The freezing point of carbon dioxide is -78.5C, while the coldest recorded air temperature on Earth has been as low as -92C, does this mean that it can/would snow carbon dioxide at these temperatures?

Saturday, August 18, 2018

The freezing point of carbon dioxide is -78.5C, while the coldest recorded air temperature on Earth has been as low as -92C, does this mean that it can/would snow carbon dioxide at these temperatures?

The freezing point of carbon dioxide is -78.5C, while the coldest recorded air temperature on Earth has been as low as -92C, does this mean that it can/would snow carbon dioxide at these temperatures?
How close could a machine get to the Sun?
How does nuclear fusion produce energy?
How are the atomic masses of the elements measured precisely?
What exactly is spin in quantum mechanics?
How long before 2003 did scientist in the field know about element 115?
Why is it so hard to predict earthquakes?
Do Earth Like Planets Have Vegetation?

Posted: 18 Aug 2018 05:03 AM PDT

For context, the lowest temperature ever recorded on earth was apparently -133.6F (-92C) by satellite in Antarctica. The lowest confirmed air temperature on the ground was -129F (-89C). Wiki link to sources.

So it seems that it's already possible for air temperatures to fall below the freezing point of carbon dioxide, so in these cases, would atmospheric CO2 have been freezing and snowing down at these times?

Thanks for any input!

submitted by /u/FloatingArk54
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How close could a machine get to the Sun?

Posted: 17 Aug 2018 08:31 AM PDT

I was reading about the Parker probe and it's amazing just how close that thing is going to get to the sun; but it of course made me wonder how much closer we could get. The Parker probe basically uses a big oriented shield to protect itself, and behind the shield it's more a normal spacecraft.

Is it conceivable that anything could be constructed that could survive passing through the corona? It seems stuff must be whipping around like crazy in there, plus the insane temperatures. To my knowledge the highest known melting points are in the thousands of degrees, but I figure there is also some kind of blast force or something going on there.

Edit and if the corona is so easy, can you conceive of a spacecraft passing through the photosphere and surviving?

Not that it is possible with any known technology, but is it even physically conceivable that something could survive a close approach towards the surface of the sun? What would be necessary (special materials? some kind of super-magnet?)?

edit 2 Thanks all for the entertaining and informative comments! I will let you all know when my machine is completed and ready for launch.

submitted by /u/aggasalk
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How does nuclear fusion produce energy?

Posted: 18 Aug 2018 03:12 AM PDT

From where does energy where two hydrogen atoms produce one helium atom come from?

How much mass is actually lost in the process?

Giving that helium atom is almost as four times heavier than hydrogen atom how is this even possible?

submitted by /u/Let_me_tug_it
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How are the atomic masses of the elements measured precisely?

Posted: 17 Aug 2018 02:08 PM PDT

I am an ib physics student and I was recently going through an unit on energy production. One of the topics was about fission reactions, in which a question involved the isotopic mass of Uranium-235 (and its reaction in reactors). I noticed that the mass was given all the way out to 6 significant figures. I looked up a reference table and it is reported out to 10 digits with a relative uncertainty of 8.5x10^-7% (!!). In the same table, I also see elements like Oxygen-16 (13 digits) or Sodium (12 digits). This is extremely precise. I was wondering what the process behind the measurement was and what sorts of instruments are used?

Also, as a follow up question. When and why are such precise measurements needed? Are there practical differences between this and slightly less precise measurements or are they just because we can? I assume its related to particle physics/quantum mechanics.

submitted by /u/backman_10
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What exactly is spin in quantum mechanics?

Posted: 17 Aug 2018 06:24 AM PDT

None of the explanations get traction in my head.

submitted by /u/GoodMerlinpeen
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How long before 2003 did scientist in the field know about element 115?

Posted: 17 Aug 2018 03:10 PM PDT

I'd love some information on this because I can only basically find the 2003 peer review for Moscovium

submitted by /u/LifebehindbarsHD
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Why is it so hard to predict earthquakes?

Posted: 17 Aug 2018 01:38 PM PDT

Always seemed weird to me how little progress we have made in predictions.