Two More Arms in Our Galaxy (but does it have eyes in the back of its head?)
What has a disc, four arms, spurs and is full of gas? Our Milky Way galaxy, of course. Well, we thought it had only TWO arms until recently.
Since 2008, scientists believed our Milky Way galaxy, the one in which our solar system resides in the universe, had two arms. But after observing images from NASA’s Spitzer Space Telescope, they now have a better idea of what our galaxy looks like.
A galaxy is made up of millions of stars and the systems that orbit those stars. Our sun is one of those stars. In fact, scientists have charted the stars in our galaxy and have determined that we are located near a small, partial arm called the Orion Arm, or Orion Spur, located between the Sagittarius and Perseus arms. You can see our location in the galaxy image above.
The millions of stars in the Milky Way galaxy form a central, densely populated disc. There are also two thick arms filled with stars and gases, spiraling out from the disc, along with two smaller arms.
Why didn’t we see those two smaller arms sooner? Well, it is a little difficult to observe our galaxy, looking from the inside out, but thanks to our perfect location on a smaller arm, and using super telescopes like the Spitzer scope, we ARE able to see what is located around us pretty well. Scientists can figure out our galaxy’s shape based on other stars’ locations and their distances from us.
Yet, if our sun was located inside one of the major arms or in the central disc, we would not be able to see beyond the thousands of surrounding stars. We would be unaware of not only our own galaxy but the other thousands and thousands of galaxies in our universe.
Our perfect location gives us this window-seat view of the universe. We are able to behold its vastness and the glorious expanse of Creation!