12281Our Solar-System's Orbit Through Milky Way's Dark Matter Disk --Does It Trigger
- May 3, 2014URL to an interesting post in the Daily Galaxy blogJohn Brunner used this idea in his great book The Crucible of Time.Chris
Did you ever stop to think, and forget to start again?"
An increased likelihood of life-threatening comet impacts could occur when the Sun passes through a possible dark matter disk in the Galaxy. Our Solar System orbits around the Milky Way’s center, completing a revolution every 250 million years or so. Along this path, it oscillates up and down, crossing the galactic plane about every 32 million years. If a dark matter disk were concentrated along the galactic plane, as shown here, it might tidally disrupt the motion of comets in the Oort cloud at the outer edge of our Solar System. This could explain possible periodic fluctuations in the rate of impacts on Earth.Scientists have uncovered possible evidence of this galactic bumpiness in an apparent periodic fluctuation in the rate of large crater-forming impacts—the kind that likely killed off the dinosaurs. The frequency of impact fluctuations closely matches the rate at which the Sun passes through the plane of the galactic disk. However, it hasn’t been clear what element in the disk could be influencing comet trajectories. Two theoretical physicists have put forward a hypothesis that inserts dark matter as the missing piece between Solar System motion and possibly life-threatening comet impacts. In a paper published in Physical Review Letters, Lisa Randall and Matthew Reece from Harvard University suggest that some of the mysterious invisible matter, which makes up 85% of all matter in the Universe, could exist in a thin disk that disturbs the path of certain comets so that they are more likely to collide with our planet. "