Size and Structure of the Milky Way Galaxy

The fifteenth conceptual objective, “I can describe the structure and size of the Milky Way Galaxy”, has been a topic of discussion in class as of late. Determining the size and shape of the Milky Way Galaxy is difficult because we live inside of it. In order to get a better idea of what it looks like, one must view it from outside and essentially “take a step back”. Other galaxies give astronomers a better understanding of what ours might look like, by making comparisons. The Milky Way Galaxy is classified as a spiral galaxy. A thin disk surrounding the center of the galaxy contains over 100 billion stars and is about 100,000 light-years in diameter. Our Sun is located about 28,000 light-years from the center of the galaxy. In class, we exercised this concept in the Lecture-Tutorial book. In the section titled, “Milky Way Scales”, in the Lecture-Tutorial book, we were asked to investigate the distances and sizes of objects within the galaxy and outside the galaxy elsewhere in the universe which gave us a better understanding of the size of the Milky Way Galaxy. This tutorial has given me a better understanding of the true size and structure of the Milky Way Galaxy.

The article I chose, “Old Stardust in Young Galaxy Sheds Light on the First Stars”, focuses on a galaxy that is located nearly 13 billion light-years away from Earth. The galaxy is named A2744_YD4, and was viewed with the process of gravitational lensing. The galaxy is so far away that astronomers see it how it looked when the universe was only 600 million years old. Astronomers used a spectrograph instrument to analyze the light coming from stars to determine its size and composition. Unlike studying the Milky Way Galaxy, A2744_YD4 is far enough away to determine its characteristics. It is difficult to know exactly what the Milky Way looks like due to the fact that we are in it. This article relates to the fifteenth conceptual objective because it discusses how scientists observe the size and structure of other galaxies. Describing the structure and size of a galaxy must be done with extensive observations.

This article compares to the fifteenth conceptual objective because it determines the size and structure of a galaxy. In order to make observations about our own galaxy, astronomers must make comparisons to other galaxies. A2744_YD4 gives astronomers insight on what our galaxy might look like and what our universe was like in the past. This article clearly demonstrates our fifteenth conceptual objective by determining certain characteristics about galaxies, such as size and structure. This article was very interesting to me, as it allowed me to get a better understanding of how galaxies are studied and compared to the Milky Way Galaxy.


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