Black Holes Emitting Light?

Posted on March 3, 2024 by Andres Becerra

Take a look at this picture of a black hole

Photo by: Space.com

This is actually called a quasar. A quasar is a supermassive black hole that is actively pulling in surrounding material due to its massive gravitational force. A black hole is an entity where the force of gravity is so intense that not even light can escape it. But wait? There is literally light coming out of the black hole in the picture I just showed you. And I just said light can’t escape a black hole. So how is that possible?

Let me tell you

Not every black hole produces a light beam (called a quasar jet) that we can see. The light coming out of a quasar isn’t actually coming from the black hole. There are a couple factors that need to be met before this light beam can be produced and seen. The factors that need to be met is the supermassive black hole needs to be spinning rapidly and it needs to have a black hole corona emit large amounts of X-rays. A black hole corona is the area on top of and below the material we see spinning in a circle around the black hole. The black hole coronas emit a ton of X-rays and create an extremely powerful magnetic field. The strong magnetic field along with the X-rays and the speed of rotation allow the quasar jet to stay in place and to be seen without it being sucked in by the black hole. The quasar jet is not inside of the black hole and remains in its location mainly due to the magnetism created by these factors.

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From collapse to solar system

Posted on March 3, 2024 by abbieychen

Once upon a time, there was a huge interstellar cloud of cold, low-density gas called the solar nebula. This solar nebula came about from billions of years of galactic recycling, and consists of about 98% hydrogen and helium and 2% other random elements. The solar nebula collapsed under its own gravity, and BOOM! the Sun and planets were born!

After the solar nebula went through its initial gravitational collapse, three things happened that shaped it into what our solar system is like today.

First, the solar nebula heated up. Its heating represents energy conservation! As the cloud was collapsing, the cloud became smaller in size due to all the gas particles movements. As gas particles kept on crashing into each other, their kinetic energy was converted into thermal energy. Eventually, our Sun formed in the center, where temperatures and densities were the highest.

The solar nebula also spun faster and faster as it got smaller in radius. The spinning represented conservation of angular momentum. The rotation of the solar nebula allowed everything to be well distributed throughout, which is how we ended up with objects everywhere in our solar system.

Finally, the solar nebula flattened out. It started out as a spherical shape, but with the spinning of the cloud and particles colliding, the gas collide and merge together. Because of conservation of momentum, each collision results in the new clump of gas having the same average velocity as all the molecules together. This kept happening, until the entire cloud flattened. This led to the elliptical planetary orbits being in roughly the same plane, and in the same direction.

The Solar System’s glowup!! (Image credit: olemiss.edu)

Now, our solar system is all grown up!! Our planets happily orbit around the Sun. Everything that the solar nebula went through resulted in the orderly fashion that our planets and other objects orbit and rotate.

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Blog 3: Nuclear Fusion

Posted on March 3, 2024 by Nicholas Fleisher

The sun is the greatest, most massive, hottest thing in our world. But how does it even work?? I’m gonna be totally honest, I’m not a big science guy so I’ve never really had the change to answer this question. But Chapter 14 gives us an in depth explanation of how the sun functions through the process of nuclear fusion.

When the sun was born 4.5 billion years ago from a collapsing cloud of interstellar gas, a contraction of the cloud released enough gravitational potential energy to raise the interior temperature and pressure of the sun. This process of gravitational contraction is similar to how a shrinking gas cloud heats up because gravitational potential energy of the gas particles far from the center of the cloud is converted to thermal energy as gas moves inward. The process continued until the core finally became hot enough to sustain nuclear fusion! At that point, the Sun produced enough energy to give it the stability it has today. Through this process of nuclear fusion, the sun converts mass into energy. This is based off of Einstein’s theory of relativity, which is that mass itself contains more than enough energy to account for billions of years of sunshine, so the sun shines if it can convert some of its mass into thermal energy. The sun was born with enough fusion to last about 10 billion years, so since we are about halfway through that point, in 5 billion years when the sun exhausts its nuclear fuel, the gravitational contractions will begin again and the cycle will repeat.

The actual process of nuclear fusion on an atomic level can be thought of as the combining or fusing of two or more small nuclei into a larger one. This is the opposite of nuclear fission, which is the process of splitting an atomic nucleus. Nuclear fusion happens when nuclei are colliding with enough sufficient energy that they can bind protons and neutrons into an atomic nuclei (so that it can overcome the electromagnetic repulsion between the positively charges nuclei). It’s important for the temperature to be high so that the nuclei collide at very high speeds to fuse. The process of proton-proton fusion is what mostly occurs in the sun. This is when two protons fuse to form a nucleus consisting of one proton and one neutron. The nuclei collides and fuses with a proton, resulting in a nucleus of Helium-3 (a rare helium with 2 protons and one neutron) and a gamma-ray photon. Then, another neutron is added to H3 to make H4, which occurs through the collision of two H3 nuclei. The result is a normal H4 nucleus and 2 protons. This fusion of hydrogen into helium generates energy because helium nucleus has a mass slightly less than the combined mass of four Hydrogen nuclei. Overtime, the total number of independent particles in the solar core gradually decreases and this gradual reduction causes the solar core to shrink. Further, the gradual increase in core temperature and fusion rate keeps the core pressure high enough to counteract the stronger compression of gravity.
For the energy produced by fusion to actually escape the sun’s core, it moves slowly through the radiation zone through randomly bouncing photons, gets scurried upward by convection in the convection zone, and then moves through the photosphere at the top of the convection zone, where density of gas is low enough that photons escape to space. The energy built up from long before in the solar core finally emerges from the sun as thermal radiation, which is how the sun shines!

Video Source: How The Sun Shines

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The Sun

Posted on March 3, 2024 by Maddy Pollard
The Sun

The Sun is arguably the most important thing in our solar system. It is the orbital center for each planet, and allows for life to be sustained on Earth. But what actually is the Sun?

The Sun is a giant, glowing hot ball of gas that actually has many layers to it. The outermost layer of the Sun’s atmosphere is the corona, which is made up of a low-density gas that has a really high temperature. This region emits most of the Sun’s X rays, and extends several million kilometers above the Sun’s visible surface!

The next layer is the chromosphere, which is the middle layer of the solar atmosphere. The chromosphere radiates most of the Sun’s ultraviolet light—you can thank this region for needing to wear sunscreen!

The photosphere is the lowest layer of the solar atmosphere and the visible surface of the Sun. The Sun doesn’t actually have a solid surface like we have on Earth, but the photosphere gives the illusion of a surface, even though it is made up of a gas far less dense than that of Earth’s atmosphere. The photosphere is also where sunspots are found, which are darker, cooler spots on the Sun’s “surface.”

Inside of the Sun we find the convection zone. This is where energy from the solar core travels outward, transported by the rising of hot gas and the falling of cooler gas. This zone is why the Sun appears to have a seething, churning, and bubbling surface. 

Further inward is the radiation zone, where energy moves outward primarily in the form of photons of light. Photons in this zone bounce around in a zigzag motion that very gradually allows it to move outward. 

Finally, we reach the solar core, the innermost point of the Sun. This is the source of the Sun’s energy, where nuclear fusion occurs. The temperature of the solar core is about 15 million K, and the energy produced takes hundreds of thousands of years to reach the photosphere!

So while the Sun may appear to be just a glowing ball of fire in the sky, it is actually much more complex! Next time you are out enjoying the warmth of the Sun, think about all of the processes that allow our Sun to shine.

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Spacecraft

Posted on March 3, 2024 by Maddy Pollard
Apollo 11 Spacecraft

Our solar system is full of many mysteries, and spacecraft are one of the main ways we can gather information about it. There are four types of robotic spacecraft: flybys, orbiters, landers and probes, and sample return missions. 

Flybys travel past a world only once, and then continue on their way into space. Because of this, they offer a relatively short period of close-up study of a world. Orbiters do exactly what they sound like, orbit the world they are visiting. Their continuous orbit allows a much longer period of close-up study compared to flybys. Landers and probes are designed to land on a planet’s surface or probe a planet’s atmosphere by flying through it. These types of spacecraft allow for the most close up study of other worlds, because they actually come in direct contact with the planets! Sample return missions are the final type of spacecraft, and they make a round trip from Earth to the world they are visiting, and then back to Earth. Think of the Moon as the most common sample return mission, that is how we have Moon rocks on Earth!

Spacecraft are often a combination of these four main types. Take the Apollo missions for example, they were both landers and probes (because they landed on the Moon), and sample return (because they came back to Earth). Spacecraft are extremely important for the exploration of our solar system, it will be interesting to see what kinds of missions are launched in the future!

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Blog 4: Space Telescopes

Posted on March 3, 2024 by Charles Knoll

Telescopes play a pivotal role in deepening our understanding of the universe. While many telescopes are positioned on Earth, those placed in space afford us a more profound insight into the universe. Stationed beyond the Earth’s atmosphere, space telescopes capture clearer images of the cosmos. The Earth’s atmosphere, which blurs images and only permits radio waves and visible light to reach the surface while blocking gamma rays, ultraviolet light, and X-rays, restricts our view of the entire electromagnetic spectrum. This limitation hampers our ability to fully comprehend the universe. Space telescopes, enable astronomers to study the universe across the full spectrum of electromagnetic light, revealing cosmic mysteries that are concealed from ground-based observatories. Nevertheless, the benefits of space-based observation come with higher costs for construction and maintenance compared to their Earthly counterparts, posing significant economic challenges to further space studies. 

Source: Image

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Blog 3: Our Sun and Nuclear Fusion

Posted on March 3, 2024 by Charles Knoll

The sun releases energy through a remarkable process known as nuclear fusion, which unfolds under the extreme temperatures and densities found deep within its core. Unlike the nuclear fission reactions used on Earth, which split atomic nuclei to release energy, the sun’s energy is generated by combining smaller nuclei into larger, heavier ones. This fusion process is possible because the sun’s core is a plasma with temperatures around 15 million Kelvin, anything colder and it would be a lot harder for nuclear fusion to occur. Within this intensely hot core or “soup” of gas, positively charged nuclei move at incredibly high speeds, occasionally colliding and combining to form larger nuclei. The key to nuclear fusion lies in pushing positively charged nuclei close together to allow the strong force to overcome the electromagnetic repulsion. This process not only powers the sun, giving it its brightness and warmth but also serves as a fundamental difference between the nuclear energy engineered by humans on Earth.

Sources: Photo, Nuclear Fusion

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Blog 4: Explaining Relativistic time dilation

Posted on March 2, 2024 by matthewastro

Time seems to be one of the only immutable aspects of the universe, besides death and taxes. Many people believe that the passage of time is altogether unstoppable and unyielding. And for most intensive purposes, they are right. Indeed, time is our most precious resource and one that many of believe we have an extremely solid understanding of, accumulated over years and years of lived experiences. With this said, the vast majority of people have an incomplete understanding of time. Time is not absolute. It is relative. For most of human history, time was understood to be distinct from the geographic dimensions often understood to comprise space (and therefore the fabric of our universe). After many developments in physics (and especially Einstein’s formulation of Special and General Relativity, we now understand that space and time are unified as one fabric which we know as spacetime. An object’s position in space is defined not only by its situation on specific geographic coordinates (such as x, y and z) but also by its place in time.

A diagram depicting the gravitation warping of spacetime by a massive object. By “Pk0001” on Wikimedia Commons.

Einstein’s relativistic discoveries tell us that massive objects warp the fabric of space in towards them, distorting the path of all substances (even light and neutrinos interacting with them. Normally, all particles will travel along a straight line in the direction of whatever net forces originally propelled them along (unless they are acted upon by). When interacting with the gravitational field of a massive object, however, particles will be subjected to the curvature exerted by the object, changing their direction. The concept of “local time” is absolutely essential for understanding time dilation. An object’s status in the universe is defined by its situation on the fabric of the universe (spacetime). An object travelling in a straight line (at speeds not close to the speed of light), will experience time at an essentially normal rate, whereas the same object influenced by a massive gravitational field will cover less “distance,” or spacetime. Outside observers would see time slow down for the object negotiating the gravitational field, while “their” time would still pass normally.

A similar effect happens when approaching the speed of light. Special Relativity (and the equivalence principle of General Relativity) tells us that the speed of light is constant in all reference frames (inertial and otherwise). Newtonian (and classical) physics would have us intuit that the speed of light was not constant due to the addition of velocities when measuring (or perceiving) the speed of another object. Consider an observer running in a straight line while they observe an object parallel to their velocity vector travelling at near light speed in same direction. Classical physics would require the observer to subtract their speed which theoretically causes them to “catch up” to the object travelling near the speed of light. The constancy of the speed of light (and by extension speeds very, very close to it in the context of the addition of velocities) means that the classical intuition is incorrect. Relativity tells us that objects moving near (or at the speed of light will increasingly distort the spacetime around them in a similar way to how massive objects curve spacetime towards them. This similar phenomenon affects how local time is perceived by outside observers, with curving making it seem as if the fast-travelling object is negotiating less spacetime.

While our perception of time (and even the passage of time) can be altered in very specific circumstances, our temporal existence is largely immutable. That is to say: live a life without regrets! We currently cannot reverse time (and may never be able to, especially under our current scientific understanding), so we must make the most of the many opportunities we are afforded. We must use our one chance at life wisely.

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Blog 3: Equilibrium and the stability of earth

Posted on March 2, 2024 by matthewastro

The formation of Earth and its current sustainability as they only known life-sustaining body in the universe have been caused by a number of extremely specific conditions which combine to make our planet the only one on which life is known to thrive. In this post, I will survey two of the specific conditions on Earth which allow life to thrive (tectonic activity and the greenhouse effect) and examine their historical causes through an astronomical lens. This survey of conditions is intentionally not exhaustive. Instead, this survey will give a deeper appreciation for some of the conditions that allow us to exist. We should take care to appreciate the extreme “luck” that allows us to exist here, in our seemingly lifeless universe, and thus realize the uniqueness of our home.

Tectonic activity is a fundamental component of Earth’s geology and it is essential for sustaining life on Earth. One extremely significant consequence of tectonic activity is the formation of volcanoes (and volcanic eruptions). Volcanic eruptions allow the Earth to release “geological stress” by creating an upwelling of magma through pressure that is then released on the lithosphere in an eruption. Although eruptions are very often harmful to life in the short-term, they mediate weather with reflective ash and enrich soils. Eruptions are often responsible for ecological succession, where existing forests are damaged or destroyed by volcanic eruptions, which enrich the soil in the medium to long-term by depositing ash and recycling nutrients into the ground. The emerging forests are more ecologically resilient (and biodiverse) compared to the forest that existed before the eruption. Volcanic activity is likely responsible for taking Earth out of its most recent “snowball” phase (approximately 600 mya), during which oceans were very widely covered by ice (and therefore not releasing substantial carbon dioxide into the atmosphere and sustaining a greenhouse effect). Gradually, outgassing from volcanoes is believed to have released sufficient carbon dioxide into the atmosphere to restabilize temperatures on Earth. Thereafter the biodiversity of life increased tremendously in the Cambrian Explosion, a central event that has preceded the wide diversity of life on Earth in relatively recent geological history.

A depiction of snowball Earth. By “guano” on Flickr. Image courtesy of Cornell University.

The greenhouse effect has been essential for sustaining temperatures that are conducive to the continued existence of liquid water and the subsequent life that has existed on Earth. Greenhouse gases, which exist in relative abundance in Earth’s atmosphere (such as ozone, water vapor and carbon dioxide). Earth’s early atmosphere was rich in carbon dioxide, methane and water vapor, which absorbed and reemitted heat (which would have otherwise been lost into space) back onto the surface of the Earth. While this was happening, photosynthetic microorganisms were actively producing oxygen, which accumulated in the atmosphere over approximately one billion years. The proliferation of oxygen has given rise to nearly all existing life today, particularly by facilitating the presence of ozone (a reactive molecule with three oxygen atoms) in the stratosphere (part of the “upper” atmosphere. The reactive ozone “layer” absorbs solar ultraviolet light, which would otherwise reach the surface and significantly damage existing life on Earth. Relatively stable temperatures have proven to be essential for life’s resilience even in the most trying of times, and will remain essential for life’s continued existence on Earth.

Both the greenhouse effect and plate tectonics have proven absolutely essential for our incredible world, but they exist among other essential patterns (such as rotation and the magnetosphere) that work cohesively to sustain life on Earth. By understanding the uniqueness and importance of the processes which sustain our world, we only stand to gain more appreciation for the work we must do to maintain conditions that can sustain life for our generation and those to come.

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Geology of the Moon and Mercury – Blog 4

Posted on March 2, 2024 by Cameron Klein
Temple University

After writing my last blog post about atmospheres and the greenhouse effect, when learning that the atmospheres of the Moon and Mercury cause them to be considered practically airless and have no weather, I became heavily intrigued. What makes the Moon and Mercury so different from the other planets in our solar system? Thus, I delved into my investigation.

Some important features of our Moon are what we can differentiate from Earth as the bright portions of the Moon and the smoother, darker ones. The lunar highlands are what we see as the lighter portion of the Moon, and the lunar maria are the darker portions. Within the lunar maria, astronomers have examined very interesting volcanic and tectonic activity. When crashing planetesimals were abundant in our solar system, the heaviest impacts on the Moon were so violent that they were able to penetrate and crack the Moon’s lithosphere and make large craters. However, the Moon built up extreme amounts of heat inside of it over billions of years that molten rock fled through the cracks of the lithosphere and filled up these craters! However, now that impacts of craters into planetary bodies are not nearly as common, we typically only see sandblasting on the Moon’s surface by micrometeoroids. If you do not what a micrometeoroid is, they are just small pieces of rock or metal that broke into Earth’s atmosphere. These micrometeoroids slightly break down the surface of the Moon, thus explaining why the Moon is covered with dust!

Now, we move on to the geology of Mercury. Just like on the Moon, impact craters are extremely common, but the fact that they are spread out suggests prior volcanic activity on the planet! This is because the lava from volcanoes would have filled in craters to make them appear smooth. If you were to observe Mercury through a telescope, you may see an enormous crater called the Caloris Basin, and this resulted from an extremely large impact that melted surface rock that then melted into the crater. As Dr. Grundstrom pointed out in class, Mercury has an atypically large core compared to the sizes of other planets. This is due to the fact that Mercury retained more heat from accretion (when small particles grew into planets) and differentiation (when higher densities sank and lower densities rose) — this caused Mercury’s core to enlarge. Now, however, Mercury is confirmed to be geologically dead.

Studying the geological makeup of these two planets was extremely rewarding for me, and I hope that you all enjoyed learning about them, as well!

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