A Deep Journey To Our Neighboring Galaxy Andromeda.

A journey through the Andromeda Galaxy Andromeda is a large spiral galaxy, a big monster of about 1 trillion solar masses. It lies about 2.5 million light-years away from the Earth, but this distance will shorten with time because Andromeda is moving towards us at the crazy speed of 68 miles or 110 kilometers per second. In some billion years, it will collide with our galaxy. This will be the collision of the two largest galaxies in our local group. Eventually, the two galaxies will merge into one. Scientists often refer to the new object as Milkdromeda, but I'm sure there could be better names for it. What would you call it? Let us know in the comments! Andromeda is a really interesting galaxy, and it has always played a crucial role in helping us understand our place in the universe. This video will show you everything that you need to know. Oh, I almost forgot. Our cute neighbor is an evil cannibal galaxy. We'll talk about this as well. Don't miss out! How to spot Andromeda The Andromeda Galaxy is the second most famous galaxy in astronomy after the Milky Way, at least for us humans. According to the standard astronomical classifications, we can identify four types of galaxies, spiral, barred spiral, elliptical, and irregular. Andromeda is a barred spiral galaxy, just like the Milky Way. A barred spiral galaxy is a spiral galaxy with a central bar-shaped structure composed of stars. Bars are found in about two-thirds of all spiral galaxies, and generally affect both the motions of stars and interstellar gas within spiral galaxies and can affect spiral arms as well. The Andromeda Galaxy is located 2.48 million light-years from Earth, as we will see later in the video. But I'm sure among you guys there's someone who has just acquired a telescope and wants to find objects in the night sky. Well, I have good news for you. You can spot Andromeda on a clear night by pointing your telescope towards the Andromeda constellation. The first path to Andromeda starts from the constellation Cassiopeia. Cassiopeia is easy to find because its stars form a distinctive W-shape. You can use it as a reference constellation to find the Andromeda Galaxy. If you have binoculars, and most importantly if the sky is dark, which means you're in a place where light pollution is small, you will be able to see a pale puff of smoke, slightly elongated. That's Andromeda. And if you're lucky enough, under optimal circumstances, you can also spot Andromeda with the naked eye. Well, ladies and gentlemen, for the Northern Hemisphere, this is a real miracle. Andromeda is the only extragalactic object we can see with our naked eye. It is the furthest object our eyes can catch. Isn't it amazing? The light from billions of stars traveled for a distance corresponding to 2.48 million light-years, meeting all sorts of atoms and molecules, and finally fell in the pupil of your eye. Andromeda has a diameter of about 46.56 kiloparsecs, or 152,000 light-years, making it larger than the Milky Way in terms of extension. If it wasn't too faint and we could see the full Andromeda Galaxy, spiral arms included, with the naked eye, this is how it would look like. Don't you think it's beautiful? The mass of the Andromeda Galaxy is huge, with about 1 trillion solar masses, of the same order of magnitude as that of the Milky Way, even if most estimates are subjected to errors. For example, before 2018, Andromeda was thought to be two or three times the size of the Milky Way, but more recent measurements showed that our neighbor is just about the same size as our own galaxy. History of the Observations Anyway, where did we get all this knowledge about our neighboring galaxy? Apparently, everything started in the year 905, when a Persian astronomer described the presence of a small cloud in the Andromeda constellation. Star charts of that period have it labeled as the Little Cloud, but it took humanity more than 700 years to get the first description of the object, based on telescopic observations by Simon Marius. Then the famous astronomer Charles Messier labeled it as M31 in his famous catalog. Nowadays, this galaxy is known by a bunch of different equivalent names. You can call it Andromeda, or M31, or NGC 224. They all refer to the same beautiful galaxy. Observations carried out by Herschel and Huggins turned out to be really precious, but by the end of 1884, Andromeda was still considered only a puffy cloud or nebula. One important thing to be noted here is that back then, no one knew about the presence of other galaxies beyond the Milky Way. Some people argued that these nebulae were island universes, objects like our Milky Way galaxy, but external to it. Others disagreed and thought that these spiral objects were clouds of gas within the Milky Way. The argument went on until the 1920s, when the American astronomer Edwin Hubble finally measured the distance of Andromeda. Let's see how he came up with this conclusion and forever revolutionized the understanding of our place in the universe. Andromeda and Hubble Edwin Hubble is a name synonymous with the study of extragalactic astronomy. In 1923, he made a groundbreaking discovery when he discovered that the Andromeda nebula was actually a distant galaxy and not just a puffy cloud. This observation marked the end of a long-standing debate about the nature of spiral nebulae and changed the way astronomers view our universe. The astrophysics genius realized that one of the objects he was observing within the fuzzy nebula was in fact a Cepheid variable star. These stars' brightnesses change periodically over time. What's so important about Cepheids? Well, allow me to explain. In the early 1900s, Henrietta Leavitt, an American astronomer, found what is known as the period-luminosity relationship, a link between the luminosity of a Cepheid and its period. Basically, by studying the variation in light coming from a Cepheid over time, we can get its intrinsic luminosity. This is really important because if we know the intrinsic luminosity of an object, we can get the distance at which it must be placed in order to get the observed brightness. It's a simple concept, really. Think about it this way. You have two equal cars, equipped with the same headlights. If you place one of them further than the other and you switch them on, you will see one's headlights brighter than the other. The further you place the second car, the dimmer it will appear to you, even though the cars have the exact same headlights. Therefore, the observed brightness depends on the distance between you and the cars. The same thing happens with stars and objects in the universe. The further the object, the dimmer it will appear in general. But if you know the intrinsic value of the brightness of the headlights, or the star, you can then estimate the distance between you and the object of interest. By utilizing the period luminosity, PL relation, then Hubble was able to measure the period of a Cepheid in the Andromeda Nebula and use it to determine its luminosity and distance from the Earth. Since the Cepheid star belonged to Andromeda, its distance was equivalent to the distance of the galaxy. The number he calculated was the number that changed our way of seeing the universe forever, about 1 million light-years. A figure that placed what was known as the Andromeda Nebula, very much more distant than hitherto assumed, a distance that necessarily had to be located outside our Milky Way. In 1929, Hubble published his findings, which included a graph plotting the velocity of galaxies against their distance. He found that galaxies were moving away from us, but at a rate that was proportional to how far away they were. This became known as Hubble's Law. At the time of Hubble's discovery, the estimated value of the slope of the graph was much higher with respect to today's estimates, due to an incomplete understanding of Cepheid variables. However, recent advances in astronomy have enabled researchers to narrow down the value of Hubble's constant to about 70 km per second per cubic megaparsec. This means that galaxies recede an extra 70 km per second for every megaparsec of distance from us. And when Hubble's discoveries revolutionized the way astronomers think about our universe, and the impact of his work continues to be felt today. The Hubble Space Telescope, the most famous space telescope ever built, and perhaps the best so far, was named after him. And guess what? This image, captured with the NASA ESA Hubble Space Telescope, is the largest and sharpest image ever taken of the Andromeda Galaxy. This is actually a cropped version of the full image, and has 1.5 billion pixels. There's no way you could display the whole image, you would need more than 600 HD television screens. It is the biggest Hubble image ever released, and shows over 100 million stars and thousands of star clusters embedded in a section of the galaxy's pancake-shaped disk, stretching across over 40,000 light-years. Thanks, Hubble! The local group, Andromeda eating other galaxies, cannibalism So we have seen how Andromeda was crucial for us here on Earth. Without exaggerating, we could say the measurement of the distance of Andromeda allowed a shift of paradigm. Before, we thought the universe coincided with our galaxy. After it, we knew our galaxy was not alone anymore. Nowadays, billions of galaxies are thought to populate the universe and they have different shapes and sizes. As we already mentioned, some of them are elliptical galaxies, others are spiral galaxies, and some of them are irregular with their crazy shapes. Most of these galaxies are far away from our home galaxy, but our local group of galaxies is different. It consists of our neighboring galaxies within the vast universe. It is composed of nearby galaxies in the vast universe located within roughly 5 million light-years of space around us, with a diameter of about 10 million light-years. Andromeda and the Milky Way are not the only members of the local group. There is also the Triangulum galaxy, as well as 50 dwarf galaxies. This small cluster of galaxies can be considered relatively close, as it is only millions of light-years away instead of billions. From a dark sight, some of the galaxies in the local group are even visible to the unaided eye. It is believed that the local group does not have a true center. Rather, the gravity center lies somewhere between the Milky Way and the Andromeda galaxy, the two most massive galaxies of the group. This is really beautiful. We could say we are part of a family of galaxies, formed who knows how billions of years ago. But there is something more. Are you ready to get your mind blown away? Astronomers have discovered that our local group is on the outskirts of a giant supercluster of galaxies known as the Virgo supercluster. The incredible thing is that while our local group is considered a large structure, it is relatively small in comparison to this supercluster. Nonetheless, it is still a spectacular feat that we are able to observe and learn more about our neighboring galaxies from the comfort of our own home galaxy. Unfortunately, some of the members of the local group have been probably less lucky than others and have been eaten and swallowed. The Andromeda galaxy is in fact an example of an impressive cosmic cannibal. Galactic cannibalism is a common phenomenon that occurs in the universe, which refers to the process in which a large galaxy, through tidal gravitational interactions with a companion, merges with that companion, which results in a larger galaxy. Basically, this is how galaxies get fat. In a study published in Nature, an international team of astronomers has reconstructed the history of this evil spiral galaxy and has concluded that Andromeda has swallowed up smaller galaxies at least twice over its 10-billion-year lifespan. Using 77 globular clusters orbiting Andromeda, the team was able to measure the velocities of these clusters and reached the conclusion that Andromeda has undergone two distinct feeding frenzies, one of which was more recent and another ancient. This has resulted in the galaxy being warped and twisted with a much more violent past than the Milky Way. The research offers a greater insight into how galaxies like ours form and will help us better understand their evolution throughout the universe. Andromeda offers a great example of how galaxies can feed off one another, as well as a reminder of the power of astronomical research. Our next-door neighbor is a monster, and thanks to science, we now know just how. In general, the cannibalism phenomenon can happen whenever two galaxies start an interaction. These are some of the amazing images of interactive galaxies we've found. Dark matter Among other things, Andromeda could help us shed light on one of the unanswered questions in astrophysics. Does dark matter really exist? In 2017, NASA's Fermi Gamma-ray Space Telescope has found a signal at the center of the galaxy. This could indicate the presence of the elusive dark matter. Gamma rays are really powerful rays of light produced by the universe's most energetic phenomenon. What scientists expect from dark matter in galaxies is for it to accumulate in the innermost regions. Well, guess what? Surprisingly, Fermi's data shows the gamma rays in Andromeda are confined right in the galaxy's center. Scientists think the gamma ray excess could actually be produced by a variety of processes. For example, a possible source for this emission could be a rich concentration of pulsars in N31's center. These peculiar objects are among the densest objects in the universe. They are so dense that one teaspoon of a pulsar would weigh a billion tons on Earth. Some pulsars emit light in the gamma regime, but it is really hard to spot individual pulsars in a galaxy like Andromeda 2.48 million light-years away. Of course, more observations will be needed to determine the source of the gamma ray signals coming from Andromeda's center, but this discovery surely provides an exciting starting point to learn more about galaxies and perhaps the mysterious nature of dark matter. Collision with the Milky Way We talked a lot about Andromeda and its features going through past observations and present knowledge. But what does the future hold for this galaxy? Let's look 4.5 billion years into it. Imagine some of your descendants are standing with their teacher, looking up at the night sky. Thousands of stars are shining bright, and a bunch of them are being born, their teacher tells them because of an immense cosmic event. The Milky Way has collided with Andromeda. Although the relative velocity of the two galaxies is something like a million miles per hour, the whole process took millions of years to complete. The teacher tells them that when everything settles down, the two galaxies have merged into a bigger one, Milkdromeda. You can imagine both the stupor and the fear of the kids, but the good teacher reassures them that there is a very tiny chance of stars from the Andromeda galaxy hitting the Sun or the Earth. The stars in a galaxy are spaced very far apart. To make a comparison, they are just like grains of sand separated by the length of a football field. This is our destiny. A slow collision with our galactic neighbor. This is how the universe changes over time, in an ever-changing cosmic dance between galaxies. In any case, the collision of the two galaxies is estimated to occur in 500 million to 1.5 billion years, and by this time the Sun's luminosity will have already increased by 35-40%, causing a runaway greenhouse effect on Earth and making it too hot for liquid water to exist, resulting at the end of all terrestrial life. If we want to watch the two galaxies merging, it would probably have to be from another planet. What will happen to Earth when the Milky Way and Andromeda galaxies merge? Galactic Habitable Zone If you are a faithful follower of Insane Curiosity, surely more than once you have heard about the famous Habitable Zone, a region around a star where the temperatures are ideal for a planet to have water in a liquid state, that is, an area that is neither very hot nor very cold. But did you know that galaxies also have a Habitable Zone? Yes, this is the Galactic Habitable Zone, defined as that region of a galaxy in which the necessary conditions exist for life to arise and to prosper for billions of years. Currently, it is considered that the defining parameters of a Galactic Habitable Zone are two. 1. Abundance of heavy elements and 2. Cataclysmic astrophysical events. The first refers to the chemical elements necessary for forming organic chemistry, mainly carbon, oxygen, and nitrogen. This parameter is known in astrophysics with the name of metallicity. The medium and massive stars produce these heavy elements, releasing them into the interstellar medium at the end of their existence, either as planetary nebulae or as supernovae. The regions that have had more generations of stars of these types are those with the highest metallicity and, therefore, where the emergence of the chemistry necessary for the appearance of life is more likely. Thanks to these stars, the availability of chemical elements for life reaches its maximum near the galactic nuclei and decreases as we approach the edges. The second factor is the frequency with which highly energetic phenomena occur with the capacity to emit large amounts of radiation or particles since these emissions could destroy organic molecules and life. Cataclysmic astrophysical processes are supernova explosions, gamma-ray bursts, high star formation rates followed by mass supernova explosions, and jets forming in the accretion black hole disks. These events are also more frequent in the galactic nuclei and less frequent at the edge, making the chances of sustaining life greater outward than towards the galactic center. The conjunction of these two factors in spiral galaxies results in that, on the one hand, the edges are more difficult for life to emerge, even though they are safe areas, due to the lack of heavy elements. And on the other, the nuclei are not conducive either, since, although they have a high concentration of heavy elements, they are the areas with the highest radiation levels and the most frequent cataclysmic events. So, in spiral galaxies, there is an intermediate ring between the nucleus and the edges, where the possibility of the emergence of life and the possibility that it thrives for billions of years is increased to let evolution do its job. A region where the rate of cataclysmic events is not as low as the edges but much lower than at the core and where the amount of heavy elements is not as high as at the core but is more significant than at the edges. This ring is the galactic habitable zone, that is to say, the galactic habitability zone. In this context, it is not uncommon for the location of the Sun in the Milky Way to be precisely in this region. Even though the galactic habitable zone is considered conducive to life, no concrete evidence of life has yet been found anywhere else in the Milky Way. However, several stars within the galactic habitable zone have been identified with planets within their star's habitable zone, raising the possibility that life exists elsewhere in the galaxy. Since we only know of one example of life, there is not much certainty about the minimum degree of metallicity necessary for the complex chemistry that leads to life to arise. Furthermore, for each galaxy, more detailed studies are required to take into account the differences in metallicity between the spiral arms and the spaces between them. But for now, at least in our galaxy, there is this galactic habitable zone and we are lucky to be there. Where will the new habitable zone be? What will happen when the Milky Way and Andromeda merge? What will happen is that this habitable zone will change places and so will the Sun. The merger of both galaxies will give rise to a new galaxy called Miltromeda, which will be larger and whose habitable zone will travel more towards the edges because the center will have a higher concentration of stars. Both galaxies will exchange stars during the merger process, so the Sun will inevitably leave the galactic habitable zone and migrate to other regions where conditions will differ. If the Sun moves outside the galactic habitable zone, this would have significant consequences for life on Earth. For example, if the Sun were too close to the galactic nucleus, the intense radiation and stellar activity in that region would make it very difficult for life to develop and survive. In addition, the presence of large amounts of dust and gas in that region would also make it difficult for planets to form and sustain. In addition, in the new galaxy resulting from the merger of the Milky Way and Andromeda, there will be a greater concentration of stars near the nucleus, which would cause the forces of gravitational attraction of nearby stars to affect the Sun. If that were not enough, the supermassive black holes of both galaxies will merge and create one even larger, whose gravitational pull will affect all stars several thousand light-years away. So, if the Sun gets too close to the galactic nucleus, it is unlikely that life will thrive on any of the eight planets in the solar system. On the other hand, if the Sun were too far from the galactic center, things would not be so bad on Earth. In this scenario, the number of heavy elements necessary for life would be much lower, making it difficult to form and maintain planets with the right conditions for life. Still, as long as we manage to live in harmony with the Earth's resources, we will survive. Also, the stellar density at the galaxy's edge is much lower, which means that the frequency of catastrophic events such as supernovae and asteroid collisions would also be lower. If the Sun were too close to the galactic nucleus, cosmic radiation and powerful streams of interstellar gas and dust would significantly affect the chemistry of Earth's atmosphere and the stability of the climate. Also, the intense stellar activity in that region would mean that the chances of Earth being hit by celestial objects like asteroids and comets would be much higher. There would also be a greater chance that the Earth would be exposed to dangerous gamma ray and X-ray emissions, which would severely affect all living things. On the other hand, if the Sun were at the galaxy's edge, nearby stars would be much less common, meaning Earth would be exposed to less cosmic radiation and less likely to be hit by dangerous celestial objects. However, the lower stellar density would also mean the Sun would be left alone. The closest star to the Solar System would no longer be Proxima Centauri, but another star much farther away, perhaps hundreds of light-years away. Effects on Earth As you can see, it is impossible to predict precisely where the Sun will move when both galaxies merge into one. It is tough to calculate the gravitational effects that billions of stars will exert on the Sun for thousands of millions of years. We must also remember that by then the Sun will have already begun to die, and all the planets in the Solar System will have ceased to be habitable. But if humanity somehow manages to survive all of this, we'll be fine if the Sun doesn't migrate a distance that puts it closer to the galactic core. Since if the fusion between the Milky Way and Andromeda takes us to the galaxy's edges instead of the center, it will be the best news. Although there are not enough materials in this region for other planets to form, at least life on Earth will be safe and we can worry about getting materials later. But if, on the contrary, the Sun moves towards the center of the galaxy, there is no need to be alarmed either. Remember that this event will occur within 4.5 billion years, and will take more than 5 billion years to finish, so we will have enough time to leave our Solar System and find another, safer place to shelter. But let's use the power of imagination and imagine what the merger of both galaxies would look like from Earth. Currently, the Andromeda Galaxy is tough to see in the sky, since it looks like a nebula instead of a galaxy. Still, in many years that will change and it will look bigger and bigger until one day, in billions of years, it is visible even during the day. If the Solar System migrates much closer to the galactic nucleus, the night sky will look very different than it does today. First, the number of stars visible would increase dramatically. Currently, we can see about 2500 stars with the naked eye from Earth, but if we were closer to the galaxy's center, we would see tens of thousands of stars. Also, the Milky Way's shape would appear much brighter and more defined in the night sky. The whitish strip that we currently see in the sky would be much brighter and broader. Also, we would be able to distinguish the shape of the galaxy's spiral arms more clearly. Also, we could see many more nebulae and star clusters. It would be an impressive spectacle. Every night we could see gigantic and colorful astronomical objects, something that nowadays we can only see in the movies. However, being close to the galactic core would also have its drawbacks. First, the cosmic radiation that would reach Earth would be much higher. This could harm living things on Earth, as cosmic radiation can damage DNA and increase cancer risk. Furthermore, the presence of a supermassive black hole at the center of the galaxy would be much more evident and potentially dangerous. As the Milky Way and the Andromeda galaxy come closer and eventually collide, the black hole at the galaxy's center may become active and emit jets of high-energy matter and radiation. These jets could threaten Earth and its biosphere if the system weren't close enough, destroying the atmosphere and also all living beings. Conversely, the night sky would appear much darker if the solar system migrates to an area much further from the galactic core. The Milky Way would be much less prominent, since much of its brightness comes from the concentration of stars and dust at the galactic center. Furthermore, the distribution of stars in the sky would also change. Instead of having many bright, close stars, you would see few individual, distant stars in all directions. Also, many of these stars would be difficult to see with the naked eye, due to their great distance and low luminosity. In general, the night sky would be less spectacular than what we are used to seeing today. But the good side is that in this scenario, any life form that is still on Earth will survive without significant setbacks. Will there be star clashes? In the nuclei of both galaxies, there will surely be several collisions between the largest and most massive stars, especially near the black holes. But in the center and edges, these events will not occur or will be extremely rare, since the distances separating the stars are enormous. And even if the galaxies merge, most of the stars will not touch. A new big blue gas cloud seen near Andromeda, the galaxy we thought we knew well enough. How come we never discovered it before? Hundreds of telescopes, both on the ground and in space, have been used to explore the sky. Yet even with this extensive study, we still have much more to discover. As evidenced by the recent finding of a gas cloud near the Andromeda galaxy, the sky still has many secrets to unearth. For decades, this cloud went undiscovered, and its origins remain unknown. There is still much to uncover. Thanks to the affordable yet outstanding quality of digital detectors, astronomical photography is now simpler than ever. This has brought about a new trend among astronomy enthusiasts to concentrate on a particular part of the sky and take exposures that are comparable to long-term exposures, with the goal of discovering any faint fuzzies that reside there. In this picture, we see Andromeda, and above it we observe a blue ghostly figure. What is that? It's a very unusual and intriguing discovery from the nearby Andromeda galaxy. This discovery was made by independent astronomers Marcel Dreschler, Xavier Strattner, and Jan Sainty back in 2022. They used simple techniques such as applying different filters and observing the same spot for a long time, a concept known as long exposure, to find something that had previously been missed by other surveys. They decided to focus their efforts on the Andromeda galaxy, a spiral galaxy similar to the Milky Way, located 2.5 million light-years away, that has been studied by astronomers for over 100 years. With its most notable features already mapped, they believed that any leftover discoveries would be smaller, individual elements such as nebulae in the galaxy itself. While doing this, they accidentally came across an object outside the galaxy. At first, it didn't seem to make sense because it was too big to be associated with Andromeda. It appeared to be an unusual arc stretching further away from Andromeda, and was only revealed after a 160-hour-long exposure using the 4-meter-long Canada-France-Hawaii telescope with a 400-megapixel camera. This object was confirmed by independent observations, which revealed it to be an oxygen cloud or arc, or now known as M31 Oxygen Emission Arc, or Strattner-Drexler 70 Object 1. Sainty shared his findings with Drexler and Strattner for them to examine and analyze. As they carefully looked at the pictures, they were astounded to discover a large and elongated structure, almost as large as the Andromeda galaxy right adjacent to it. When Sainty used a filter to capture images that only let through the blue-green light from doubly ionized oxygen atoms, atoms that have lost two of their outer electrons, a common phenomenon in giant gas clouds, the nebula was made visible. The use of this filter was largely due to his curiosity, as it was the first time a large-scale map of the sky around Andromeda has ever been created. During the same observing session, Sainty took deep images using a different filter that was sensitive to light from hydrogen atoms. He noticed many gas clouds in the vicinity of Andromeda, most likely nebulae from our Milky Way in the same region of the sky as Andromeda, but there was nothing that matched the size and shape of the rare oxygen-rich nebula. The team questioned if the cloud in Sainty's images was some sort of abnormality, such as refracted light from his telescope. To verify this, the researchers requested that renowned amateur astronomer Bray Falls observe the cloud with his own telescope. Falls likewise observed the nebula, confirming it was real. Observations from five telescopes located in France, California, and New Mexico ultimately persuaded the team that the object was real, thus leading to its nickname, Strottner-Dreschler-Sainty Object 1, SDSO 1. But I'm sure you're all still asking yourselves, what is it though? After seeking expert advice, the findings of the collaboration between Robert Fessen, Michael Schull, and Stefan Kimswinger, and amateur astronomers, was published in the American Astronomical Society's journal Research Notes of the AAAS. Although tantalizing, the origin of this nebula remains very elusive. This photo of Andromeda captured in visible light with red, green, and blue filters is stunning, yet there is no evidence of the large cloud known as the Strottner-Dreschler-Sainty Object 1, SDSO 1. Investigation of various hypotheses has been concluded by astronomers, yet the gas cloud remains unexplained. Its close proximity to Andromeda in the night sky suggests a connection, and its curved shape suggests that it is bulging from the galaxy. Although these features do not definitively prove a bond between the cloud and the galaxy, they certainly indicate one. If SDSO 1 is indeed part of, yet outside of, Andromeda, this would mean the cloud spans a length of tens of thousands of light-years, and would become one of the largest coherent structures that Andromeda has. If the cloud is located in Andromeda's colossal halo, a broader circular swath of stars encircling the galaxy, it might be composed of the gas thrown away by the stars it contains. However, since the stars are mainly composed of hydrogen, then there should be plenty of hydrogen visible, but as Sainty proved with his hydrogen-detecting filter, there was not enough to be seen. SDSO 1 lies between the Milky Way and Andromeda, which may provide insight into the interaction between them. As they pass each other in space, their individual halos may be bumping into each other, compressing any diffuse gas into a curved, bow wave, similar to that from a boat moving through the water. If this were the case, the cloud should be situated roughly halfway between the two galaxies rather than just near Andromeda, and this still does not explain the absence of hydrogen. It is possible that the cloud is actually much closer to us, being a nebula in the Milky Way and merely appears to be in the Andromeda galaxy. These planetary nebulae are made up of gas discharged from dying stars that are mostly composed of hydrogen and oxygen. This makes them appear illuminated as a result of light emitted by these two elements. However, the absence of hydrogen in SDSO 1 is still strange. It is conceivable that SDSO 1 might be the survivor of a Milky Way star which detonated like a supernova. However, it ought to be incandescent in ultraviolet light and radio waves. The researchers, nevertheless, observed no radiance from the nebula at any other wavelengths, such as X-rays, visible in infrared light when looking through archived photographs of Andromeda. No existing explanation covers all of the available facts, and it's certainly puzzling. But that's also what scientists find so exciting. We became researchers to work on puzzles, and this is one that we're eager to solve. It's amazing that SDSO 1, a celestial body as large as three full moons, was only recently discovered considering the narrow field of view of large telescopes. Astronomers aren't entirely surprised, though, because the bigger instruments couldn't spot the object. They couldn't see the big picture due to focusing in too closely. SDSO 1 is very dim, making it difficult even for professional observatories to detect it. The discovery and confirmation images using the doubly ionized oxygen filter took 160 hours to capture. The 3.8-meter Canada-France-Hawaii telescope, which has an impressive 378-megapixel camera and oxygen filter, looked directly at the area in the sky where SDSO 1 lies, and still couldn't detect it. This is because the telescope is not designed to observe objects that are large and faint. Using spectroscopy to break up the cloud's wavelengths, the velocity of the gas in SDSO 1 can be identified by studying the blue shift or red shift of its color. If the cloud is moving at a similar speed to Andromeda, then it's probably associated with that galaxy, while a slower speed could mean it's part of ours. Research is ongoing, so the origin and behavior of this cloud remains mysterious for now. SDSO 1 may be puzzling, yet it is also a sign of optimism. It proves that there are still multiple fascinating objects in the cosmos yet to be discovered. All we have to do is use the correct approaches to reveal them. In the research paper they published in January of 2023, they explained that sky surveys that use optical emission lines can be very helpful in recognizing different types of emission nebulae, like H2 regions, planetary nebulae, supernova remnants, and wind-created cavities and outflows from stars. Most of these surveys focused on detecting H-alpha, the brightest hydrogen line emission along the galactic plane. Now that cost-effective high-sensitivity CMOS detectors and narrow passband filters with high transmission have become accessible, non-professionals can be seen making a larger contribution in recognizing emission-line nebulae, not only around the galactic plane but also in other places. They were able to conclude that the curved, filamentary structures seen in the emission arc could be a high-latitude galactic supernova remnant, a planetary nebula near the Milky Way, or related to the giant stellar stream in M31's halo. Further spectroscopic observations are being done to establish an association with M31. Nobody knows what this object is, how far away it is, what produced it, if it is even in the Andromeda galaxy, or how big it is. One potential explanation is that it could be related to the future collision of the Milky Way and Andromeda galaxies in the next few billion years. Some of the gas from the halo of Andromeda and the Milky Way has already started to interact, creating the arc-like shape. However, this object is in the wrong location for that theory to be true. Another explanation is that it is much closer to us and much smaller than expected, making it part of the Milky Way instead. At this point, there is no single explanation for what this cloud is. It is faint and difficult to see and contains no hydrogen, unlike typical planetary nebulae or stellar streams. Scientists are now working to get more data, such as the Doppler shift, in order to determine where the cloud is located and what it is. Hopefully, within the next few months, we will have answers about this object. It is a huge mystery and one of the biggest discoveries for independent astronomers in the last few years.