[ExI] oxygen on 67p

BillK pharos at gmail.com
Thu Oct 29 08:44:37 UTC 2015

On 29 October 2015 at 05:02, Dan TheBookMan  wrote:
> On Wed, Oct 28, 2015 at 6:59 PM, spike wrote:
>> Never mind that!  Nature is reporting that there is oxygen on comet 67P!
>> Please, how in the heeeeeelllll could there be oxygen on a comet?
>> How weird is this!  Everything I thought I understood about comet
>> formation is either suspect or outright wrong.
> One way to save the failing theory is just to pretend it all has to with
> there being so many comets. Vast numbers! Astronomical numbers! Therefore,
> one of them is bound to really odd. (Well, another way is simply not to have
> a well worked out and cherished theory about comet formation. That's my
> method.:)

Science News has some thoughts....

Oxygen’s presence supports the long-held assumption that comets are
pristine fragments from the dawn of the solar system. Comet 67P must
have been put together gently, Bieler says, otherwise the ice-coated
grains that make up its bulk would have been heated and the oxygen
removed. Because the grains have not been heated, they are unprocessed
time capsules — frozen samples that preserve the conditions that
prevailed when the planets were forming.

Ultraviolet light from the sun and free-range electrons are probably
responsible for creating the O2 in the first place. High-energy
photons and particles can zap water molecules, which in turn reform
into molecules of oxygen (and hydrogen). The oxygen was then trapped
within ice that collected on dust grains, which in turn came together
to assemble the comet. There the oxygen stayed protected for nearly
the age of the solar system. As recently as 1840, comet 67P was far
enough out in the solar system to escape the sun’s destructive
influence, but an encounter with Jupiter nudged it in closer. With
each close approach to the sun, heat reaches into the comet,
sublimates the ice, and liberates the O2.

If oxygen is tucked away in similar grains found in star-forming
clouds, oxygen might be more abundant than thought. “The picture of
interstellar chemistry is not as simple as some people would make it,”
he says.


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