One of the more mysterious subjects from our last reading was that of cosmic rays. To be quite honest, before encountering this in our textbook I had never considered cosmic rays outside of the context of the Marvel Universe. But it turns out that cosmic rays are more than just a cool-sounding superpower – these signals from the cosmos impact our daily lives and could provide exciting new information about the universe.
Cosmic rays are high-energy “fragments” of atoms (subatomic particles such as electrons, protons, or pieces of nucleus) that zoom through the Universe. Accepted scientific theory tells us that powerful cosmic events such as supernovae cause atoms to fragment into their constituent particles and shoot out across space.
Cosmic rays present a very interesting opportunity to scientists wishing to learn more about specific cosmic structures or events. Usually, the only information that the Universe offers us comes in the form of electromagnetic radiation. However, cosmic rays pose the opportunity for researchers to analyze matter that came (more or less) directly from these events. Although several ongoing efforts to interpret cosmic rays have made significant progress, the interpretation of cosmic rays remains mysterious.
However, scientists know a great deal about the effect of cosmic rays on our everyday activities here on Earth. Every second, we are being bombarded by cosmic rays that rain down through our atmosphere. Cosmic rays are the primary culprit for static/white noise on the radio and television. They are also to blame for many GPS and phone call errors. Yet these pesky particles effect more than our electronics. Some scientists believe that cosmic rays are responsible for genetic mutations and cancers. But cosmic rays aren’t all bad! In fact, can thank cosmic rays for the aurora borealis – the Northern Lights.
If you want to detect cosmic rays for yourself, I found a really cool DIY detector by Dr. Suzy Sheehie here.
Pulsars are some of the most interesting astronomical objects out there and are the subject of intense study by teams of scientists around the world.
Pulsars are rapidly rotating neutron stars that emit beams of intense energy from their magnetic poles. Here, it is important to bear in mind that a neutron star is actually the super dense remnant of a massive star, after said massive star has dramatically collapsed via supernova. These neutron stars (so called because they are composed almost entirely of atomic nuclei) possess a mass similar to that of our Sun, yet the radius of a typical U.S. city. In fact, the density of a neutron star is so great that one teaspoon of a matter from a neutron star would weigh many millions (maybe even billions!) of tons here on Earth.
It is important to note that while all pulsars are neutron stars, not all neutron stars are pulsars. A pulsar’s most defining property comes their rapid spin period. Many pulsars will complete over 500 full revolutions in one second! It is largely because of this insanely fast spin that the pulsars (composed of super-dense metals) exhibit extreme magnetic properties. This, combined with the fact that pulsars are surrounded by fields of charged particles, causes blasts of radiation to be emitted from the magnetic poles of the pulsar. Some neutron stars may not possess this spin rate or magnetic properties and thus are not pulsars.
Pulsars are most easily viewed from Earth using radio telescopes. These stars get their name because they appear to “pulsate” or “blink” every time that one of their magnetic poles hits Earth with a beam of electromagnetic energy.
Interestingly, pulsars are now being used to study gravitational waves! (This is a super interesting topic… maybe I will blog about it later!)
One of my personal favorite examples of archeoastronomy is Stonehenge, mainly because it is still such a mystery.
Originally built around 5,000 years ago, today we know very little about who, why, or how it was built. However, one thing that is clear that Stonehenge is aligned with the movements of the sun – many people speculate that could be a major part of the role it played as a perhaps a religious epicenter but the truth is we just don’t know. That’s what makes it so fascinating – if only we could go back in time and ask!
Space is vast. In fact, vast enough to contains many million, billions, and trillions of galaxies and other celestial objects. So the ultimate question is, how do scientists keep track of all of the celestial bodies? How do we know that the Andromeda galaxy is coming toward us if we can’t tell if it is growing in size by using naked eye observation? These burning questions, my friend, can be answered thanks to the rise of technology and advancements in practices.
From physics, we know that:
Velocity = Distance / Time
Therefore, if we were astronomers in the past, all we would have to do is determine the distance that a a star or a celestial object travels, and records the times at which we determined these distances, and, by subtracting the difference between the final and initial distance and final and initial time to find the velocity. For those of you who have taken calculus, this may look like:
Now that we have established what velocity is (and learned a bit of calculus), how is it that astronomers collect data on an object’s position in space?
In astronomy, there is something that is famously known as the Cosmic Distance Ladder. That is, given how far away an object or body is estimated to be, a certain method or device will be used to try and accurately gauge its distance. The distance ladder is shown below
If we look at the figure then we can see that, for example, we can accurately tell how far away an object in our solar system is by using RADAR and LIDAR. By using this method, scientists shoot radio waves into space and check how long it takes for them to bounce back. They then take the time and multiply it by the speed of light (since radio waves travel at the speed of light) to determine an object’s distance. So, if we really wanted to determine an object’s velocity in the solar system relative to us, we could use this technology to determine the distance away an object is to us at several different times. We would then use this to determine whether an object is moving toward or away from us, as well as how fast it is moving. If an asteroid is in the solar system, this could really help in determining whether or not it will strike Earth!
However, what happens when we just want to know velocity? Well, we look at a celestial object’s absorption spectra. An absorption spectra is all of the visible light that an object absorbs in space, thus why it is called an absorption spectra. The absorption spectra for the Sun looks something like this:
Those black lines tell us all of the wavelengths that our Sun absorbs. We can use these lines to then determine if an object is moving toward or away from us. If an object is moving toward us, the lines will all shift the same distance to the right. This is known as Redshift. If an object is moving away from us, then these lines move to the left the same distance. This is known as a Blueshift. We can then determine if an object has it’s spectral lines moved left or right by finding its absorption spectra when its not moving. Since elements each have their own absorption spectra, if we know the elements a object is made out of, then we can determine the absorption spectrum for that element when it is not moving. A visual example of red and blue shift looks something like this:
Finally, why does this shift in spectra even happen? Well, if you’ve ever heard an angry person honk their horn continuously while passing you on the freeway, you’ve probably experienced something known as a Doppler Effect. The Doppler Effect essential states that anything wave at a velocity greater than 0 relative to you will slightly bend. Thus, when that person passes you, the sound waves get bent and the sound gets distorted. There is a great video by altshift that explains this better visually. Therefore, since light is a wave, light that is moving toward or away from us will become distorted and essentially change in wavelength. Thus, that is why we see the shift in wavelength to the left or right with Redshift and Blueshift.
Note, however, that objects on Earth move too slow for us to see this distortion of light. However, we can still hear distorted sounds thanks to the Doppler Effect. And so, I leave you with this: Video on Doppler Effect Using Trumpets
The existence of dimensions beyond the three spatial and one temporal we experientially inhabit in our current model of spacetime has been a longstanding discussion touched on by various physicists and the scientific community. It has been suggested that gravity would propagate throughout these other dimensions, a thought brought about in attempts to somewhat unify aspects of quantum theory and general relativity, and explain the apparent “weakness” of gravity. The detection and measurement of gravitational waves paved the way for last year’s proposal that anomalies in detected gravitational waves could suggest the existence of extra dimensions. Given the assumption that gravity interacts with extra dimensions, gravitational waves would similarly interact with these dimensions were they to be present. The idea is that if there are extra dimensions that gravitational waves are interacting with, this interaction would be a detectable phenomena by means of calculating the anticipated strength of the waves given their source and their strength once they reach the detector. An unexpected measurement in the strength of the gravitational waves would provide evidence for extra dimensions “stealing” and therefore weakening the waves over distance.
This hypothesis was promising, however earlier this year observations from two colliding neutron stars were used to compare expected and measured strengths of gravitational waves in search of and leakage that would have occurred, causing a reduction in wave amplitude. The strength of detected gravitational waves given their distance was as expected, meaning no measured leaking took place to suggest the presence of large extra dimensions. Despite this result, there still remain extra-dimensional theories to be tested.
For more information on the significant connection between the strength of gravity (mainly how weak it is) and the possibility of extra dimensions, I found this video to be extremely informative and easy to understand.
Plato believed that our senses could not be trusted to reveal the truth of the Universe. He argued that the world around us was an imperfect representation of the ideal world, our perception put before us by our faculties – simply shadows cast from imperceptible forms. Cognizance of truth was achievable only by means of reasoning through the employment of one’s intellect.
The thought of being unable to trust one’s senses to show the truth of reality was suggested to result in the death of the philosopher. People do not want to hear that they have been living a lie, that everything they know is not the true nature of reality. The upheaval of one’s beliefs, identity, and entire worldview must cause them strife, anger, and lead to violent opposition and denial, according to Plato’s writings. However behind our perception of reality, the search for the true nature of the Universe and the pursuit of science is for the most part now welcomed with excitement and wonder. The abstract nature of light brings some truth to Plato’s fundamental belief. While most are familiar with the what light does in their daily interaction with it, our perception alone by our senses does not bring us to a full understanding of the truth. While early thinkers believed sight was the product of our eyes emitting rays which bounced off those things looked at and returned to us, our modern understanding of light reveals it as information carried by electromagnetic energy. Exhibiting properties of both a wave and a particle, photons are packages of light that carry radiative energy and are characterized as waves are, by wavelength and frequency. Visible light is only a small fraction of the information carried in the electromagnetic spectrum, and it is easy to see how ignorance of this would lead to the conclusion that the light we perceive through our senses is all there is. However there is a vast field of information all around us and throughout the Universe that we are unable to detect without the aid of modern instruments. To fully understand the nature of the Universe, the capacity to recognize, receive, and decipher the ways in which it communicates information to us in its entirety is essential.
It’s no secret that the universe is growing. However, research leads us to believe that our own Milky Way Galaxy is growing as well. In fact, our galaxy exhibits cannibalistic behavior, absorbing material from the dwarf galaxies surrounding it. We know that the chemical makeup in the central bulge of our galaxy differs from the chemical makeup of the outer halo of our galaxy, and we have also found that the chemical makeup of the outer halo of our galaxy is similar to the chemical makeup of stars found in dwarf galaxies orbiting our galaxy – namely, the Large Magellanic Cloud and the Sagittarius Dwarf Elliptical Galaxy. Therefore, these dwarf galaxies may simply be the leftovers of galaxies that were long ago absorbed into our own galaxy.
Astronomers believe the key to understanding the growth of our galaxy is learning more about the dark matter around our galaxy. The halo of dark matter surrounding our galaxy actually exerts a gravitational force on smaller, neighboring galaxies, so it may be that dark matter is ripping away stars and pulling them into the external regions of our galaxy. There are still so many unanswered questions about dark matter and dark energy, but a project called the Dark Energy Survey is currently underway, in which we are using a tool called the Dark Energy Camera to detect stellar streams. Stellar streams are groups of relatively few stars that have been ripped away. They are difficult to detect because we are looking for a small number of stars in such a large region of space. Nevertheless, these stellar streams illustrate how our galaxy is constructed from smaller galaxies, so the future findings of the Dark Energy Survey should prove exciting!
We’ve all seen and learned about the cosmos and the stars up above. We learned that the Earth revolves around the Sun because the Sun’s force on the Earth is greater than any of the other major celestial bodies near this. However, something that many people forget is that this process is facilitated by Newton’s Universal Law of Gravitation.
In terms of the realm of physics, Newton describes the Universal Law of Gravitation as:
F12 = G
Now, I understand that the physics formulas can be a bit daunting, so let is break this down. First, let us define the variables in this formula:
F12 = Force exerted by one body on another
G = The Gravitational Constant (for those technically inclined, this number is 6.67408 × 10-11 m3 kg-1 s-2)
m1= Mass of one of the bodies
m2= Mass of the other body
r2= distances between the center of each body, squared
Okay, so now that we know what the equation means you’re probably asking
“Okay, so now I know how the force between two bodies is measured. What does that have to do with anything?”
Well, this is important because this clears up a common misconception in people’s minds about gravity and attraction, especially in space. Let us say that, for example, m1 is the mass of the Earth, m2 is the mass of the Sun, and r is the distance between the sun and the Earth. Then, our Law of Gravitation Equation would look something like this:
This formula is then saying that, if we had all of these values, then we would know the gravitational force that the Earth exerts on the Sun. Now, let’s switch it around. Let’s say m1 is the mass of the Sun, m2 is the mass of the Earth, and r is STILL the distance between the sun and the Earth (in other words, r has NOT changed). Then, the force that the Sun exerts on the Earth would be characterized by:
Now, if we employ our first grade multiplication rules (the Commutative Property of Multiplication), we notice that both forces are equal! Yes, this means that the force that the Sun exerts on the Earth is EQUAL to the force the Earth exerts on the Sun. This is important because it proves false the common misconception that more massive things pull stronger on an object than less massive things. We see that, by using the Universal Law of Gravitation, this is false. Therefore, we can conclude that all objects that attract each other exert an equal force on one another.
Now, this also generalizes to smaller objects as well. Yes, humans have a gravitational attraction to their phones just as their phones are gravitationally attracted to them. However, the force of this attraction is so weak that we simply do not notice it. This Veritasium video does well in explaining the mathematics behind this. However, now that you know this this means that the pasta you attracted toward your face for dinner had an equal gravitational attraction to you. And, for those of you looking for a Valentine, you can now be certain that your crush is equally attracted to you as you are to him or her (at least concerning gravitational attraction).
The Trump administration’s NASA budget request for 2019 was revealed today, and many of the requests come at the dismay of many prominent people in the space and astronomy field. Most of the requests call for NASA to pursue commercial partnerships. For example, the administration requests NASA stop directly funding the International Space Station (ISS) by 2025, urging them to find commercial partnerships with private companies and other countries to fund the satellite. The budget allocates an extra $150 million to NASA to start a program to get more commercial companies involved in low orbit Earth projects. Many have spoken about the funding cuts of the ISS, saying that America should not leave its main post in space as the boundaries of our knowledge of space are being pushed.
The Trump administration also wants NASA to focus on sending humans back to the Moon. However, the budget does not allocate enough funds or detail enough plans to make lunar ambitions feasible at this point. Instead, the budget again requests that NASA look toward commercial rockets for moon landings and other projects. While focusing on sending humans back to the Moon, the administration requests the shutdown of five Earth Science missions, one of which is the WFIRST telescope. This telescope gives scientists the ability to study dark matter and exoplanets. NASA’s Education program, which funds grants and scholarships for students, is also on the chopping block. The budget requests that this sector be completely cut, but Congress defied this request last year, making sure the program still received funding. We will have to stay tuned to see what components of this budget actually get confirmed.
The privatization of space missions is a multifaceted problem. Privatizing something means that the people investing in said thing would need a way to gather profit. When dealing with a thing such as space, where is there a profit to be made? Space exploration is done because people believe it is a necessary good. As humans, we are naturally curious and want to know more about the space we inhabit. By privatizing explorations, companies could essentially restrict what is being learned and who is learning it. As the budget is reviewed and finalized, I hope people will see the many caveats of turning space into a private venture.
We’ve talked a bit about black body radiation and how some stars appear more reddish or bluish, or maybe even just white. But how and why do stars appear as more reddish or bluish, and why are some stars larger than others? What makes Red Giants and White Dwarfs special? Well, it all has to do with the life cycle of stars as they burn through the Hydrogen and eventually other fused elements that make them up (around this time they become Red Giants) until they run out of fuel and either disspate into a White Dwarf surrounded by a planetary nebula or explode in supernova and either become Neutron Stars or, in the case of extremely large stars, black holes.
We know even more about stars than just their life cycles though – Ejnar Hertzsprung and Henry Norris Russell worked in parallel studying dwarf and giant stars, determining that there was a relationship between the mass and luminosity of a star and its color. This research was later used in the creation of the modern Hertzsprung-Russell Diagram, which plots stars according to their temperature and luminosity relative to the sun.
Stars in the Main Sequence are generally in the process of fusing their supply of Hydrogen. Stars on the Main Sequence range from Red Dwarfs, which fuse hyodren extremely slowly and are expected to stay on the main sequence for about 2.5 trillion years before becoming blue dwarfs. Massive stars on the Main Sequence are generally blue, while stars like the Sun waver in the middle of the main Sequence and emitting white light. Stars that are less than a quarter the sun’s mass will die peacefully by turning into white dwarfs, while more massive stars will turn into dimmer but larger Red Dwarfs. Stars much larger than the sun, such as Blue Giants, get their color from their extreme temperature compared to the sun.