Celestia Forums

can't remember the source but i remember reading 15 yrs ago+/- that our solar system will pass through a giant dust cloud in 50,000 years or so...is this true? If so what impact on life on earth?

As I understand it, this will compress the termination shock and heliosphere and such, allowing more energetic particles from outside to get in. I don't know how accurate that is though.

ELE?

I don?€™t know about a giant gas cloud, but as the Sun orbit the Milky Way, (It takes the Solar System about 225?€“250 million years to complete one orbit of the galaxy) the Sun will move in and out of the spiral arms. As the Sun goes through the arms, all the stars will tend to bunch up, becoming slightly closer, and as they leave it they will speed up again and spread out. The best analogy I have heard is it is like a freeway (highway, autobahn, etc?€¦) at some point, usually around a cure, traffic slows down and the cars bunch together, then after the cure the traffic increase speed and spreads out.

I would hardly worry out this. Instead I would worry more about the oscillation (moving up and down) of the Sun though the galactic plane. Which occurs much more frequently about ever 26 million years. The new theory is that it is this oscillation the causes the majority of the ELE?€™s by disturbing the ort cloud and sending comets into the inner solar system. Interestingly enough it looks like every 225-275 million years there is a Massive ELE that takes place. My guess is that this is caused when the Sun passes through a spiral arm.

http://www.nature.com/nature/journal/v3 ... 712a0.html

Instead I would worry more about the oscillation (moving up and down) of the Sun though the galactic plane.

It's my understanding that we're approaching this cross-point. Yes?

according to this
http://www.nature.com/nature/journal/v3 ... 706a0.html

We passed it about 3 million years ago. Now before someone starts worrying that we are over due for an ELE, I assume there is a lag between when we pass though the galactic plane and the event happens. Unless our race is amazingly stupid, within a hundred years or sooner we will have the ability to detect and alter any rouge asteroid or comets.