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Not Your Average Galaxy

March 3, 2014

I recently had the opportunity to attend a lecture by Dr. Patrick Treuthardt, assistant director of the Astronomy & Astrophysics Research Laboratory in the Nature Research Center. This was part of a lecture series that the Museum offers its volunteers so they can learn about research and have a direct opportunity to interact with our scientists on staff. I soon found out that Dr. Treuthardt is a self-identified galaxy geek. He begins the lecture by projecting a beautiful color-infused image of a galaxy far, far away. It is so stellar and radiant, that I am thinking there is no way that something like that exists. Yeah, I have seen pictures of galaxies, but they all blend together like watercolor paintings of oceans. He explains further that we (on Earth) are part of the Milky Way. This is the part of the lecture where I start to salivate, like a Pavlovian dog thinking about chocolate; which is where my mind tends to wander, but then he shows an image of the Milky Way and explains nonchalantly… a galaxy is a massive, gravitationally bound system consisting of stars, stellar remnants, an interstellar medium of gas and dust, and dark matter. I am speechless – of all the things to be what an amazing thing to be. A galaxy sounds so alluring and dark and brooding, like an Ernest Hemingway hero. I always thought that a galaxy is just a galaxy and they are all the same, but I was so very wrong. They are these diverse specters of the universe that we know something and nothing about at the same time.

My simplified summary:

  • Earth is located in the Milky Way galaxy.
  • The Milky Way is made of billions of stars, and not just the twinkly kind.
  • Because of Earth’s location we can only see a certain part of the galaxy, and the rest can only be imagined.
  • You need a recipe of stars, dark matter, dust, and gravity for galaxies to form.
  • Dark matter is dark for a reason.
  • Black holes really do exist, and no, they are not the giant vacuums of the universe.

When all of the main ingredients are combined, galaxies are formed in the universe, and there are a lot of galaxies.

With the help of the Hubble Ultra Deep Field (HUDF) scientists were able to observe these galaxies. Hubble observed a tiny patch of sky (one-tenth the diameter of the moon) for one million seconds (11.6 days) and found approximately 10,000 galaxies, of all sizes, shapes, and colors.

Hubble Ultra Deep Field. Credit: NASA, ESA, R. Windhorst (Arizona State University), and H. Yan (Spitzer Science Center, Caltech).

NASA, ESA, R. Windhorst (Arizona State University), and H. Yan (Spitzer Science Center, Caltech).

In that tiny patch of sky there are thousands of galaxies, and to better understand them, scientists are studying their similarities and differences, beginning with their shapes. Like snowflakes, not all galaxies are the same and like most scientists, astronomers classify them. Galaxies come in all shapes and sizes: from flat spinning discs (pinwheel shaped) to almost-stationary blob-like elliptical galaxies (hoagie shaped).

Most scientist use the Hubble’s Classification Scheme, which separates most galaxies into

  • Elliptical.
  • Normal spiral.
  • Barred spiral.
  • And the galaxies that do not fit into any of these categories are classified irregular (but they don’t know that).
A selection of galaxy images showing the diversity of shapes. (Courtesy: Jamie Symonds/NASA)

A selection of galaxy images showing the diversity of shapes. (Courtesy: Jamie Symonds/NASA)

What makes Dr. Treuthardt’s research a bit more difficult is that, unlike live organisms that you can grow or be collected to study, galaxies can’t be caught or grown or cloned. They are these radiant forms located in a universe so dense that they can barely be seen by the human eye. Astronomers rely on telescopes, like the Hubble Space Telescope to give them an accurate image, and of course, lots and lots of math. Luckily, we have supercomputers that can allow astronomers to simulate what they think galaxies might look like, and how they might move and grow.

Of course, this is a bit oversimplified, because there are components to this research that I cannot even begin to wrap my brain around.  When the lecture was finished I had a new appreciation for galaxies, a strong urge to eat chocolate, and was left completely baffled by dark matter, a whole other crazy space oddity.

But one message was very clear: by studying galaxies we can get a better understanding of the galaxy in which the Earth is nestled. If I was going to live in a house, I would want to know about the materials it was made from, the land it was built on, how that land may change over time and so on. Like most science, researchers can only infer based on observations, but as technology and space exploration progresses scientists can gather data about galaxies and learn more about how they are formed, morph, and even die. One thing is for sure, I will never think of galaxies the same way again.

Want to see Dr. Treuthardt live? Check out our schedule for Meet the Scientist in the SECU Daily Planet Theater.

For more information about galaxies, here are some “out of this world” websites:

  • Hubble Site — See the universe through a new lens.
  • Nasa Galaxies — Get the nitty-gritty on galaxy science.
  • Cosmic Collections — Glimpse the outer universe like never before.
  • Galaxy Zoo — Try your hand at classifying galaxies in this citizen science project.

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