Asteroid crash would devastate ozone layer

Asteroid crash would devastate ozone layer
Deadly rise in UV radiation expected after mid-sized impact
http://physicsworld.com/cws/m/1877/1...cle/news/43996

On Oct 15, 5:07*am, Sam Wormley wrote:
Asteroid crash would devastate ozone layer
Deadly rise in UV radiation expected after mid-sized impacthttp://physicsworld.com/cws/m/1877/17632/article/news/43996

I wonder how the Earth fares in potential collisions in comparison
with other Goldilocks planets. Jupiter is supposed to have mopped up a
lot of debris but the asteroid belt still exists. As do vast numbers
of erratics. In "untidier" solar systems one could imagine the
potential for life being heavily damped.

Chris.B wrote:
On Oct 15, 5:07 am, Sam Wormley wrote:
Asteroid crash would devastate ozone layer
Deadly rise in UV radiation expected after mid-sized impacthttp://physicsworld.com/cws/m/1877/17632/article/news/43996

I wonder how the Earth fares in potential collisions in comparison
with other Goldilocks planets. Jupiter is supposed to have mopped up a
lot of debris but the asteroid belt still exists. As do vast numbers
of erratics. In "untidier" solar systems one could imagine the
potential for life being heavily damped.

Jupiter is a bit ambiguous.

On the one hand it sweeps a lot of garbage, but on the other hand
it disturbs the orbits of a lot of asteroids.
Which then might end up visiting(hitting?) Earth.

On Oct 15, 6:00*am, "Androcles"
wrote:
wrote in message

Entire
species have been wiped out many times as the fossil record
shows.

No, a species can only go extinct once.

Yes, but more than one species has gone extinct on Earth. In fact, the
fossil record shows several major extinction events, which is what I
think the quoted sentence was attempting to say.

John Savard

"Quadibloc" wrote in message
...
No, a species can only go extinct once.

Is that so, Savard? I'd never have guessed. How did you come to
that profound conclusion? Or did W.S. Nelly come up with it?

On Oct 15, 10:31*am, Chris L Peterson wrote:
On Fri, 15 Oct 2010 11:38:07 +0100, "Androcles"

wrote:
No planet is a Goldilocks without a moon, life evolved at the
tidal shoreline where sunlight penetrates shallow water.

That is, at best, an interesting theory regarding the conditions under
which life developed (or a particular line of life) on Earth. To say
that no planet can have the necessary conditions for life to develop
without a moon is carrying the theory much farther than it was intended.
And we don't even know that this is where life developed on Earth. It
seemed reasonable once, but now that we know how much biomass is present
deep in the Earth, and around deep-sea vents, the coastal development
idea seems less likely, or at least, less necessary.

Even without a moon to stabilize the orbit of some hypothetical planet
and cause tides in its ocean, it might still be possible for primitive
"Androcles-like" organisms to develop there. Given enough time even
an Oriel or a Davoud might eventually appear in the planet's fossil
record.

On Oct 16, 5:39*am, wrote:

I'm not going to Androcles any slack.



OK then.


TBerk