A giant mass of invisible dark matter has managed to give our galaxy this shape, according to a new study published by livescience.com.

Scientists initially believed that the galaxy was a flat disk with two arms that pulled stars from a central barbut measurements taken since the mid-20th century reveal it to be skewed and inexplicably out of shape.

This distortion occurs mainly at the boundaries of our galaxy, where some areas bend down and others up – giving it the appearance of a crushed sombrero, reports livescience.com.

Now, computer simulations reveal why: an invisible halo accounts for the skewed galaxy. The scientists published their findings on September 14 in the journal Nature Astronomy.

“These results, combined with data on the stellar halo, provide strong evidence that our galaxy is embedded in a dark matter halo”the researchers wrote in the study.

Dark matter is a mysterious and somewhat contradictory type of matter. It makes up 85% of the matter in the universe but because it does not interact directly with light, it is completely invisible.

However, scientists can observe its gravitational effects on its surroundings. Dark matter makes its presence known by accelerating stars to otherwise unexplained speeds as they orbit galactic centers. It distorts distant starlight and shapes the galaxy’s halo.

To see what an unbalanced stellar halo might mean for the dark matter halo in which it is suspended, researchers used a computer model to recreate a young Milky Way-like galaxy with a dark matter halo with an inclination of 25 degrees relative to its disk. After simulating the galaxy for over 5 billion years, the researchers found that they had created a galaxy very similar to our own.

Photo credit: ESO