TOP 6 MIND BLOWING FACTS ABOUT OUR MILKY WAY GALAXY

The Milky Way Galaxy is an immense and exciting place. Not only does it measure some 120,000–180,000 light-years in diameter, but it is also home to planet Earth, the birthplace of humanity. Our Solar System resides roughly 27,000 light-years away from the Galactic Center, on the inner edge of one of the spiral-shaped concentrations of gas and dust particles called the Orion Arm.

But within these facts about the Milky Way lie some additional tidbits of information, all of which are sure to impress and inspire. Here are ten such facts, listed in no particular order:

1. It’s Warped:

For starters, the Milky Way is a disk about 120,000 light-years across with a central bulge diameter of 12,000 light-years (see the Guide to Space article for more information). The disk is far from perfectly flat, though, as can be seen in the picture below. In fact, it is warped in shape, a fact which astronomers attribute to our galaxy’s two neighbors -the Large and Small Magellanic Clouds.

These two dwarf galaxies — which are part of our “Local Group” of galaxies and maybe orbiting the Milky Way — are believed to have been pulling on the dark matter in our galaxy like in a game of galactic tug-of-war. The tugging creates a sort of oscillating frequency that pulls on the galaxy’s hydrogen gas, of which the Milky Way has lots of (for more information, check out How the Milky Way got its Warp).

2. It Has a Halo, but You Can’t Directly See It:

Scientists believe that 90% of our galaxy’s mass consists of dark matter, which gives it a mysterious halo. That means that all of the “luminous matter” – i.e., that which we can see with the naked eye or a telescope – makes up less than 10% of the mass of the Milky Way. Its halo is not the conventional glowing sort we tend to think of when picturing angels or observing comets.

In this case, the halo is actually invisible. Still, its existence has been demonstrated by running simulations of how the Milky Way would appear without this invisible mass and how fast the stars inside our galaxy’s disk orbit the center.

The heavier the galaxy, the faster they should be orbiting. Assuming that the galaxy is made up only of matter that we can see, then the rotation rate would be significantly less than what we observe. Hence, the rest of that mass must be composed of an elusive, invisible mass – aka. “dark matter” – or matter that only interacts gravitationally with “normal matter.”

To see some images of the probable distribution and density of dark matter in our galaxy, check out The Via Lactea Project.

3. It has Over 200 Billion Stars:

As galaxies go, the Milky Way is a middleweight. The largest galaxy we know of, designated IC 1101, has over 100 trillion stars, and other large galaxies can have as many as a trillion. Dwarf galaxies such as the aforementioned Large Magellanic Cloud have about 10 billion stars. The Milky Way has between 100-400 billion stars, but when you look up into the night sky, the most you can see from anyone point on the globe is about 2,500. However, tHowever, this number is not fixed because the Milky Way is constantly losing stars through supernovae and producing new ones all the time (about seven per year).

4. It’s Really Dusty and Gassy:

Though it may not look like it to the casual observer, the Milky Way is full of dust and gas. This matter makes up a whopping 10-15% of the luminous/visible matter in our galaxy, with the remainder being the stars. Our galaxy is roughly 100,000 light-years across, and we can only see about 6,000 light-years into the disk in the visible spectrum. Still, when light pollution is not significant, the dusty ring of the Milky Way can be discerned in the night sky.

The thickness of the dust deflects visible light (as is explained here),. Still, infrared light can pass through the dust, which makes infrared telescopes like the Spitzer Space Telescope precious tools in mapping and studying the galaxy. Spitzer can peer through the dust to give us apparent views of what is going on at the heart of the galaxy and in star-forming regions.

5. It was Made From Other Galaxies: