Astronomers Don’t Cry Over Spilled Milk…They Name Galaxies After It

Milky Way candy bars were created in 1923 by Frank C. Mars, and named after a milkshake of  the time, which was named after our galaxy. The Greeks were the ones who originally named our galaxy “galaxias kyklos,” (which means “milky circle,”) because of the appearance of the part of our galaxy which is visible from Earth at night, which they described as a milky patch of sky.

We know that the candy bar was invented in the 20s and manufactured in Minneapolis, Minnesota. But what about the creation of the galaxy?

Astronomers believe that, roughly 16 billion years ago, the Milky Way galaxy started out as a large, cold sphere of gas rotating in space. The cloud eventually began to collapse in on itself, flattening into a disk as stars began to develop from the gas. Eventually the production of these stars lead to the production of planets and other celestial bodies, and thus the Milky Way was formed. (Source: x)

The shape of the Milky Way is described a “spiral galaxy,” characterized by spiral arms twisting outward from a center bulge. Spiral galaxies are often larger compared to other galaxies, with lots of dust providing a breeding ground for active star formation. Most active star formation takes place in the spiral arms, while older stars are more concentrated near the nucleus of the galaxy. This nuclear bulge is comprised of star clusters, nebulas, and gas, and is located near the Sagittarius constellation.

spiral galaxy

Note that this is NOT a photograph of the Milky Way. We have never been able to leave our galaxy and take a photograph from the outside, but this photograph is not unlike what we speculate the galaxy looks like. (More on that later.)

The photograph above is an example of what the Milky Way might look like from a top-down view. Our sun is about 26,000 light years away from the center of our galaxy, located in a spiral arm named the Orion arm. (That’s about halfway between the nucleus and the edge of the galaxy.) The diameter of the galaxy is much larger than its width, measuring at about 150 thousand light years across.

From the side, our galaxy probably looks like a flattened disk, something like this:

side view spiral glaxy

The thickness of the disk varies at different parts, ranging anywhere between about 400-3000 light years across near the bulge (which, again, is nothing compared to its 150,000 LY diameter.) The amount of dust present in our galaxy obstructs our view of other stars, solar systems, and our view of the galaxy as a whole, making it difficult to study. Because of the dust, radio waves are good for viewing other celestial bodies and especially for studying the galactic bulge, which is relatively bright and massive due to the amount of energy it emits.

As mentioned before, scientists are unable to step outside of our galaxy to study it, which makes it quite difficult to study. Our professor made a comparison to illustrate just how difficult this is, saying that studying the entire Milky Way while being limited to Earth is like studying all of Will County without being able to leave JJC’s main campus. This really helped to put things into perspective. How much could you POSSIBLY learn about Will County from Joliet alone, let alone being limited to our campus?!

As always, astronomers have found a way to study the unknown with what they do know. One way that they are able to estimate the size of our galaxy is by measuring the distance between us and nearby globular clusters, which are groups of lots of older stars found throughout the halo surrounding our galaxy. There are also ways of measuring the mass through equations involving our planet’s/solar system’s orbit around the center bulge, and the orbit of other celestial bodies around it as well.

In order to determine the shape, scientists measure the amount of hydrogen gas in the disk, paying attention to where and how it’s distributed and at what concentration. The presence of hydrogen in enough concentration implies that there are stars, gases, etc, present in those spots. The absence of hydrogen implies the absence of any of these things. Therefore, by pointing their telescope in various directions and mapping out where this hydrogen falls in space, they are able to get an idea of what our galaxy looks likes. From this method, they have found that stars tend to group in arms spiraling outward from the center of our galaxy, and thus we have the widely-accepted belief that the Milky Way is indeed a spiral galaxy.

One final way that scientists study our galaxy from within is by studying other, similar galaxies. Through much research, scientists speculate that our galaxy looks similar to another known galaxy we called M83, pictured below.

m83

Recently, the ALMA telescope was used to capture a photograph of two young galaxies about 12 billion light years away that seem similar to what our own would have looked like in its beginning stages. Apparently, younger galaxies like these can be difficult to study, because our view can be obstructed by the intense light of surrounding quasars. These galaxies were apparently discovered when studying the light coming from these quasars, according to an article on their discovery posted on the ALMA Observatory’s website.

The article, titled “Milky Way-like Galaxies in Early Universe Embedded in ‘Super Halos,'” explains that these galaxies are surrounded by an enormous halo of gas, extending far beyond the disk of the galaxy. Apparently, this gas has an abundance of neutral hydrogen, and there is no new star formation happening there. Both of these galaxies are forming stars at high rates, with one at about 25 solar masses per year and the other closer to 100 per year. The scientists speculate that the material in these massive halos will be used in future star formation.

This article connects to what we learned about the Milky Way because they are similar enough to our own to help us understand our own. The article also mentioned that these galaxies are already rotating, which is indicative of their likely formation into a large spiral galaxy not unlike our own. It has been mentioned in class several times throughout the semester that looking out into space is looking into the past because of how long the light takes to reach us. In the article, the researchers stated that the way we’re seeing these galaxies now is what they were like when our universe was only 8% of its current age. That’s an inconceivably long time ago that these galaxies formed. Although we won’t see it in our own lifetimes, it’s possible that astronomers far into the future will be able to trace the formation of these galaxies as they progress. Once they are older, we could more readily compare their similarities and differences to our own galaxy, and if they are similar enough, this would reveal a great deal of information about the formation of our own, especially since these galaxies are so young and at such an early stage of development.

REFLECTION: I thought this was a great article to include in this conceptual objective because the discovery is so recent and both galaxies are so young. The presence of the massive halos surrounding both of them makes me wonder if we also had such a halo around our galaxy back in the day, or if that is just a unique feature to those specific galaxies. Learning about these galaxies helps us learn about our own, but also about galaxy formation in general, which is an important part of understanding the rest of the universe.

One thing I did not like about the article is the image of the galaxies included at the top, which I was going to include in this post until I realized it was simply an artist’s rendering of what the galaxies may look like. I’m really not interested in someone else’s artistic interpretation of scientific discoveries like this; I much rather would have either the actual image of the galaxies or no image at all.

I also noticed that many, many, many different websites essentially copy and pasted the entire article from its original source and reposted it without giving the original source any credit more often than not. That’s upsetting but I suppose that plagiarism occurs in every professional and educational realm, unfortunately.

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