[HN Gopher] Lunar samples returned by Chang'e-5 tell of recent v...
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       Lunar samples returned by Chang'e-5 tell of recent volcanism
        
       Author : rbanffy
       Score  : 29 points
       Date   : 2021-10-08 14:52 UTC (2 days ago)
        
 (HTM) web link (arstechnica.com)
 (TXT) w3m dump (arstechnica.com)
        
       | TheDesolate0 wrote:
       | Clickbait title.
       | 
       | 2 Billion years ago.
       | 
       | Not recent by any stretch of the imagination.
        
         | amelius wrote:
         | In astronomy words related to time and distance have a
         | different meaning than in everyday use.
        
           | spfzero wrote:
           | I still don't think anyone would think 2.5 billion years ago
           | would be recent, on a body that is only 4.5 billion years
           | old. 2.5 billion in the past is less than mid-point in the
           | moon's age, closer to the beginning than the end.
        
         | lanerobertlane wrote:
         | As the strapline says, recent is relative in astronomical
         | terms.
         | 
         | For example the margin either side of it being 2 billion is 59
         | million years either way...
        
           | jcelerier wrote:
           | What would be ancient then ? Because if 2B is recent, 4.5B
           | can't be ancient, yet the moon potentially didn't even exist
           | ?
        
             | anonnyj wrote:
             | In the infiniteness of time, 2 billion is a blink if the
             | eye.
        
               | edgyquant wrote:
               | But not relative to the age of the moon it isn't, which
               | is what's being discussed.
        
             | lanerobertlane wrote:
             | I'm not sure there's a consensus, I expect it depends on
             | your astronomical area of study. If you study the whole
             | universe, than our solar system at 4.5B years old is pretty
             | recent compared to the 14B years of the universe, so
             | there's no ancient history of the moon.
             | 
             | I'd say if you studied the moon, anything that happened in
             | it's early lifetime is ancient so the protomoon and first
             | billion years into it's existence, maybe.
             | 
             | I guess it's similar to how people studying evolution class
             | Humans as a recent event, but people who study humans class
             | the the Pyramids as ancient history.
        
               | mr_toad wrote:
               | That's still a seventh of the age of the universe. It'd
               | be like a historian referring to the US war of
               | independence as recent history.
        
         | [deleted]
        
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       (page generated 2021-10-10 23:01 UTC)