The aurora is a natural phenomenon that has fascinated both scientists and the general public for a long time. When charged particles from the Sun collide with the Earth’s magnetic field and atmosphere, it leads to the emission of colorful light in the sky. However, the aurora is not just an aesthetically pleasing sight but also a scientific puzzle that has yet to be fully understood.
Despite considerable progress, many mysteries about the aurora remain unsolved. One theory posits that the Earth’s magnetic field plays a crucial role in determining the shape of the aurora, while other research investigates the impact of turbulence in the Earth’s magnetosphere and solar wind on the aurora’s movement.
Moreover, the aurora’s study is not limited to scientific curiosity, but it has practical applications as well. Auroras can significantly disrupt communication systems, power grids, and satellite operations in high-latitude areas. Consequently, further research is crucial to developing strategies to mitigate these impacts and safeguard our infrastructure. In conclusion, the aurora is a complex and captivating natural phenomenon that requires more research to uncover its secrets and mitigate its effects on our technology.
The Solar System is an extraordinary marvel of the universe, a collection of celestial objects that has captured the curiosity of scientists, and the imagination of people for generations. The composition of these objects holds vital clues to understanding the origins of the Solar System and the processes that have shaped it over billions of years. From the rocky planets to the gas giants, each object in the Solar System has a unique story to tell, a testimony to the remarkable diversity of our cosmic neighborhood.
The four inner planets are a testament to the immense forces at work in the early Solar System. As the solar nebula cooled, particles began to clump together, forming larger and larger objects that eventually gave rise to the terrestrial planets. These rocky worlds stand in stark contrast to the gas giants, which formed in a colder and more volatile region of the Solar System. The outer planets are the result of the gravitational capture of vast amounts of gas and ice, creating the magnificent giants we see today.
The small bodies in the Solar System, such as asteroids and comets, are remnants of the early Solar System that offer a glimpse into its tumultuous past. These objects contain valuable information about the conditions and processes that existed during the formation of the Solar System, shedding light on the mysteries that still baffle scientists today. By studying the composition of these small bodies, we can better understand the evolution of the Solar System and the many wonders that it contains.
Energy from the Sun carried through the magnetic field! Image from NASA’s TRACE Project
Have you ever wondered why the sun shines?
It’s a question that has inspired centuries of astronomers to come up with a wide variety of explanations. It was once thought that the sun shone because of chemical combustion, but we now know that there is nowhere near enough oxygen for that process to have sustained the sun for as long as it has been burning, only enough for a few thousand years. This is credited as having come from the Greek philosopher Anaxagoras, who believed that the sun was a red-hot stone.
“Everything has a natural explanation. The moon is not a god but a great rock and the sun a hot rock.”
Today, scientists are certain that nuclear fusion is the process driving the sun’s energy production!
Nuclear fusion occurs when two light nuclei combine together to form a heavier nucleus and some energy. In the case of our sun, it is powered through hydrogen fusion (AKA the combination of two Hydrogen to create one Helium + energy).
Inversely, there is a process known as nuclear fission in which an atom is split into smaller nuclei; this releases an incredible amount of energy, and is the source of much power for technology from vehicles all the way to destructive atom bombs. Scientists’ ability to harness the power from both fusion and fission is greatly increasing, but poses a major threat if it were to fall into the wrong hands.
It’s no secret that our planet is in the midst of a global climate crisis– rising sea levels, compounding greenhouse gas emissions, and depleting natural resources have left our environment at a very real risk of collapse, endangering all living creatures on our planet.
When studying astronomy, it becomes easy to lose focus on the planet that we live in in favor of seeking knowledge about the ones we cannot step foot on. Still, it is incredibly important that we don’t lose sight of our immediate environment, instead pursuing information in tandem.
Astronomy and environmentalism are not as disconnected as one might think. In fact, recent estimates approximate that the space sector is responsible for 1.2 million metric tons of carbon dioxide released into the atmosphere every year!
When studying astronomy, we also become increasingly aware of Earth’s uniqueness for a variety of reasons, but most immediately in its ability to sustain life. Earth is our only home, so it is so important that we take whatever measures we can to reduce our negative impact on it and work towards a cleaner, greener future!
I’m sure many of you are familiar with the James Webb Space Telescope: the successor to the Hubble Telescope and most powerful space telescope built to date. It was launched into space a little more than one year ago with the goal of observing the first galaxies and investigating our cosmic origin. In this short period of time new groundbreaking discoveries seem to appear every few weeks, but a particularly interesting observation was made about a week ago.
For some context, most galaxies are approximately 10 to 13.6 billion years old, and our own Milky Way is 13.61 billion years old. These ages are representative of the oldest parts of each galaxy, not all parts of the galaxy as a whole. Compared to the estimated age of the universe at 13.8 billion years, the oldest galaxies only started forming a few hundred million years after the Big Bang. New galaxies continue to form billions of years later with the youngest galaxy we have observed being close to 500 million years old (source). All of this is widely accepted by scientists; however, new images from the James Webb Telescope have thrown this into question.
An image (shown below) released by the telescope features a few fuzzy red dots which astronomers believe are six possible galaxies. These galaxies are not the oldest discovered, forming approximately 500 to 700 million years after the Big Bang. Their age is unsurprising, but their red color and immense size is. Based on preliminary calculations, these galaxies are estimated to be on par in mass with the Milky Way–almost 50 times more massive than ever expected, and yet are 13 billion years younger. Forming so many stars that quickly shouldn’t be possible based on the amount of non-dark matter available at that time (source). Combined with the red color which indicates very old stars, these potential galaxies’ appear much older than they should be. From our current understanding of the universe, these galaxies should not exist at all. Before we rewrite widely accepted theories, more research needs to be done on what else the galaxies could be, or what is causing their red color if not old stars. However, it raises lots of questions about our understanding of star formation and the behavior of the early universe.
Do you think we will have to rework our model of early galaxy formation, or is there another explanation? Read more about the discovery here. I also highly recommend looking through the JWST’s library of photos.
Source: James Webb Space Telescope at NASA, ESA, CSA, I. Labbe
Posted inGalaxies, Universe|Taggedastro2110, blog4|Comments Off on James Webb Space Telescope Discovers “Impossible” Galaxies
During class, we have discussed magnetospheres, tectonics, geological activity, and their relation to the cores of the “Big Five”: Earth, Venus, Mercury, the Moon, and Mars. Specifically the moon has very obvious cratering across its entire surface, and its craters remain intact for billions of years. This is due to it not having an atmosphere which contributes to erosion, and most significantly the Moon has a cold, dense core that does not allow for great geological or tectonic activity. When I think of moons in general, I tend to think of all of them having a generally rocking and cratered surface. However, this is not always the case, as is demonstrated by the Galilean Moons.
While Callisto and Ganymede resemble our Moon somewhat in appearance, with visible craters and dark areas–in fact Callisto is one of the most heavily cratered objects in our solar system, Io and Europa look much different.
Io varies greatly in appearance from most other moons due to its yellowish color, surface littered with massive volcanoes, and obvious lack of cratering. Although volcanoes are typically associated with tectonic activity as on Earth, this is likely not the case for Io. Io actually has an elliptical orbit because it is in a constant struggle with the gravitational force provided by Jupiter and the other Galilean Moons, Europa and Ganymede. This causes Io to bulge as it orbits and experience extreme tidal forces. The tides and tidal friction cause Io to generate large amounts of heat (source). This heat radiates outward and fuels the constant volcanic activity on the surface. In turn, this volcanic activity causes the surface to constantly renew itself, explaining its lack of cratering. Although Io likely has an iron core, it does not cause the geological activity on its surface, and might not have a magnetic field at all. More information about Io’s surface can be found here.
Europa, which is a little smaller than our moon, has a very unique appearance with lots of “scratches” and deep cracks running all along its surface, and there are only a few craters. The lack of widespread cratering implies its relative youth (40-90 million years old) and that recent geological activity has removed them (source). Scientists believe underneath the icy crust (about 10-15 miles thick) is an ocean that the surface rests on. The much hotter iron core in its center causes the ice layer to move as the cooler, denser ice sinks and the warmer ice rises to the top. The ice layer separating due to this motion likely causes the cracking on the surface, and ice plates converging causes tall ice ridges. Another indication of potential geological activity is evidence of water being vented into space from its surface. This is likely due to tidal friction as mentioned with Io. Europa also has a unique magnetosphere which creates noticeable disruptions in Jupiter’s magnetic field, and could possibly be explained by a salty ocean resting under its ice layer. All of these factors contribute to the hope that Europa could one day sustain human-life due to its similarities with Earth, and more evidence continues to be collected. More information about Europa can be found here.
Today, we’re taking a quick jaunt outside our solar system to visit the Pleiades. This grouping of stars–commonly referred to as Messier 45 (M45)–is one of my favorite observables and can be best viewed in January–but the cluster is easily visible from late fall through the winter. The cluster is currently moving through a cloud of interstellar dust and is located about 440 light-years outside of our solar system. Interacts between the light from the stars and the dust give the appearance of a wispy haze around some of the cluster’s hottest and most luminous stars–the brightest of which is about 1000 times more luminous than our sun. But from our vantage point on Earth, we can view (with the naked eye) about six or seven stars of the over 1000 stars found within this open star cluster by looking towards the constellation Taurus or by using Orion’s shield and Aldebran as pointer stars.
As one of the brightest star clusters in the night sky, numerous cultures have their own names and mythologies associated with m45. In Japan, for example, the cluster is known as Subaru. (Sound familiar?)
But the story I am most familiar with is one of at least two from Ancient Greece. For seven long years, the hunter Orion chased the seven daughters of Atlas throughout the known world. Just before the giant could seize the sisters, Zeus changed them into the brilliant stars that adorn the sky to this day. But for Orion, the hunt continues. His constellation pursues the seven sisters across the sky, and every night their eternal chase begins anew.
You may be familiar with Andromeda, our closest neighboring galaxy. You may have also heard that Andromeda and our Milky Way are moving towards each other. But what will happen to Earth and the rest of our solar system when these two galaxies collide? Will Earth even still be around by then?
The answer to the second question is likely yes, at least based on the projected lifetime of the Sun. The Sun should live for about 10 billion more years. However, in about 5 billion, it will turn into a red giant and expand into Earth, burning it up. Humans will not be around to see that, unless we relocate to a different planet. Earth will stop being able to sustain human life in about 1 billion years, due to the Sun increasing in brightness and drying up the oceans.
As for Andromeda, it is expected to collide with us in about 4 billion years. With this timing, the Sun will not be a red giant yet, and therefore all the planets will still be intact unless something else happens to them. While a collision of galaxies sounds very catastrophic, scientists agree that it is unlikely that our solar system would be harmed in any way, due to how spread out stars are in each galaxy. The odds of any two stars in either galaxy crashing into each other are extremely low. The black holes at the centers of each galaxy would merge, with Andromeda’s black hole of 100 million solar masses swallowing ours, which is only 4 million solar masses. After this merge, computer simulations from Hubble data predict that it will take about 2 billion years for the contents of each galaxy to completely merge and reshape into one elliptical galaxy. While this reshaping takes place, it is predicted that our solar system will be thrown much further from the center of the galaxy than we are right now.
Although this collision of galaxies would be unlikely to affect the lives of anyone living in either galaxy, astronomers could have a pretty good time with the event. As Andromeda and the Milky way get really close together, it may be fun for any intelligent lifeforms to observe another galaxy so close up, especially since from Earth, much of our view of our own galaxy is obstructed by dust. Would you want to live through an event like this?
A rendering from NASA of what Andromeda (left) and the Milky Way (right) may look like from Earth in about 3.75 billion years when they are closely approaching collision.
In studies of galaxies and star clusters, astronomers have found that many of these bodies appear to move in ways that don’t reflect the amount of visible matter in the system. For instance, some galaxies appear to orbit much faster than they should be based on the amount of stuff we can see within them. This fact, in the absence of any other explanation, has led astronomers to the conclusion that there are large amounts of matter in the universe that we can’t see. Hence the name dark matter. This hypothetical form of matter doesn’t interact with the electromagnetic field at all. This means that we can’t measure it or detect it in any of the conventional ways that we find other things in space. Despite the lack of direct evidence for its existence, dark matter is estimated to account for about 85% of mass in the universe[1].
This is obviously a massive amount of stuff, and it’s kind of hard to accept that such a high percentage of matter in the universe is invisible to all of our instruments. The first thought in my mind when I see that number is that we have to be missing something, and that there can’t possibly be that much in the universe that we can’t see. That’s the human response that I have, but I think it’s important to step back and look at it objectively. While we obviously haven’t found and perfected every technique of investigating the cosmos, we have done pretty well with our tools so far and they have been effective in investigating a large number of astronomical phenomena. All of our observational evidence points to the existence of a large amount of matter that is currently invisible to us, and we have to accept that that must be true unless we want to discount all our proven laws of physics and methods of observation. So despite that initial reaction of disbelief, I think it probable that there is a very large percentage of mass in the universe that we can’t see, but I do believe that we may be able to develop some instrument or method that allows us to more directly detect this matter. Either way, it is a very cool concept, and it will be exciting to see what new information comes out about dark matter as we make new astronomical discoveries.
Nuclear fusion is the process that powers our sun, as well as all the other stars in the Universe. At the most basic level, nuclear fusion is the combination of two light atomic nuclei to form a heavier one along with a release of energy. This reaction is governed by Einstein’s E=mc^2 equation, where some of the mass from the initial part of the reaction is converted to energy. Since the total mass of the resulting particle is less than the total mass of the initial particles, the energy released from the reaction is equal to the difference between the initial and final masses, multiplied by the speed of light squared[1]. For reference, if one kilogram of matter was fully converted to energy, it would release about 8.99 x 10^16 joules of energy. This is enough energy to power the entire city of New York for over a month[2]. As you can see, fusion reactions can produce enormous amounts of energy at a time, and the sun experiences about 9.3 x 10^37 such reactions per second.
Now, it is important to note that a kilogram of mass is never instantaneously converted to energy as mentioned above, at least not in any process that we know of today. The masses being converted to energy per reaction in the sun are around 4.8 x 10^-29 kilograms[3]. A reaction with this amount of mass conversion releases 4.3 x 10^-12 joules of energy. Taken alone this is quite a small amount of energy, but if you multiply it by the number of reactions per second in the sun it becomes very large. Overall, fusion reactions produce about four times more energy than the fission reactions currently achieved in nuclear reactors on Earth, and would therefore be the preferable form of nuclear energy once the technology becomes available.
