So for this conceptual objective I’m required to describe the structure and size of our galaxy, The Milky Way, and then I’ll relate the article linked above with the topic and activities/discussions in class.
The Milky Way galaxy is known as a spiral galaxy. This is the typical shape that people think of when you hear the word “galaxy”, a starry swirl in space with a bright center, and (usually) individual arms contained in the shape of a disk. The arms of the galaxy usually create new stars on the outer parts while older stars reside near the center. The Milky Way has four arms: Perseus, Sagitarius, Centaurus, and Outer. Making observations and cataloging the galaxy from within is quite a difficult task. A comparison was made in class; it went, “Imagine being tasked with cataloging every inch, building, animal, person etc. in Will County without being able to leave the campus of JJC”. This comparison makes so much sense because earth is located roughly 26,000 light years away from the core of our galaxy, and it is estimated that the entire galaxy is 150,000 light years across and roughly 2,000 light years in depth. The mass in entirety is approximate mass of the galaxy is one trillion solar masses (1 Solar mass = 1.989 x 10^30 kg) with the core weighing in at 2.6 million solar mass. Scientists haven’t been able to directly observe the center of our galaxy due to a tremendous amount of dust and debris blocking the view. Yet, with infrared and x-ray telescopes, astronomers were able to view stars orbiting a object in such a way and at such speeds (as we discussed in class when, unfortunately the gif wouldn’t work) that it is very likely there is a supermassive black hole at the center.
Image is of galaxies NGC 4302 (left) and NGC 4298 (right) in visible and infrared light. Credits: NASA, ESA, and Mutchler (STScl)
Since it would take thousands of years for a satellite to even exit our galaxy, let alone get far enough to capture a full image, astronomers actually do not know what our galaxy looks like. But, because of the observations and data collected over the years, scientists are able to guess what it looks like, thus the image above. Scientists are able to view other spiral galaxies that are similar in size and shape of our own. NGC 4298 has less prominent spirals than is expected of the Milky Way and NGC 4302 has a lot of dust obscurities along with a large blue area of major star creation. Both galaxies are considerably smaller than the Milky Way. 4298 is 1/3 the size of the Milky Way and 4302 is roughly 60% the size. 4298 is also only 2% the mass at 17 billion SM, while 4302 is 10% the mass of our galaxy at 110 billion solar masses. Overall, the images are simply to give an idea of what our solar system would look like even though the galaxies shown are much smaller and less massive.
I really enjoyed reading this article because it gives the reader an idea of what our galaxy looks like, but still leaves you wanting more because it’s not what our galaxy actually looks like. Also, I feel like it was a nifty way to celebrate The Hubble Space Telescopes 27th birthday. It has been providing us with amazing, high-definition photos for almost three decades and to celebrate it’s birthday it answers a question that a lot of people have been wondering, “what DOES our galaxy look like”. Both entertaining and informative with all the information that the article gives about the galaxies that they were viewing.