion of the electromagnetic spectrum. The range of colors that we can see with our eyes is only a tiny part of all of the light in the universe…or, in other words, the spectrum of light. Hence, the use of the term: electromagnetic spectrum. Though it is difficult to fully grasp, there is light beyond the rainbow that we are unable to see. The form of light in which we are able to see is dubbed visible light. Virtually, these are the colors of the rainbow. Colors between about 400-700 nanometers make up the colors of the rainbow. Light with wavelengths of just beyond 700 nanometers (what we see as red) are called infrared light. Just beyond infrared light are microwaves, and then we move to radio waves, which are the longest wavelength-light. Then, moving along the spectrum in the other direction, if a light is just shorter than 400 nanometers, it is considered ultraviolet light. Ultraviolet light can be extremely damaging, causing sunburn and even skin cancer. Light with shorter wavelengths are x-rays and the shortest wavelength-light are gamma rays. I hope that this helped to lay the foundation of light and the electromagnetic spectrum for you!

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Ancient Structures

Posted on February 12, 2024 by Maddy Pollard
Stonehenge

Many people have heard about Stonehenge, one of the world’s most famous monuments. But did you know that the circle of stones was actually an astronomical device? Archeoastronomists have debated what the original purpose of Stonehenge was, but many believe that it was used to mark solar and lunar alignments, including eclipses, solstices, and equinoxes. Many other ancient cultures built structures for astronomical purposes. Another famous example is the Templo Mayor, built by the Aztecs in modern-day Mexico City. This structure was built so that the Sun would rise right in between the two temples on the equinoxes. A third famous structure is the Sun Dagger, which is found on the Fajada Butte in New Mexico. This special structure, made up of three slabs of rock leaning against a cliff, show different patterns of light based on the time of year. For example, sunlight shines through the rocks and produces a single “dagger” on sunlight only on the summer solstice. These structures were a way for ancient civilizations to mark special dates, such as solstices and equinoxes, as well as keep track of the seasons. It’s interesting to see the different structures each ancient civilization thought of to measure the same astronomical events. Unfortunately, many of these ancient structures have either shifted or been destroyed and no longer serve their original purpose. They are still cool to learn about though!

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Justin's Blog 2024-02-12 17:22:51

Posted on February 12, 2024 by Justin Kim

History of Astronomy in Korea!

Hey everyone !

Do you guys remember when we were learning about historical astronomical sites in class? I remember one of the sites catching my eye because it looked incredibly familiar. It was the one in Korea called Cheonseongdae in Gyeongju, South Korea. I once visited this while on a trip with family and friends when I was much younger but seeing it again sparked so many memories. Learning about how old it is amazed me because its so well preserved.

This astronomical site is considered to be one of the earliest in East Asia (maybe the entire world). It is believed to have been constructed in 647 C. E. This observatory may have been used to make astronomical observations to plan agriculture. There is a lot of disagreement around Cheonseongdae because there is no clear documentation about how it was once used. Some believe that this site is simply an altar to pay tribute to the god of agriculture. This is like the Stone Henge of Asia.

Source: Cheonseongdae

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A tidal bore worth traveling for

Posted on February 12, 2024 by Angela Harris

Mont Saint-Michel at high tide

Chapter 4 of the textbook explained how the Moon and the Sun affect ocean tides. We learned that the timing and height of tides at a given location depends on its latitude, the orientation of the coastline, and the depth and shape of any channel the tide has to flow through. The book gave an example of a location with an unusual tidal pattern; the incoming tide at the abbey of Mont Saint-Michel in Normandy, France.

The difference between low and high tide at Mont Saint-Michel is up to 15 meters which makes it one of the highest tides in Europe! The tide rises faster than people can swim, but many kayakers enjoy the strong current!

If you were planning a trip to Mont Saint-Michel to see the impressive tidal bore, you would want to consider a few factors. Since it is a spring tide, you would want to visit during the New Moon or Full Moon (the strongest tide is usually 36 to 48 hours after). You could also use this tide forecast to pick the best day, time, and viewing site! Would you travel to Mont Saint-Michel or any other famous tidal site to see the tidal bore in person?

Kayakers enjoying the strong current in the Mont Saint-Michel Bay!

Other source: Textbook chapter 4

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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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