(TU) Our Galaxy - The Milky Way Lesson

Our Galaxy - The Milk Way

Each of us are fellow citizens. We are members of one galaxy, the Milky Way.

Our solar system is located in the Milky Way Galaxy. Like other galaxies, the Milky Way contains single stars, double stars, star systems, and lots of gases mixed with dust between the stars. The "milky" or hazy look of our galaxy is due to the light from other stars in our galaxy. Stars are relatively close together, too close for your eyes to distinguish them one from another. The dark patches are clouds of dust that are blocking the path of light from coming from the stars behind those clouds.

The photo on this page clearly illustrates the way humans can get a clear view of parts of the Milky Way. Since Earth is located about two thirds of the way out, in one of the spiral arms within the Milky Way, our galaxy appears to be a narrow disk. We are not able to see the center of our galaxy. However, our galaxy is really a spiral structure that would only be visible if we could move above the entire galaxy.

American astronomer Edwin Hubble made a huge impact on astronomy, and science in general by demonstrating that other galaxies besides our own Milky Way existed. It was the previous belief of many that space was limited to the Milky Way galaxy. Hubble's discoveries
which were announced in 1925 changed our view of the universe. He was also famous for his contribution to the Hubble Telescope.

Structure of Galaxies

There are different structures of galaxies or classifications of galaxies. The Milky Way is a spiral galaxy. Spiral galaxies have a pinwheel shape and are held together by gravity. Some spiral galaxies have arms that are wound tightly, while other galaxies have very loosely-wound arms. These galaxies have a bulge, a thin disk and a halo. Young and old stars are found in a spiral galaxy. Tightly and loosely wound spirals is another characteristic difference between the galaxies, and can be used to classify spirals.

Elliptical Galaxies look like flattened balls and are held together by gravity. Elliptical galaxies contain billions of stars but have very little gas and dust. The galaxies are not great environments for new stars to form and most of the stars found within them are old stars. Elliptical galaxies do not have the spiral arms found in a spiral galaxy and they resemble an ellipse or stretched out circle with a bulge and a disc.

 

Irregular Galaxies are galaxies that simply do not have a regular shape Irregular galaxies may or may not have a nuclear bulge and they do not have any trace of spiral arm structure. They are thought to have probably once been a spiral galaxy or elliptical galaxy but may have unstable gravity that has led to the deformations, but gravity still holds the galaxy together. Irregular galaxies often have an abundance of gas and dust but not always.

Based on what you have read and any research you may conduct, complete the graphic organizer below

 

Let's Put Some Pieces Together

Time for some critical thinking. Scientist use their critical thinking skills to reason and problem solve. Here is the problem. The Universe is so large we can not see all of it or measure it precisely. We can apply our knowledge and basic concepts to develop an initial hypothesis. Don't forget, a hypothesis must be logical, based on observations and prior knowledge, and be testable. Testing our hypothesis may be achieved by using a scientific model or some other type of measurement.

Piece #1 natural phenomenon occurs within systems.

Piece #2 our most commonly accepted theory for the formation of the Universe is the Big Bang Theory which is an explosion of energy outward.

Piece #3 gravity helps us understand objects are attracted to each other.

Piece #4 thanks to Galileo and Newton we understand inertia so we know an object in motion will continue to move in a straight path unless a force is placed upon it.

Piece #5 Hubble observed that object farther apart move faster than objects that are close together.

Piece #6 You have your own observations from the Big Bang Balloon Lab.

One More Thing - This Will Blow Your Mind

Just looking, with no telescope or other instrument for assistance, the Andromeda Galaxy is the most distant object you can see. When you see the Andromeda Galaxy, the light from that galaxy has traveled for 2 million years before it reaches your eyes. So, you are actually seeing what the galaxy looked like 2 million years in the past.

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