Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: Nicolas Salem on 05/04/2011 07:30:02

Title: Are mass extinctions linked to Earth's galactic location?
Post by: Nicolas Salem on 05/04/2011 07:30:02

Nicolas Salem  asked the Naked Scientists:
   
Hi, guys. Great show! Here is my question.

Stars move in and out of density waves as they orbit the galaxy.  

Our sun completes a revolution around the center of our galaxy every ~250 M years as it also presumably moves above and below the plane of the galaxy.  

Mass extinctions, or at least the few we can observe through archeological records, appear to occur more or less at regular intervals.  

Could there be a link between mass extinctions and the passage of the sun in high-density arms of the milky way or through the plane of the
galaxy?

If yes, would mass extinctions be necessarily due to large impacts or could they simply be due to increased radiation? And if yes, when the next one occur?

Thanks,

Nick
Ohio, USA

What do you think?

Title: Are mass extinctions linked to Earth's galactic location?
Post by: JMLCarter on 05/04/2011 23:01:02

Yes, it's a possibility.

http://en.wikipedia.org/wiki/Shiva_hypothesis

Not really well supported by current evidence, even statistically, though.

The sun's heliosphere outshines galactic radiation.

Title: Are mass extinctions linked to Earth's galactic location?
Post by: yor_on on 06/04/2011 03:40:26

No I say :)

Unless you like SF, even more than I do.
Because then everything is possible.
And the cosmic sky is your limit.

Title: Are mass extinctions linked to Earth's galactic location?
Post by: JMLCarter on 06/04/2011 18:25:33

Feel free to add some kind of rationale.

I am really pleased that Matt Smith is getting another season, (guilty as charged).

Title: Are mass extinctions linked to Earth's galactic location?
Post by: yor_on on 06/04/2011 22:28:45

:)

Ah well, I can't disprove it really. But it reminds me of 2012 and?
I have a hard time thinking it could be. I could probably look up starmaps for the extinctions we have but we don't have the exact dates, do we:)

In a similar vein I can also decide that mans extinction will become when we meet the anti-matter floating around, just outside our perception. I mean, why not?

Title: Are mass extinctions linked to Earth's galactic location?
Post by: JMLCarter on 06/04/2011 22:35:54

Personally I think we more or less have the technology to deflect bodies on a collision course with Earth.
A near earth object (NEO) catalog is being established; needs to be a bit more thorough.

Whatever the cause I don't think we are talking about our doom on this one anymore... just a high profile international space mission.

Title: Are mass extinctions linked to Earth's galactic location?
Post by: myself on 08/04/2011 02:05:09

"Mass extinction" is not a precise category.  I'm not sure if the first known one (oxygen atmosphere) is dated precisely enough to correlate, but the others probably are.  You would have to list the mass extinctions and the dates you think they occurred in order to determine whether there is a correlation with galactic orbit.  There is no known mechanism for such a link.  Perhaps a supernova could cause one though.  The next one will probably be global warming though, and we already know the mechanism isn't cosmological.