A gigantic blob of invisible dark matter has bent our galaxy out of shape, a new study suggests.

Scientists initially believed that the Milky Way was a flat disk dominated by two spiral arms trailing stars from a central bar, but measurements taken since the mid-20th century reveal that it’s bent inexplicably out of shape.

The warping occurs mostly at our galaxy’s borders, where some regions bend downward while others flare upward — giving it the look of a crushed sombrero. Now, computer simulations may have revealed the cause: a mysterious event that knocked our galaxy’s invisible halo of dark matter out of alignment. The scientists published their findings Sept. 14 in the journal Nature Astronomy.

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“These results, in combination with data in the stellar halo, provide compelling evidence that our Galaxy is embedded in a tilted 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 universe’s matter; but because it doesn’t directly interact 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 inexplicable speeds as they orbit galactic centers; warping distant starlight; and by giving shape to the Milky Way’s galactic halo.

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