Science Forums 2

[Turtle]

Originally Posted by Eclogite

However in a letter to Nature (Periodic mass extinctions and the Sun's oscillation about the galactic plane) these astronomers note the periodicity to be 26 million years.
In another letter to Nature (The Sun's motion perpendicular to the galactic plane) we are told "For all the models we consider, the most recent passage of the Sun through the galactic plane occurred in the past 3 Myr provided only that the present position of the Sun is between 0 and 20 pc above the plane."

Please note that the full cycle is double whatever of the above figures we go with.

Great info Eclogite! I could only read the Abstracts, but it's enough to get the sense no one has as precise a measure of our location as some have suggested. To whit, the guy I heard talking that prompted this thread was claiming our solar system was going to cross the galactic plane in 2012.

So we only know our perpindicular position to within 20 pc (parsecs, right?) and our distance from the center of the galaxy within 10,000 light-years, so anyone claiming knowledge of a precise time of our crossing is exagerating the facts...yes?

But still, even the Nature blurb seems to allow enough error that we could still be approaching the glactic plane. The game's still afoot then, if for no other reason than no one seems to have said if we are now above, or below the galactic plane. Then there's that haunting nasty business of extinction, and while the Nature articles have it correlated to the galactic plane, the article I got the 33 million year cycle from correlated extictions to our position in relation to the Local Bubble.

Originally Posted by americanscientist

...The sun is on the edge of what is sometimes called the Local Bubble, a great void in the distribution of interstellar gas in the nearby galactic neighborhood.

American Scientist Online - The Galactic Environment of the Sun

Plane it may be, simple it is not.