More Collisions with Comets
There are so many ways that dangers can fall from the skies. Impact by asteroids and comets, radiations from the Sun, stars exploding nearby, gamma rays burst, cosmic rays attack…
As if all these were not enough…
A recent study by scientists at the Cardiff Centre for Astrobiology found that as our Solar System revolves around the Galactic centre, it does not stay “obediently” in the plane of our Milky Way; it keeps “bouncing” up and down through the plane every 35 to 40 million years.
So what does this has to do with dangers from the skies?
As the Solar System pass through the densest part of the galactic plane, due to gravitational interaction with surrounding gas and dust clouds, it can disturb the orbit of comets and might send them flying our way, towards the Earth, increasing our chances of collisions with comet 10-fold!
And our present position in the galaxy suggests we are now very close to another such period!
Evidence of increase collisions in this time period can be seen on the ground. Craters on Earth suggest that we suffer more collisions approximately 36 million years. The comet that believes to wipe out the dinosaurs 65 million years ago also match the periods of comet bombardment.
When the Solar System is at its “maximum” bounce towards the galactic north, it’s about 100 light years above the plane. This is not a good place to be because of the weakening magnetic fields of our galaxy, in which the magnetic fields are important in protecting us from cosmic rays from outer space. These radiations are bad; they can damage our ozone layer or induce genetic mutations.
On the brighter side, the scientists suggest that impact may have thrown debris containing micro-organisms out into space, helping life to spread across the universe.
This is not totally bad news, at least for the micro-organisms.
My Dark Sky 