Galaxy and it’s Design – by Nazifa Noor

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There is no doubt in the fact that design is a fundamental part of our life. A life without design is no life at all. Design provides structure that can make or break. In many ways, design is synonymous to the word “plan”. Thus, it is absolutely undeniable that the universe is known to be the most carefully and efficiently designed entity ever. It is where life happens. It is where dreams are made, hopes are had.

If I were to elaborate on the entire design of the universe, I am afraid it would take too much of your time and probably leave a lot of questions unanswered. Mainly because not every single part of our world’s design is familiar with the scientists either. One question arises after another at every single stage of a discovery. Even then, in the past few years, they were able to make out some idea about what we all have been born into and most importantly, how it all functions.

Curiosity is what fuels us humans and curiosity will one day be able to perhaps answer all of our questions about how it all came to be.

The universe is comprised of everything we know to exist and don’t know to exist yet. It homes stars, planets, galaxies followed by other forms of matter and energy. Galaxies are like mini universes, if you will. It holds trillions of stars together, orbiting around a common center of gravity. Now that the formal definitions are over, let us delve deeper into the actual design of a galaxy.

So far, galaxies are classified into three basic shapes, namely: spiral, elliptical and irregular. They are quite different from one another but are beautiful in their own way.
Spiral Galaxies are known to have three visible parts. The first layer consists of a thin disk which is made up of stars, gas and dust. The second layer contains the central hump of older stars; while the third and final layer has a spherical halo that comprises of the oldest stars and other massive star clusters.

Our planet Earth resides in a barred spiral galaxy called “The Milky Way” and it contains over a 100 billion stars. Elaborating on the layers, we’ll find that the first layer, that is the thin disk, would consist of stars, gas and dust that are about 100,000 light-years across and 2,000 light-years thick – for a more visual idea imagine a few days old, dry flatbread. This thin disk appears to be far more compressed or leveled than that. As for the second layer, the central hump of stars is stretched into the shape of a bar.
Fun fact, the Romans named our galaxy “via lactea” which means “the road of milk”. This is because it looks like a milky patch of sky above our Earth at night. However, they weren’t the ones to name our galaxy. They got the name from the Greeks who called it “galaxias kyklos” which means “milky circle”.

Moving on with the elliptical galaxy, unlike our spiral abode they have a smooth rounded shape. This is due to the orbits of their stars being set in all directions. They don’t have as much gas, dust or young stars. Despite so, the spiral galaxy and the elliptical galaxy have one fact in common – they are both surrounded by orbicular star clusters and dark matter.

Irregular galaxies, on the other end, are chaotic in terms of appearance and are often small. Recent disturbances such as gravitational clashes with outer galaxies or bursts of internal star formations might be the reason for their shape.
Apart from these three, there are some galaxies called “active galaxies” (quite similar to irregular galaxies). They tend to give out huge amounts of energy in the form of radiation. Their unusual structures evoked astronomical attention and are thus now a big part of their research.

I suppose it could be felt that we are quite lucky to be in the type of galaxy we currently belong to, as the other two seem to be quite chaotic and uninhabitable.
Structure determines whether life can thrive or not. Although we don’t fully have enough knowledge about how galaxies came to be, we still know some factors regarding their past and evolution. 14 billion years ago, after the big bang, the amalgamation of gas and dust clouds that had collapsed created the galaxies of today. Several interactions and collisions with external galaxies later, evolution occurred.

There is a law placed to understand how this evolution occurs. It is known as the Hubble Law. The Hubble Law basically states that the universe is constantly expanding. It is believed that initially, the universe was filled with hydrogen and helium. It is also believed that some parts of it were denser than others. Now, these assumptions led astronomers to think that the denser areas took more time to expand.

First, small protogalactic clouds are formed. Protogalactic clouds are gaseous clouds that are beginning to form into new galaxies. It is the hub for budding galaxies. Gravity then leads the gas and dust to form a star. Here, there are two entities at play; the protogalactic clouds and gravity. These two are at charge of working together to start the formation of a galaxy. As the clouds fall apart they form rotating disks. These then attract even more gas and dust to form galactic disks. Inside this newly formed disk, more stars are born. Outside this creation there will be orbicular clusters, halo comprised of gas, dust and dark matter.

Apart from this there are two factors that determine whether the galaxy will be a spiral one or an elliptical one. Firstly, protogalactic clouds that have more angular momentum would spin faster and thus form spiral galaxies. Angular momentum is the product of inertia and angular velocity. Inertia is the tendency of an object to remain unchanged after facing movement, whereas the angular velocity is the rate of change of angular position of a rotating body. On the other end, clouds that spin slower would form elliptical galaxies. This is due to a lack of angular momentum. Secondly, how fast or slow the clouds cool down will also determine the type of galaxy they’ll turn out to be. High density clouds would cool faster leading to the prevention of the making of a galactic disk, hence forming an elliptical galaxy. Low density clouds are the opposite. They would cool faster and get time to form a disk, leading to the formation of a spiral galaxy.

When compared to stars, galaxies are designed to have larger diameters and are generally situated more close to one another. They can collide with, as well as pass through each other. This does not seem possible for stars to do. Usually collisions form irregular galaxies in the end but it is just one of the ways these galaxies reach evolution. Collision leads to new star formations, supernovae and stellar collapses that form black holes.

Galaxies are known to exist in clusters. The galaxies in such clusters share the same gravitational force and thus influence each other, much like how twins behave. There are two categories here. One is the rich cluster, which homes more than 1000 galaxies. Second is the poor cluster, which contains less than 1000 galaxies. The Milky Way and the Andromeda galaxy are a major part of a poor cluster containing just about 50 galaxies.

Despite living in clusters, these galaxies are distributed quite meticulously even though it may not seem like so when they are looked at once together. They might come off as “jumbled up together”, but in reality there are walls that separate them and they have intervals called voids between them too.

This space or void between galaxies or clusters of galaxies is not completely empty though. They do have some gas present as well as some intergalactic medium which isn’t a lot in amount. Not much is known about this medium but it has been speculated that knowledge about this may help to find out clear information regarding the origin of the universe, how galaxies are truly formed and how they change.
With the Hubble Law and the ever-changing nature of the galaxies in mind, we use the Hubble Space Telescope to observe galaxies and stars. The Hubble Space Telescope was shot into orbit on April 1990 along with the Discovery space shuttle. Since then, the telescope has helped redefine our views on space. We were able to find the age of our universe, discover black holes and find dying stars along with other things. Using this device we got to see and research more about our world and it has led us to find information to add about previously made assumptions in detail and with proof.

Now, how does this telescope work?

The Hubble Space Telescope (HST) has an eye (camera) that sees with the help of four CCD chips that are arranged in the shape of the letter “L” to catch light. CCD stands for charged coupled device. They are sensors used in digital cameras and video cameras to record still and moving images. The CCD chips include three low-resolution wide field chip and one high resolution planetary camera CCD chip. All four of the chips are used to spot the target and the target image is captured on any CCD chip desired. This eye can see visible light as well as ultraviolet light and take images through several filters to make natural looking pictures. Best part about this device is the fact that it can see through infrared light or heat. HST has three sensitive cameras that make it so reliable to take photos in outer space. It can reveal to us what the target is made up of, its color can tell us more about the element and the degree to which how much element is present in it. It can also convey the temperature, density and motion of the object and enable us to sense if the object is moving away or coming closer with the help of this device. Additional features include, seeing visible light, navigating the distribution of dark matter, detecting the universe’s distant objects, search for other planets and most importantly monitor the evolution of galaxies. Recent improvements added to the device enabled us to know the exact diameter and position of stars. The HST undergoes multiple repairs and is upgraded time to time.

This device is seemingly too good to be true but naturally, there are issues. Due to the intensity of the sun’s rays, HST cannot observe the sun. This is why it is always faced away from it. Thus, it means that it can’t observe Mercury, Venus and a few other stars that are closer to the sun.

To think that man could design such an object that would enable us to study these heavenly entities is quite amazing. Curiosity does lead to impressive change and there is a lot more that we need to know about our world still. Given how we are only just beginning to scratch the surface, look at how impressive the results are already! With how technology is progressing, let us hope we can make more inventions to unravel this magnificent wonder that is our universe.

 

by: Nazifa Noor

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