
Molecular oxygen in comet's atmosphere not created on its surface - dnetesn
https://phys.org/news/2018-07-molecular-oxygen-comet-atmosphere-surface.html
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rikkipitt
Fascinating! Last Friday I was closing some curtains on a full (ish) bright
moon, my other half asked what the star beside it was. I told her it was
Jupiter. She then asked what the very dim star beside Jupiter was... I didn't
know so I opened the "Star Walk" iOS app to find out. It was 67P/Churyumov-
Gerasimenko! We couldn't believe we could see it with the naked eye in a major
city. Quite surreal to think that something mankind made is sitting on it...

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dotancohen
Whatever star you saw, it was not the comet. You would have an easier time
squinting and seeing the streptococcus on your teeth in the mirror than you
would see the comet. The bacteria are both larger (angular diameter) and
higher contrast against the background.

You saw another star, in the same general direction of the comet. But it's
cool knowing in what direction that comet is, with our little robot on it.

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baxtr
I really like the educative style of the article. It explains things assuming
almost no level of pre-knowledge. I’d wish more scientific articles were
written like this.

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sitkack
The author also has a podcast,
[http://www.imperial.ac.uk/people/h.dunning](http://www.imperial.ac.uk/people/h.dunning)

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ianai
I could swear Asimov (or someone else) hypothetized that finding oxygen in a
planets atmosphere would indicate the presence of life. Oxygen reacts so
readily with other things that there would have to be a “someone” producing
it. Guess he was wrong. I wonder what would suggest life if found in an
atmosphere.

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whatshisface
> _The new analysis is consistent with team 's original conclusion, that
> molecular oxygen is most likely primordial._

This does not prove that theory wrong. On the surface of an earthlike planet
there would be plenty of reactive material to turn in to oxides. On the
surface of the comet, that wouldn't necessarily be the case.

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ianai
Really good point. Comets wouldn’t typically have volcanic activity, enough
gravity to generate an atmosphere, nor much energy from the sun.

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DoctorOetker
Has the spectrumm of individuaal shooting stars been measured? Do we know
their distribution of compositions?

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drjesusphd
First of all, a shooting star is a meteor, not a comet. So we can do better,
we can recover individual meteorites themselves.

A comet looks stationary in the sky when you see one, only moving noticeably
day by day, like a fast planet.

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DoctorOetker
I knew a comet is not a meteorite, I just had the question lingering around in
my head and was waiting for a tangentially related topic to pop up on HN, in
the hopes that someone who knows would answer if or if not ever the spectrum
of a shooting star aerobraking had been measured.

I ask because the composition of what remains lumped together, and the actual
physical finds of remains may not be representative of the bulk mass
originally entering the atmosphere.

So has distribution of optical spectra of shooting stars been measured? (this
seems hard to me because one would need accurate tracking before it enters in
order to aim the telescope+spectrometer in the right direction for the short
duration it passes the atmosphere)

The reason I ask is because I have an idea on how to try detecting very faint
objects, which may nevertheless be dangerous as rare impacts, or valuable if
it turns out the material would be valuable in bulk before it evaporates in
the atmosphere..

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sidcool
Didn't know comets have atmosphere.

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manicdee
aka Coma

