Unveiling the Mystery: What Exactly Is Dark Matter—and Where Is It Hiding in Our Galaxy?
Hello to all the curious individuals out there! If you have ever found yourself gazing up at the sky at night and wondering about all the invisible stuff that holds your galaxy together, then you are not alone. The topic of this weeks article is one of the universe’s most fascinating enigmas: dark matter. What is it? Where in the Milky Way Galaxy does it reside? Why is it so puzzling for the scientific community?
The Invisible Glue of the Cosmos
First things first – Dark Matter is not dark simply for lack of a substance being black or some type of mystery “black” material, but rather dark, meaning it does not emit, absorb, or reflect light. It is completely invisible and yet comprises roughly 85 percent of the total matter in the universe; that’s a pretty impressive number! The existence of dark matter is necessary for galaxy (including our own) structure to remain intact. If the mass attributed to dark matter were missing, stars would be thrown out of orbit and the structures we see in the cosmos would be much different than what we see today.
How do scientists know that dark matter exists? Scientists are able to find evidence of dark matter based on how galaxies rotate and how light bends around large objects due to an effect known as gravitational lensing. The basic idea behind this is there appears to be “more” mass in galaxies than what can be seen, however this excess mass can be measured through its gravitational effects.
Where Is Dark Matter in Our Galaxy?
Picture the Milky Way Galaxy as a massive, spinning pinwheel. All that you can see is only the brighter areas of the pinwheel (the arms) and the center (the core). Dark Matter? It’s believed to be a large spherical shell of material around the galaxy with boundaries extending way past the edge of what you can see of the galaxy. This shell of material acts as a gravitational scaffolding to keep all the stars orbiting within the galaxy at their correct distances from each other, especially out toward the edges of the galaxy where regular matter becomes very thin.
The evidence for the existence of dark matter has been known for many years; however, despite numerous attempts over the last several decades by researchers using large experiments underground and on satellites in space, no one has yet detected any evidence for the existence of dark matter.
Why Does This Matter to Us?
You may be wondering why unpeeling the layers of the cosmos can be worthwhile for the challenge. If we were able to understand dark matter, it would completely redefine physics and open up new technology possibilities. It also brings into focus that there are still many mysteries of the universe left to explore and to create a sense of awe and curiosity about what lies ahead.
If this sparks an interest in you, I suggest you look at the variety of documentary films (such as “The Dark Universe”) and podcasts which include astrophysicist talks from experts such as Dr. Katie Mack. These help make the science come alive without overwhelming you with technical jargon.
Looking Ahead
Next week I am going to explore another fascinating question about whether there is life elsewhere in our universe. Before I get to that question, though, let’s spend some time contemplating just how much we still do not know – and what a wonderful source of enchantment is the mystery of the unknown in our vast universe. Thanks for accompanying me on this intergalactic journey. Keep looking up and keeping the wonder alive until next time!